Histories of Maize: Multidisciplinary Approaches to the Prehistory, Linguistics, Biogeography, Domestication, and Evolution of Maize [1 ed.] 0123693640, 9780123693648

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Histories of Maize

The Italian explorer Girolamo Benzoni (c. 1541–55) recorded the steps involved in processing husked corn to make fresh dough. First the kernels were ground with a mano and metate and then patted into small cakes and finally cooked on a comal or griddle (from Girolamo Benzoni, La historia del mondo nvovo di M. Girolamo Benzoni Milanese, Venetia, F. Rampazeto. 1565. p. 56, verso). Images such as this woodcut and accounts from various chroniclers who came to the New World emphasized the role of maize as a primary staple, the staff of life, essentially synonymous to Old World wheat and barley. These early descriptions and the later role of maize as one of the world’s primary economic staples predisposed many scholars to emphasize and, in some instances, assert that Zea mays L. was the catalyst to the development of civilization in this hemisphere. The contributions in this volume demonstrate that its role was more complex and varied than had been previously assumed. These histories of maize show that in some cases its symbolic role to ethnic identity, religion, and elite status may have been as important as its economic role to such developmental processes. (Courtesy of the Rare Books Division, The New York Public Library, Astor, Lenox and Tilden Foundations)

Histories of Maize Multidisciplinary Approaches to the Prehistory, Linguistics, Biogeography, Domestication, and Evolution of Maize

Edited by

John E. Staller Department of Anthropology University of Kentucky

Robert H. Tykot Department of Anthropology University of South Florida

Bruce F. Benz Biology Department Texas Wesleyan University

AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEW YORK • OXFORD • PARIS • SAN DIEGO SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Academic Press is an imprint of Elsevier

Academic Press is an imprint of Elsevier 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA 525 B Street, Suite 1900, San Diego, California 92101-4495, USA 84 Theobald’s Road, London WC1X 8RR, UK This book is printed on acid-free paper. Copyright © 2006, Elsevier Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone: (+44) 1865 843830, fax: (+44) 1865 853333, E-mail: [email protected]. You may also complete your request on-line via the Elsevier homepage (http://elsevier.com), by selecting “Support & Contact” then “Copyright and Permission” and then “Obtaining Permissions.” Library of Congress Cataloging-in-Publication Data Histories of maize : multidisciplinary approaches to the prehistory, linguistics, biogeography, domestication, and evolution of maize / edited by John E. Staller, Robert H. Tykot, Bruce F. Benz. p. cm Includes bibliographical references and index. ISBN 0-12-369364-0 (alk. paper) 1. Corn—History. I. Staller, John E. II. Tykot, Robert H. III. Benz, Bruce F. SB191.M2H64 2006 633.1′509—dc22 2006040228 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library ISBN-13: 978-0-12-369364-8 ISBN-10: 0-12-369364-0 For information on all Academic Press publications visit our Web site at www.books.elsevier.com Printed in the United States of America 06 07 08 09 10 9 8 7 6 5

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Working together to grow libraries in developing countries www.elsevier.com | www.bookaid.org | www.sabre.org

In memory of Richard S. MacNeish and Donald W. Lathrap for their inspiration, insights, and pioneering research on the origin and culture history of maize.

Contents

P A R T

3. Origin of Polystichy in Maize

I

HUGH H. ILTIS

Abstract 22 Introduction: The Origin of Maize 23 The Maizoid Eve—An Emphatic Restatement 27

HISTORIES OF MAIZE: GENETIC, MORPHOLOGICAL, AND MICROBOTANICAL EVIDENCE

The Maizoid Eve Concept Is Useful and Should Not Be Rejected 28

First for Sugar, Then for Grain: Reflections on Corn Domestication Chronology 28 The Cupulate Fruitcase and the Ear Cluster: Adaptive Marvels of Coordinated Sequential Maturation 32 The Origin of Polystichy in Maize 33

1. Differing Approaches and Perceptions in the Study of New and Old World Crops TERENCE A. BROWN

An Abbreviated History 33 The “Twisted Cob Hypothesis” of Collins: Its Merits and Follies 34 What Happened After Tga 1 Caused the Maizoid Revolution? 35 Collins’ Figure, With All of Its Faults, Is a Classic Illustration 35 The Origin of Polystichy in Maize: The “Second Bifurcation”—A Reappraisal 38

Introduction 3 Different Emphases in New and Old World Agriculture 4 Reasons for the Difference in Emphasis 4 Outcomes of the Difference in Emphasis 5

Different Perceptions of the Role of Science 6

2. Maize in the Americas

The Shank and Its Husks—The Key to Maize Ear Polystichy 39

BRUCE F. BENZ

Maize Polystichy—With Its Roots in the Shank to Its Glory in the Ear 39 On the Inexcusable Neglect of the Shank and Its Husks 41 A Note on Twisting, and the Basic Bilateral Dorsiventrality of Zea 42 Edgar Anderson and the Shank—The Story of an Unconsummated Love Affair 43 The Condensation in the Maize Shank and Its Husks and Preconceived Notions 44

Purpose and Scope of Review 9 Introduction 10 Genetic Evidence of Teosinte Domestication 11 Genetic Evidence of Population Manipulation 12 Archaeological-Macrobotanical-Evidence of Teosinte Domestication and Maize Agriculture 15 Pollen Evidence for Use of Zea and Climate Change and Phytoliths Document Neotropical Plant Domestication 16

From Teosinte Distichy to Maizoid Polystichy: Or How to Study Husk Phyllotaxy in Nine Easy Steps 45

Juxtaposing the Archaeological and Genetic Evidence for Early Maize 18

Iltis and His Gigantic Footnote 45

S. G. Stephens and the Shank Condensation Theory— Sharp-Eyed, Unsung, Uncited, and Unequivocally Correct 49 Postscript 50

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4. Dating the Initial Spread of Zea mays MICHAEL BLAKE

Introduction 55 Temporal Frameworks for Zea mays’ Early Dispersal 56 Direct Dating of Maize 57 On the Indirect Dating of Maize 59 Dating the Early Distribution of Zea Pollen 60 Dating the Early Distribution of Maize Phytoliths 63 Dating the Early Distribution of Moderate-to-High Stable Carbon Isotope Ratios 65 Comparing the Different Lines of Evidence 68 Discussion of the Social Implications of Maize’s Early Spread: Initial Uses of Maize 68

The Timing and Sequence of Selection for Key Attributes in Maize: Combining Morphological and Molecular Evidence 90 Loss of Natural Seed Dispersal Mechanisms 91 Fewer Larger Seed “Packages” 91 Loss of Germination Dormancy 91 Terminal Seed Clusters and Uniform Ripening 92 Improved Starch and Protein Quality 92 Future Directions in Ancient DNA Analysis of Crop Plants 92

7. Ancient Maize in the American Southwest: What Does It Look Like and What Can It Tell Us? LISA W. HUCKELL

5. El Riego and Early Maize Agricultural Evolution BRUCE F. BENZ, LI CHENG, STEVEN W. LEAVITT, AND CHRIS EASTOE

Introduction 73 Domestication and Agriculture 74 Methods 75 Results: Calibrating and Averaging AMS Dates 77 Results: Morphological Trends and Rates 78 Results: Evolutionary Rates 78 Results: Stable Isotope Determinations 79 Discussion and Summary 80

Introduction 97 Archaeological Context 98 Chronology 98 The Sites 98

Analysis of the Maize: Methods and Materials 99 Results 101 Discussion 104 Conclusions 106

8. Environmental Mosaics, Agricultural Diversity, and the Evolutionary Adoption of Maize in the American Southwest WILLIAM E. DOOLITTLE AND JONATHAN B. MABRY

6. Ancient DNA and the Integration of Archaeological and Genetic Approaches to the Study of Maize Domestication VIVIANE R. JAENICKE-DESPRÉS AND BRUCE D. SMITH

Introduction 83 Morphological and Molecular Approaches to Documenting the Early History of Maize 84 Molecular Level Analysis of Archaeological Maize: A Case Study 85 Monitoring for Selection of Preferred Attributes in Ancient Maize 85 The Archaeological Maize 87 Tb1: Maize Plant Architecture 4400 Years Ago 87 Pbf and Su1: The Development of Starch and Protein Properties 88 Population Substructure in the Sugary-1 Gene 89

Introduction 109 The Simplistic Paradigm 110 Proto-Agriculture 111 Diversity in Early Water Management 112 Agricultural Niches in an Environmental Mosaic 115 Maize Varieties and Crop Complexes 115 Conclusion 117

9. Toward a Biologically Based Method of Phytolith Classification GREG LADEN

Introduction 123 The Raw Data and Its Presumed Meaning 124 Exploring Genetic versus Nongenetic Variation 124 Conclusions 128

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II STABLE ISOTOPE ANALYSIS AND HUMAN DIET 10. Isotope Analyses and the Histories of Maize ROBERT H. TYKOT

Isotope Definitions 131 History of Isotope Studies 132 Sample Preparation and Isotopic Analysis 135 Interpretation and Significance of Carbon and Nitrogen Isotope Data 136 Oxygen and Strontium Isotopes 138 Isotope Studies in This Volume 139

11. Social Directions in the Isotopic Anthropology of Maize in the Maya Region CHRISTINE D. WHITE, FRED J. LONGSTAFFE, AND HENRY P. SCHWARCZ

A Brief History of Isotopic Anthropology in Mesoamerica 143 Ideology 145 Social Structure 145 Rise of Social Differentiation 148 Socioeconomic Status 148

Intraelite Differentiation 150 Gender 150 Trade 153 Identification of the “Other” in Sacrifices 153 Conclusion 155

12. Diet in Prehistoric Soconusco BRIAN CHISHOLM AND MICHAEL BLAKE

Introduction 161 Sample Selection 162 Sample Preparation and Analysis 162 Plant Results 162 Animal Results 163 Human Results 165 Conclusions 167

13. Early to Terminal Classic Maya Diet in the Northern Lowlands of the Yucatán (Mexico) EUGENIA BROWN MANSELL, ROBERT H. TYKOT, DAVID A. FREIDEL, BRUCE H. DAHLIN, AND TRACI ARDREN

Introduction 173 Methods 174 Isotopic Studies of the Maya 174 Yaxuná 174 Chunchucmil 177

Discussion and Conclusion 180

14. The Importance of Maize in the Initial Period and Early Horizon Peru ROBERT H. TYKOT, RICHARD L. BURGER, AND NIKOLAAS J. VAN DER MERWE

Introduction 187 Archaeological Sites Tested 188 Pacopampa 188 The Manchay Culture Sites of the Lurin Valley 189 Mina Perdida 190 Tablada de Lurin 191

Stable Isotope Analysis 191 Results and Discussion 193 Pacopampa 193 Cardal 194 Mina Perdida 194 Tablada de Lurin 195

Conclusion 195

15. Maize on the Frontier: Isotopic and Macrobotanical Data from Central–Western Argentina ADOLFO F. GIL, ROBERT H. TYKOT, GUSTAVO NEME, AND NICOLE R. SHELNUT

Introduction 199 Zea mays on the Frontier: A South American Case 201 The Study Area 201 Domesticates: Maize and Other Resources in the Late Holocene 202 Isotopic Ecology and Human Diet: δ13C and δ15N Information 202 Late Holocene Human Diet and the Use of Maize 207 The Zea mays Frontier Adoption Model 211 Final Remarks 212

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16. Dietary Variation and Prehistoric Maize Farming in the Middle Ohio Valley DIANA M. GREENLEE

Introduction 215 Late Woodland and Late Prehistoric Subsistence Records 217 Theory and Method 217 Theoretical Framework 217 Generating Dietary Data 218

The Isotope Record of Dietary Change 220 Multiple Populations? 221 Recent Efforts to Account for Dietary Change 221

Geographic Variation in Maize-Based Farming Systems 222 Recent Efforts to Account for Geographic Variation in Diet 223 Evaluation 229

Site Background 252 Cross Creek and Melton Mound I (Inland Sites) 252 Crystal River (An Estuary Environment) 252 Dunwoody, Pillsbury, Bay Pines, Horr’s Island, Weeden Island, and Bayshore Homes (Coastal Sites) 253

Processing and Analyzing Skeletal Material 253 Stable Isotope Results for All Sites 254 Cross Creek and Melton Mound I (Inland Sites) 254 Crystal River (Estuarine Site) 256 Bay Pines, Dunwoody, Pillsbury, Bayshore Homes, Weeden Island, Horr’s Island (Coastal Sites) 256

Discussion 257 Inland Sites 257 Crystal River 258 Coastal Sites 258

Conclusion 259

Conclusions 229 Future Directions 231

19. Prehistoric Maize in Southern Ontario: Contributions from Stable Isotope Studies M. ANNE KATZENBERG

17. A Hard Row to Hoe: Changing Maize Use in the American Bottom and Surrounding Areas ELEANORA A. REBER

Introduction 236 Models of Maize Adoption in the American Bottom 236 Types of Analysis Used 237

Introduction 263 Previous Studies 264 Stable Isotope Analysis of Faunal Remains: Earlier Study and New Data 265 Refining Estimates of the Introduction of Maize in Southern Ontario from Human Collagen Samples 270 Conclusions 270

Paleoethnobotany and Stable Carbon Isotope Analysis 237 Pottery Residue Analysis 238

Early Emergent Mississippian 239 Late Emergent Mississippian 241 The Mississippian Lohmann Phase (CAL AD 1050–1100) 242 Middle Mississippian Phases (CAL AD 1100–1350) 243 Stirling Phase (CAL AD 1100–1200) 244 Moorehead Phase (CAL AD 1200–1300) 244

Discussion 244 Conclusions 245

18. Evidence for Early Use of Maize in Peninsular Florida JENNIFER A. KELLY, ROBERT H. TYKOT, AND JERALD T. MILANICH

Introduction 249 The Natural Setting of Peninsular Florida 250 Historic Evidence for Plant Foods in Florida 251 Stable Isotope Studies in Florida 251 Human Skeletal Samples in This Study 252

20. The Stable and Radio-Isotope Chemistry of Eastern Basketmaker and Pueblo Groups in the Four Corners Region of the American Southwest: Implications for Anasazi Diets, Origins, and Abandonments in Southwestern Colorado JOAN BRENNER COLTRAIN, JOEL C. JANETSKI, AND SHAWN W. CARLYLE

Introduction 276 Overview of Basketmaker II Research 276 Site Descriptions 277 Talus Village 277 Sites 22 and 23 277 Site 22 278 Site 23 278 Unnamed Sites 278

Methods 278 Stable Carbon Isotope Analysis 278 Stable Nitrogen Isotope Analysis 278 Laboratory Procedures 278

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Results 279 Discussion 283 Talus Village 284 Sites 22/23 284 Pueblo II–III Burials 285 Radiocarbon Chronology 285

Conclusion 285

21. The Agricultural Productivity of Chaco Canyon and the Source(s) of Pre-Hispanic Maize Found in Pueblo Bonito LARRY BENSON, JOHN STEIN, HOWARD TAYLOR, RICHARD FRIEDMAN, AND THOMAS C. WINDES

Introduction 290 Agricultural Productivity and Population Densities of the Chaco Canyon Core Area 292 Acres under Cultivation 293 Southwestern American Indian Maize Yields and Rates of Consumption 301 Estimated Population Densities Supported by Chaco Canyon Maize Production 301 Areas from Which Maize May Have Been Imported 301

Archaeological Maize Samples 302 Chemical Tracing of Biological and Archaeobiological Materials 302 Methodological Considerations: Sampling and Laboratory Methods 303 Results and Discussion 307

Summary and Conclusions 311

22. Stable Carbon Isotope Analysis and Human Diet: A Synthesis HENRY P. SCHWARCZ

Introduction 315 Theoretical Basis of the Use of Isotopes 316 The Significance of Isotopes in Reconstruction of Paleodiet in the Americas 316 Rate of Spread of Maize and Agriculture 317 Isotopic Studies in North America 318 Mesoamerica 319 South America 319 Other Isotopic Methods 320 Conclusions 320

III HISTORIES OF MAIZE: THE SPREAD OF MAIZE IN CENTRAL AND SOUTH AMERICA 23. Caribbean Maize: First Farmers to Columbus LEE A. NEWSOM

Introduction 325 Caribbean Biogeography and Physical Geography in Brief 326 Synopsis of the History of Human Settlement and Cultivation Practices 327 The Evidence for Maize: Archaeological Research 329 Archaeobotany 329 Human Bone Chemistry 331

Discussion 331 Why Such a Low Signal? 331 The Development of a Uniquely Caribbean Cuisine 332

Conclusion 333

24. Maize on the Move J. SCOTT RAYMOND AND WARREN R. DEBOER

Introduction 337 Ethnographic Evidence 338 Discussion 340 Conclusions 341

25. The Gift of the Variation and Dispersion of Maize: Social and Technological Context in Amerindian Societies RENÉE M. BONZANI AND AUGUSTO OYUELA-CAYCEDO

Introduction 344 The Development of Ceramics: Its Social Setting 345 Ceramics and Maize: Dispersion in South America and the Caribbean 345 Timing of Maturation of Maize 350 Conclusions 351

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26. The Maize Revolution: A View from El Salvador

29. Prehistoric Maize from Northern Chile: An Evaluation of the Evidence

ROBERT A. DULL

MARIO A. RIVERA

Introduction 357 Making Sense of Fossil Zea Pollen from El Salvador and Beyond 358 Prehistoric Maize from Western El Salvador 360 The Pacific Coastal Plain 360 The Rio Paz Basin 360 The Sierra de Apaneca–Llamatepec Highlands 361

Prehistoric Maize Fields from Central El Salvador 362 Valle de las Hamacas (San Salvador) 362 The Zapotitán Basin 363

Conclusions 363

Introduction 403 The Archaeological Evidence 403 Tiliviche 404 Camarones 404 Quiani 406 Cáñamo 407 Caleta Huelén-43 407 Chiu Chiu 407 Guatacondo-Ramaditas 407 Tulan 408 Pichasca, San Pedro Viejo 409 El Salto 409

Discussion of the Evidence 409

27. Pre-Columbian Maize Agriculture in Costa Rica: Pollen and Other Evidence from Lake and Swamp Sediments SALLY P. HORN

Introduction 368 Maize Pollen Identification and Dispersal and Associated Paleoecological Evidence 368 Maize Pollen in Archaeological Regions of Costa Rica 370 The Central Highlands–Atlantic Watershed Archaeological Region 371 The Guanacaste–Nicoya Archaeological Region 375 The Diquís Archaeological Region 376

Conclusion 376

SERGIO J. CHÁVEZ AND ROBERT G. THOMPSON

Introduction 415 Archaeological Background and Paleobotanical Maize Samples from Copacabana 417 Opal Phytoliths 419 Food Residue Phytolith Assemblages 420 Maize Chaff Assemblages 422 Blind Tests of Phytolith Assemblage Recognition 423

Materials and Methods of Phytolith Identification in Ancient and Modern Samples 423

28. Caral–Supe and the North-Central Area of Peru: The History of Maize in the Land Where Civilization Came into Being RUTH SHADY

Introduction 381 The Social System of Caral–Supe 382 The Territory of Caral 383 The Settlement of Caral 385 Tools for Farming 387 Maize from Caral 387 Residential Sector A, Subsector A1 387 Subsector A5 391 Sector I2–Residential Units 391 Sector H1: The Gallery Pyramid 392 Sector C, Subsector C2 393 Residential Sector NN2 395 Settlement of Miraya, Subsector C4 396 Sector C5 398

Interpretations 399 Conclusions 401

30. Early Maize on the Copacabana Peninsula: Implications for the Archaeology of the Lake Titicaca Basin

Comparisons of Residues and Modern Maize Varieties 425

Discussion and Conclusions 426

31. The Movements of Maize into Middle Horizon Tiwanaku, Bolivia CHRISTINE A. HASTORF, WILLIAM T. WHITEHEAD, MARIA C. BRUNO, AND MELANIE WRIGHT

Introduction 429 Tiwanaku: An Early Highland Polity 430 The Andes: Ecological Diversity, Maize Diversity 431 Maize at Tiwanaku 432 Hypotheses 432

Research Goals 433 Data 434 Methods 435 Analysis of the Data 435 Results 437

Discussion 441 Conclusions 443

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32. The Social, Symbolic, and Economic Significance of Zea mays L. in the Late Horizon Period JOHN E. STALLER

Introduction 449 The Social and Symbolic Significance of Maize 451 Social and Symbolic Aspects of Maize to Interaction and Sealing Alliances 454

Maize Consumption 491 Maize Production 492 Maize Trait Variation 494 Conclusions: Trend or Departure? 495

35. Early Maize Agriculture in the Northern Rio Grande Valley, New Mexico BRADLEY J. VIERRA AND RICHARD I. FORD

An Encounter of Historic Proportions 456

The Significance and Role of Maize to Andean Economy 462 Symbolic Aspects of Maize to Inca State Religion 464 Summary and Conclusions 465

Introduction 497 A Review of Early Agriculture in the Northern Rio Grande 498 An Evaluation of Early Maize Morphology and Dates in the Northern Rio Grande 501 Early Agriculture in the Northern Rio Grande 505 Conclusion 507

P A R T

IV HISTORIES OF MAIZE: NORTH AMERICA AND NORTHERN MEXICO 33. Early Agriculture in Chihuahua, Mexico ROBERT J. HARD, A. C. MACWILLIAMS, JOHN R. RONEY, KAREN R. ADAMS, AND WILLIAM L. MERRILL

Introduction 471 Early Agriculture 471 The Introduction of Maize 473 Early Agriculture in Chihuahua 474 Paleoenvironment 474 Previous Research in Chihuahua 475 Northwestern Chihuahua 475 South-Central Chihuahua 478 D-Shaped Terrace Sites 478 Cerros de Trincheras 479

The Sierra Tarahumara 479 Discussion 480

34. Protohistoric and Contact Period Salinas Pueblo Maize: Trend or Departure? KATHARINE D. RAINEY AND KATHERINE A. SPIELMANN

Introduction to the Salinas Area 487 Research Questions and Data 489 Data Sample 490 Data Analysis Techniques 490

36. Hominy Technology and the Emergence of Mississippian Societies THOMAS P. MYERS

Introduction 511 Hominy Technology 511 Alternative Methods of Hominy Production 512 Other Methods of Freeing the Essential Nutrients 514

Testing the Hypothesis 514 A New Race of Maize 514 Cultural Changes 515 Physical Changes 515

Origins of the Hominy Revolution 516 American Bottoms and the Central Mississippi 516 Lower Mississippi and Arkansas Lowlands 516 Southeast 517 Northeast 517

Conclusions 517

37. The Migrations of Maize into the Southeastern United States ROBERT LUSTECK

Introduction 521 Phytoliths 521 The Assemblage Approach 522 Maize History and Varieties 522 Maize in the Southeastern United States 523

The Pilot Study 524 Methods and Materials 524 Results 524

Conclusion 524

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38. The Science behind the Three Sisters Mound System: An Agronomic Assessment of an Indigenous Agricultural System in the Northeast JANE MT. PLEASANT

Introduction 529 Mounds 530 Soil Temperature and Moisture 531 Soil Organic Matter 532 Soil Fertility 532 Soil Erosion and Compaction 532 Spacing and Plant Population 533

Intercropping 534 An Integrated System 535

39. The Origin and Spread of Maize (Zea mays) in New England ELIZABETH S. CHILTON

P A R T

V HISTORIES OF MAIZE: THE LANGUAGE OF MAIZE 41. Siouan Tribal Contacts and Dispersions Evidenced in the Terminology for Maize and Other Cultigens ROBERT L. RANKIN

Introduction 564 Glottochronological Dating 564 Impressionistic Dating 565 Improving Dating Techniques 565 Gourds 566 Squash (Often Pumpkin) 566 Maize 567

Other Technology 571 Beans 571

Introduction 539 The Maize Debate and Mobile Farmers 540 New England’s Mobile Farmers 540

The Maize Chronology and the Importance of AMS Dating 541 Maize Dating Project 543 Implications of a Chronology for Maize Horticulture in New England 545

Summary 572 The Agricultural and Technological Chronology 574 The Siouan Family Tree 574 Further Research 575

42. Maize in Word and Image in Southeastern Mesoamerica BRIAN STROSS

40. Pre-Contact Maize from Ontario, Canada: Context, Chronology, Variation, and Plant Association GARY W. CRAWFORD, DELLA SAUNDERS, AND DAVID G. SMITH

Introduction 549 Middle Woodland, Late Woodland I, and Late Woodland II in Southern Ontario 550 Paleoethnobotany of Middle Woodland, Princess Point, and Late Woodland II 551 Maize in the Northeast 552 Princess Point Maize 554 Contexts 554 Plant Associations 554

Late Woodland I Maize Morphology 556 Discussion 556

Introduction 578 Vocabulary 579 Basic Maize Words 579 Maize Growth Stages 581 Food Preparation 581 Ritual Names and Maize Deities 583

Narratives 583 Sayings, Metaphors, and Beliefs 586 Rituals 586 Numbers 588 Glyphs 589 Images 591 Calendar 593 Plants 596

Conclusion 597

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43. Thipaak and the Origins of Maize in Northern Mesoamerica JANIS B. ALCORN, BARBARA EDMONSON, AND CÁNDIDO HERNÁNDEZ VIDALES

Introduction 600 Thipaak Maize Histories 600 Thipaak and Maize in Conversation and Daily Life 604 Maize Cultivation Rituals 606 Relation to Other Mesoamerican Traditions 606 Discussion and Concluding Observations 608

44. The Place of Maize in Indigenous Mesoamerican Folk Taxonomies NICHOLAS A. HOPKINS

Introduction 612 The Ethnobotany of the Amuzgo 612 Amuzgo Ethnobotany and Folk Taxonomy 613 Comparative Mesoamerican Plant Categorization 616 Tzeltal (Mayan) Ethnobotanical Categories 616 Chuj (Mayan) Ethnobotanical Categories 617 Itzá (Mayan) Ethnobotanical Categories 618 Popolocan (Otomanguean) Ethnobotanical Categories 618

The Emergence of Mesoamerican Life Forms 618 Classic Maya Science 619 Concluding Remarks 620

45. Native Aymara and Quechua Botanical Terminologies of Zea mays in the Lake Titicaca and Cuzco Regions SERGIO J. CHÁVEZ

Introduction 623 Historical Background of Quechua and Aymara Languages 624 Tunqu (Aymara) and Sara (Quechua) Maize Terminologies 625 Maize Plant Parts 625 Maize Varieties 626

Chicha, K’usa (Aymara), and Aqha (Quechua) Terms 627 Conclusions 628

46. The Historical Linguistics of Maize Cultivation in Mesoamerica and North America JANE H. HILL

Introduction 631 Historical–Linguistic Methods 632

Reconstructed Maize Complex Vocabularies in Mesoamerican Languages 633 Maize Complex Loan Words in Mesoamerican Languages 636 Maize Vocabularies in the Southwestern United States 640 Maize Vocabulary in the Eastern United States 642 Summary and Conclusion 643

47. Glottochronology and the Chronology of Maize in the Americas CECIL H. BROWN

Introduction 648 Glottochronology 649 Methodology 650 Theoretical Considerations Concerning Terms for Maize in Ancestral Languages 654 Chronology of Maize in the Americas 655 Maize Chronology and Glottochronological Dates 656 Adjusting Glottochronology 661 Conclusion 662

48. The Antiquity, Biogeography, and Culture History of Maize in the Americas BRUCE F. BENZ AND JOHN E. STALLER

The Culture History of Maize in the Americas 665 Contextual Considerations 665

Antiquity 666 Biogeography: Dispersal and Racial Diversification 667 Culture History—Staple, Variety, and Cultural Acceptance 668 Maize in Language, Legend, and Myth 671 Extinction 672 Index 675 Color Plate follows page 366

Contributors

Karen R. Adams (33) Crow Canyon Archaeological Center, Cortez, Colorado 81321

Li Cheng (5) Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona 85721

Janis B. Alcorn (43) The Garfield Foundation, Chevy Chase, Maryland 20815

Elizabeth S. Chilton (39) Department of Anthropology, University of Massachusetts, Amherst, Massachusetts 01003

Traci Ardren (13) Department of Anthropology, University of Miami, Coral Gables, Florida 33124

Brian Chisholm (12) Department of Anthropology and Sociology, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada

Larry Benson (21) U.S. Geological Survey, Boulder, Colorado 80303

Joan Brenner Coltrain (20) Department of Anthropology, University of Utah, Salt Lake City, Utah 84112

Bruce F. Benz (2, 5, 48) Biology Department, Texas Wesleyan University, Ft. Worth, Texas 76105

Gary W. Crawford (40) Department of Anthropology, University of Toronto at Mississauga, Mississauga, Ontario L5L 1C6, Canada

Michael Blake (4, 12) Department of Anthropology and Sociology, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada

Bruce H. Dahlin (13) Department of Sociology and Anthropology, Howard University, Washington, D.C. 20059

Renée M. Bonzani (25) Department of Anthropology, University of Kentucky, Lexington, Kentucky 40506

Warren R. DeBoer (24) Department of Anthropology, Queens College, City University of New York, Flushing, New York 11367

Cecil H. Brown (47) Department of Anthropology, Northern Illinois University, DeKalb, Illinois 60115

William E. Doolittle (8) Department of Geography and the Environment, University of Texas–Austin, Austin, Texas 78712

Terence A. Brown (1) Faculty of Life Sciences, Jacksons Mill, University of Manchester, Manchester M60 1QD, United Kingdom

Robert A. Dull (26) Department of Geography and the Environment, University of Texas at Austin, Austin, Texas 78712

Maria C. Bruno (31) Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri 63130

Chris Eastoe (5), Department of Geosciences, University of Arizona, Tucson, Arizona 85721

Richard L. Burger (14) Department of Anthropology, Yale University, New Haven, Connecticut 06520

Barbara Edmonson (43) Anthropology Department, Tulane University, New Orleans, Louisiana 70118

Shawn W. Carlyle (20) Department of Anthropology, University of Utah, Salt Lake City, Utah 84112

Richard I. Ford (35), Museum of Anthropology, University of Michigan, Ann Arbor, Michigan 48109

Sergio J. Chávez (30, 45) Department of Anthropology, Central Michigan University, Mt. Pleasant, Michigan 48859

David A. Freidel (13) Department of Anthropology, Southern Methodist University, Dallas, Texas 75275

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Contributors

Richard Friedman (21) City of Farmington Geographic Information Systems, Farmington, New Mexico 87401

A. C. MacWilliams (33) Department of Archaeology, University of Calgary, Calgary, Alberta T2N 1N4, Canada

Adolfo F. Gil (15) Departamento de Antropología, Museo de Historia Natural de San Rafael, (5600) San Rafael, Mendoza, Argentina

Eugenia Brown Mansell (13) Department of Anthropology, University of South Florida, Tampa, Florida 33620

Diana M. Greenlee (16) Department of Anthropology, University of Washington, Seattle, Washington 98195 Robert J. Hard (33) Department of Anthropology, University of Texas at San Antonio, San Antonio, Texas 78249 Christine A. Hastorf (31) Department of Anthropology, University of California, Berkeley, California 94720 Jane H. Hill (46) Department of Anthropology, University of Arizona, Tucson, Arizona 85721 Nicholas A. Hopkins (44) Department of Modern Languages and Linguistics, Florida State University, Tallahassee, Florida 32306 Sally P. Horn (27) Department of Geography, The University of Tennessee, Knoxville, Tennessee 37996 Lisa W. Huckell (7) Maxwell Museum of Anthropology and Department of Anthropology, University of New Mexico, Albuquerque, New Mexico 87131 Hugh H. Iltis (3) Department of Botany, University of Wisconsin–Madison, Madison, Wisconsin 53706

William L. Merrill (33) Department of Anthropology, Smithsonian Institution, Washington, D.C. 20002 Jerald T. Milanich (18) Florida Museum of Natural History, Gainesville, Florida 32601 Jane Mt. Pleasant (38) Horticulture Department, Cornell University, Ithaca, New York 14853 Thomas P. Myers (36) University of Nebraska State Museum, Lincoln, Nebraska 68588 Gustavo Neme (15) Departamento de Antropología, Museo de Historia Natural de San Rafael, (5600) San Rafael, Mendoza, Argentina Lee A. Newsom (23) Department of Anthropology, The Pennsylvania State University, University Park, Pennsylvania 16802 Augusto Oyuela-Caycedo (25) Department of Anthropology, University of Florida, Gainesville, Florida 32611 Katharine D. Rainey (34) Archaeobotanical Consultant, Huntersville, North Carolina 28078 Robert L. Rankin (41) Department of Linguistics, University of Kansas, Lawrence, Kansas 66044

Viviane R. Jaenicke-Després (6) Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig D-04103, Germany

J. Scott Raymond (24) Department of Archaeology, University of Calgary, Calgary, Alberta T2N 1N4, Canada

Joel C. Janetski (20) Department of Anthropology, Brigham Young University, Provo, Utah 84602

Eleanora A. Reber (17) Department of Anthropology, University of North Carolina at Wilmington, Wilmington, North Carolina 28401

M. Anne Katzenberg (19) Department of Archaeology, University of Calgary, Calgary, Alberta T2N 1N4, Canada Jennifer A. Kelly (18) Department of Anthropology, University of South Florida, Tampa, Florida 33620 Greg Laden (9) Department of Anthropology, University of Minnesota, Minneapolis, Minnesota 55455

Mario A. Rivera (29) Beloit College, Beloit, Wisconsin, Cotsen Institute of Archaeology, University of California, Los Angeles, California 90095 John R. Roney (33) Albuquerque Field Office, Bureau of Land Management, Albuquerque, New Mexico 87107

Steven W. Leavitt (5) Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona 85721

Della Saunders (40) Department of Anthropology, University of Toronto at Mississauga, Mississauga, Ontario L5L 1C6, Canada

Fred J. Longstaffe (11) Department of Earth Sciences, The University of Western Ontario, London, Ontario N6A 5C2, Canada

Henry P. Schwarcz (11, 22), School of Geography and Earth Sciences, McMaster University, Hamilton, Ontario L8S 4M4, Canada

Robert Lusteck (37) Department of Anthropology, University of Minnesota, Minneapolis, Minnesota 55455

Ruth Shady (28) Caral-Supe Special Archaeological Project, Lima, Peru

Jonathan B. Mabry (8) Desert Archaeology, Inc., Tucson, Arizona 85716

Nicole R. Shelnut (15) Department of Anthropology, University of South Florida, Tampa, Florida 33620

Contributors

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Bruce D. Smith (6) Archaeobiology Program, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20013

Robert H. Tykot (10, 13, 14, 15, 18) Department of Anthropology, University of South Florida, Tampa, Florida 33620

David G. Smith (40) Department of Anthropology, University of Toronto at Mississauga, Mississauga, Ontario L5L 1C6, Canada

Nikolaas J. van der Merwe (14) Archaeology Department, University of Cape Town, South Africa, Rondebosch 7701, South Africa

Katherine A. Spielmann (34) Department of Anthropology, Arizona State University, Tempe, Arizona 85287

Cándido Hernández Vidales (43) Tamjajnec, S. L. P., Mexico

John E. Staller (32, 48) Department of Anthropology, University of Kentucky, Lexington, Kentucky 40506 John Stein (21) Navajo Nation Historic Preservation Department, Chaco Protection Sites Program, Window Rock, Arizona 86515 Brian Stross (42) Department of Anthropology, The University of Texas, Austin, Texas 78712 Howard Taylor (21) U.S. Geological Survey, Boulder, Colorado 80303 Robert G. Thompson (30) Interdisciplinary Archaeological Science, University of Minnesota, Minneapolis, Minnesota 55455

Bradley J. Vierra (35) Los Alamos National Laboratory, Ecology Group M887, Los Alamos, New Mexico 87545 Christine D. White (11) Department of Anthropology, The University of Western Ontario, London, Ontario N6A 5C2, Canada William T. Whitehead (31) Department of Anthropology and Sociology, Ripon College, Ripon, Wisconsin 54971 Thomas C. Windes (21) National Park Service, Albuquerque, New Mexico 87106 Melanie Wright (31) UK Data Archive, University of Essex, Colchester, Essex CO4 3SQ, United Kingdom

An Introduction to the Histories of Maize JOHN E. STALLER Department of Anthropology, University of Kentucky, Lexington, Kentucky1

The goal of the editors of this volume on maize is to bring together contributions, which would individually incorporate and collectively assemble a comprehensive multidisciplinary set of data, that developed particular lines or types of evidence from specific time periods (and regions) throughout the Pre-Columbian geographic range of maize cultivation.2 Another primary goal in organizing this volume was to be holistic, in that the total range of coverage would encompass the entire Western hemisphere and include research from the social, biological, and earth sciences. This volume is organized into five parts dealing with different aspects and regions of research on the origin and spread of maize science. The scope and breadth of the research takes into account recent methodological and technological innovations from the physical, biological, and social sciences. These recently developed technical and methodological approaches provide ever-increasing detail and direct evidence on the antiquity, evolution, and cultural importance of maize in the ancient Americas. We believe that such approaches have essentially transformed our understanding of the roles and importance of maize and other domesticates to sociocultural developments in prehistory, making this publication timely. My colleagues, Robert H. Tykot and Bruce F. Benz, and I hope that the readers of this volume agree that the research presented herein has established this to be the case. One of our two European contributors observed that such a book could never have been realized had it been organized and published outside of North America (see Chapter 1). Rather it would have been broken up into several books specialized on the respective scientific discipline and spe-

cialization concerned. These volumes would have presumably included research that was specifically geared to the interested specialists in those fields. Archaeological research on the domestication of grains in the Old World has developed within competing models that consider “acculturation” or “waves of advance,” whereas in the Americas they have generally been couched within foraging–farming dichotomies that are specific and distinct to different regions of the hemisphere and their associated time periods [4, 5, 6, 9, 19]. Although the Old World approaches lend themselves well to models used or tested by human geneticists and linguists, they have generally been anathema to North American archaeologists. In the Old World, emphasis has been placed on initial causes or events (as opposed to earliest presence), whereas here in the Americas there has been a clear focus on the developmental processes or evolutionary processes, or both, associated with plant domestication and maize agriculture. The Old World emphasis on migration and diffusion of plant domestication also takes away from the general focus on the distinctions that important cultigens had to different regions and time periods, whereas in the Americas this has been clearly evident in the methodological approaches to understanding the archaeological record (see Chapters 23 and 36). Despite differences in theoretical and methodological approaches to plant domestication in general and economic plants (mainly grains) in particular, the assumption that maize, like wheat and barley in the Old World, provided the economic basis for the development of civilization has been a central thesis among scholars in the archaeological sciences in both hemispheres. Remarkably, many of the contributions in this volume challenge those basic assumptions. Although the chapters in this volume appear to support the contention that maize was a major economic staple, some contributions herein indicate that when and where this occurred is dramatically different than had been previously suggested in the literature. Other contributors present evidence to suggest that the way maize affected sociocultural processes is in fact far more complex and varied than had

1

Research Associate, Department of Anthropology, The Field Museum, Chicago, Illinois 2 The creation of this volume on the Histories of Maize was inspired in part through collaboration with several colleagues, T. Michael Blake, John P. Hart, and Robert G. Thompson, in putting together a four-part symposium on maize titled Stories of Maize for American archaeology that was presented at the 69th Annual Meeting of the Society for American Anthropology in Montreal, Canada, March 31–April 4, 2004.

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been originally assumed (see Chapters 8 and 21). One of the primary themes that runs through many of these contributions, particularly the paleodietary evidence from stable carbon isotopes, is that maize was not initially the important economic food source that many archaeologists assumed (see Chapters 2, 3, 5, 6, 11–13, 20, and 28). In some cases, it never achieved economic importance in certain regions, although it did seem to play an important role in other aspects of sociocultural development (see Chapters 24, 25, and 30). Another important divergence from previous assumptions brought out by this volume is that maize was only domesticated once. Its ancestor, teosinte (Zea mays ssp. parviglumis), was domesticated in the Balsas River drainage of central Mexico (see Chapters 2 and 3) [14]. This differs from previous hypotheses regarding a tripartite origin of maize promoted by Mangelsdorf [13] and others and by extension the possibility of multiple domestication events in different regions of the Americas [8, 11, 15, 17]. Since the publication of the DNA microsatellite data on extant populations of maize and teosinte in 2002, research on ancient maize has been at a historical crossroads [14]. These important data suggest that, like most of the Old World staples, maize was only domesticated once, but rather than focus on the migrations of farming populations or the acceptance of maize agriculture in diverse regions, what the contributions in this volume suggest is that there will be an even greater appreciation for research on maize from the social and particularly the biological sciences. The botanical evidence has historically influenced archaeological interpretation, but the recent evidence from molecular biology suggests that such data may now set the limits for what is possible regarding the ancient origins and early spread of maize in the Americas [7]. The holistic approach we have inherited from the founders of American Anthropology is largely responsible for the multidisciplinary organization of this volume [12, 16, 21–24]. They provided Americanist archaeology with the possibility that such multidisciplinary approaches could ever have been brought together as a single reference source on maize science. Many recent advances to our knowledge come from new scientific techniques and approaches to the direct study of archaeological maize collections and the physical remains of the human populations who consumed it (see Chapters 29 and 31). The development of Accelerator Mass Spectrometry (AMS) radiocarbon dating has had a profound effect on our understanding of the chronological spread of maize in the Americas and greatly revised our previous assumptions of its antiquity based on indirect dating techniques [2, 3, 18, 20]. The recent techniques involving isotope analysis, including research on phytoliths, have provided detailed information on the antiquity and role of maize to ancient cultures throughout the Americas and are highlighted and referenced throughout the volume (see Chapters 9, 17, 30,

and 37). These state-of-the-art scientific approaches and their associated methodologies stand in contrast to the more traditional forms of analyses such as historical linguistics, archaeological analysis of stratigraphy, and the classification and detailed study of artifacts. The first section of this volume deals with the molecular, biological, and morphological research that has so greatly affected recent research on maize. This section of the volume also includes a detailed analysis of the chronology of its spread in the Americas (see Chapter 4). Recently developed techniques in maize DNA research have also revised our earlier perceptions of the antiquity and spread of maize to different regions of the Americas and provided evidence for the previously unknown presence of undomesticated teosinte genes (see Chapter 6). Chapter 2 by Benz, on maize in the Americas, addresses some of these biological and chronological data and the underlying biases in previous research methodologies when maize was still believed to have multiple origins [13]. Several chapters present data derived from the latest advances in the study of maize origins—morphology and microfossil analysis—asking the question: What can such research on ancient maize tell us about the origin, history, and spread of this important cultigen? Chapters presenting evidence on the physical characteristics of archaeological maize remains also include an assessment of methodological approaches on microfossils in carbon residues that appear to provide greater detailed information on the identification and spread of ancient maize lineages (see Chapters 7, 9, 26, 27, 34, and 37). These chapters suggest that the future of maize research will be more heavily influenced by molecular biology, particularly the maize genome project, and botanical research on plant morphology, as scholars will attempt to quantify, identify, and trace those genes, traits, and morphological characteristics related to human as opposed to natural selection. An economic staple throughout the Western hemisphere at the time of European contact, the evolution and spread of maize (Zea mays L.) have been topics of major archaeological research in the Americas for more than a century [1]. The second part of the volume deals with stable carbon isotope analysis and paleodiet and directly addresses these previous concerns with direct quantitative evidence of its economic importance. Researchers working in areas ranging from as far afield as southern Canada and Argentina discuss the dietary, social, and economic implications of stable carbon isotope analyses from human skeletal remains (see Chapters 15 and 40). Research using strontium isotopes and elemental analyses of biochemistry involving human skeletons, as well as plants and animals, can now be used to determine whether people, plants, or animals were displaced or brought in from other areas or regions than where they were identified archaeologically. Strontium isotopic research is generating data that have facilitated our understanding of how maize was manipulated and used by ancient

An Introduction to the Histories of Maize

societies and challenges our previous assumptions of how maize was dispersed and its role in the ancient economy (see Chapter 21). In recent years, multidisciplinary research using a variety of new methods and techniques in stable carbon isotope analysis has clarified and provided detailed data on the dietary importance of maize in distinct cultural settings and time periods (see Chapter 10). Isotopic research on ancient human skeletons, particularly in the past decade, has greatly expanded our understanding of human adaptation and, in some cases, required maize specialists from the natural and social sciences to revise long-held theories on the spread and effects of maize on the development of sociocultural complexity. The section on stable carbon isotope analysis provides the most up-to-date results on paleodiet in the Americas. The summary by Henry Schwarcz (see Chapter 22) represents one of the most comprehensive treatments of these data in the published literature. Results from various contributions indicate that maize became a primary staple in the Americas much later than had been previously thought and that its role in sociocultural development is much more complex and varied in some regions of the Neotropics, particularly in the areas adjacent to where it was originally domesticated (see Chapter 13). In other regions of the Americas it became a food staple late in the prehistoric sequence, and in some regions its adoption and role in the ancient economy was highly varied, and it was never a primary staple (see Chapters 15, 16, 18, and 19). These data provide refreshing and informative insights into the spread and economic importance of maize, and in many ways they challenge our previous assumptions of its importance and role in sociocultural development. The chapters in Parts III and IV are organized chronologically by geographic region, going from the earliest evidence of maize domestication to its later spread into other areas of the hemisphere. Considerations of the scientific, theoretical, and methodological approach also influenced the organization of this volume. The geographic and topical divisions are in two parts: Part III: Central and South America and Part IV: North America and Northern Mexico. Many recent scientific advances in our knowledge surrounding the increasing dependence on plant domestication, and particularly the role of maize in ancient economies, are explored in these chapters. Most of the research is archaeological, and many contributions incorporate the most recent multidisciplinary evidence to build consensus on primary issues surrounding maize science that are based on internally consistent lines of evidence. The innovative and original approaches presented in this volume provide a basis for the future of multidisciplinary research on this important New World cultigen. Part III represents a natural extension of the first parts of the volume in its multidisciplinary research and geographic and chronological breadth and scope and is distinguished to

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some extent in that the research primarily concerns the social sciences—the ethnohistory, archaeology, and contextual associations of ancient maize. Numerous ethnohistoric documents and ethnographic accounts are presented to examine the social and symbolic significance of maize to sociocultural development. Ethnohistoric accounts generally emphasized maize as the preeminent grain of the PreHispanic New World, a plant that was critical to sociocultural developments in Mexico and Central and South America at the time of contact. These accounts were largely biased by the importance of cereal grains in the Old World and have long influenced archaeological assumptions regarding the economic role of maize in Native American economies. In exploring little-known ethnohistoric accounts of Native Andean speakers one of the contributions has uncovered evidence that suggests that maize also played a major role in cultural perceptions of hierarchy and status and that its role in the economy went far beyond dietary considerations (see Chapter 32). Recent multidisciplinary lines of evidence have recorded the changing role of maize to sociocultural development in different chronological, geographic, and cultural settings. The ethnographical, ethnohistorical, paleobotanical, and archaeological evidence presented in these chapters has generated even more detailed evidence of complex sets of data regarding the phylogeny, chronology, evolution, and the sociocultural and socioeconomic significance of this important New World cultigen. The different social and symbolic roles maize played are explored in diverse chronological and cultural settings (see Chapters 31, 34, and 35). Other chapters emphasize the significance of Native American practices regarding maize agriculture. The intercropping of the maize, beans, and squash triad is examined from an agronomic perspective, and the spread of maize lineages is traced through time and space (see Chapters 38–40). Some contributors trace the early movements of maize into the American Southwest and northern Mexico and provide innovative and original insights into its role in sociocultural development and adaptation (see Chapters 33 and 35). The linguistic section of this volume, Part V, takes the reader back into Americanist anthropological science. The chapters presented here are multidimensional in scope and comprehensive in the regions covered. Some contributors use historical linguistics such as glottochronology to explore the dispersal of this plant among the widely dispersed Siouan language family in North America and the multibranched language families (Mayan, Mixe–Zoquean, Oto–Manguean, and Uto–Aztecan) and language groups of Mesoamerica (see Chapters 41 and 46). Cecil Brown (see Chapter 47) uses linguistic analysis to trace the spread of the terminology surrounding maize by various Native linguistic groups throughout the hemisphere. Moreover, the results from this ambitious contribution indicate that such data are largely consistent with the most current chronological evi-

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dence of its spread. These contributions emphasize the importance of historical linguistics and language to our understanding of the antiquity, meaning, and roles of maize in widely dispersed and economically diverse cultures. Some linguistic contributors examined the vocabularies surrounding the cultivation and preparation of maize to correlate them with established archaeological dates for their introduction with linguistic developments, whereas others analyzed indigenous folk taxonomies to explore the meaning and uses of maize among ethnographic cultures and by extension their ancient ancestors (see Chapters 44 and 45). Brian Stross (see Chapter 42) analyzes images of maize, which are depicted in iconography, discussed in narratives, and stylized in glyphs, to gain an understanding of the ideological and mythological significance that this plant had to Mayan civilization. Alcorn, Edmonson, and Hernández Vidales (see Chapter 43) explore the mythological origins and cultural significance of maize as it is expressed in language and revealed in legend and song of the Teenek (Huastec) of San Luis Potosi and Veracruz, who are currently residing in the moist tropical forests and dry forest zones on the eastern side of the Sierra Madre Oriental. In prehistoric times they also lived along the Gulf Coast, up through Tamaulipas, and into the dry areas west of the mountains—including the area of the cave where teosinte and small maize ears were discovered by Richard MacNeish decades ago. The ethnographic and linguistic evidence presented in this part of the volume represents an affirmation of American anthropological science, and as Gordon Willey and Philip Phillips [23] once said, “archaeology is anthropology or it is nothing at all” [p. 2]. The linguistic chapters are in this part of the volume to emphasize the anthropological roots of American archaeology and reaffirm what was stated at the beginning of this introduction. It has been only a decade since the last important landmark synthesis on maize science was published, but as these chapters clearly indicate, much has changed and been redefined regarding the spread and significance of maize in that short period of time [10]. In the volume summary, Benz and Staller (see Chapter 48) explore the multidisciplinary research on maize in different regions of the Americas to show how the data presented in this volume are in some cases a natural extension of the previous results and in other ways a dramatic departure with conclusions and data that directly challenge the conventional wisdom and provide compelling evidence to suggest that many of our current assumptions and preconceptions are no longer tenable. This final statement on the volume and maize science reaffirms the power of integrating multiple lines of internally consistent data in light of the previous claims and assumptions that have been made in the important and often controversial history of research on maize.

Acknowledgments I would like to express my sincerest thanks to Irwin Rovner (North Carolina State University) and Bruce F. Benz (Texas Wesleyan University) for their readings of preliminary drafts of this introduction to the volume. Their comments and suggestions provided valuable insights. I take all responsibility for the contents, assessments, and opinions expressed in this introduction. I would also like to extend my sincerest thanks to The Field Museum, particularly the research library. Most of the research, planning, and organization of this volume and the symposium from which it was derived was undertaken while I was a research associate with the museum, and if it was not for the assistance of the library staff and my access to their remarkable collections, much of my research associated with this project would not have been possible. I learned a great deal in my interactions with various staff members from all of the various departments and to them I am deeply indebted for their hospitality and their willingness to share their ideas and time.

References Cited 1. B. F. Benz. (1999). On the origin, evolution and dispersal of maize. In: M. Blake, (Ed.), Development of agriculture and emergence of Formative Civilizations in Pacific Central and South America. The prehistory of the Pacific Basin. Seattle: Washington State University Press. pp. 25–38. 2. B. F. Benz, A. Long. (2000). Early evolution of maize in the Tehuacán Valley, Mexico. Current Anthropology, 41, 459–465. 3. M. Blake, J. E. Clark, B. Voorhies, G. Michaels, M. W. Love, M. E. Pye, A. A. Demarest, B. Arroyo. (1995). Radiocarbon chronology for the Late Archaic and Formative Periods on the Pacific Coast of Southeastern Mesoamerica. Ancient Mesoamerica, 6, 161–183. 4. V. G. Childe. (1939). Man makes himself. New York: Oxford University Press. 5. K. V. Flannery. (1973). The origins of agriculture. Annual Review of Anthropology, 2, 271–310. 6. K. V. Flannery, (Ed.). (1986). Guilá Naquitz. Archaic foraging and early agriculture in Oaxaca, Mexico. Orlando, FL: Academic Press. 7. F. O. Freitas, G. Bandel, R. G. Allaby, T. A. Brown. (2003). DNA from primitive maize landraces and archaeological remains: implications for the domestication of maize and its expansion into South America. Journal of Archaeological Science, 30, 901–908. 8. W. C. Galinat. (1988). The origin of corn. Agronomy, 18, 1–31. 9. I. Hodder. (1990). The domestication of Europe. Oxford, UK: Blackwell Publishers. 10. S. Johannessen, C. A. Hastorf, (Eds.). (1994). Corn and culture in the prehistoric New World. Boulder, CO: Westview Press. 11. Y. T. A. Kato. (1984). Chromosome morphology and the origin of maize and its races. Evolutionary Biology, 17, 219–253. 12. A. L. Kroeber. (1944). Configurations of culture. Berkeley: University of California Press. 13. P. C. Mangelsdorf. (1974). Corn: Its origin, evolution and improvement. New York: Harvard University Press. 14. Y. Matsuoka, Y. Vigouroux, M. M. Goodman, J. Sanchez, E. Buckler, J. Doebley. (2002). A single domestication for maize shown by multilocus microsatellite genotyping. Proceedings of the National Academy of Sciences of the United States of America, 99, 6080–6084. 15. B. McClintock, Y. T. A. Kato, A. Blumenschein. (1981). Chromosome constitution of races of maize [Constitución chromosoma de razas de maíz]. Chapingo, Mexico: Colegio de Postgraduados. 16. P. Phillips, G. R. Willey. (1953). Method and theory in American Archaeology: An operational basis for cultural-historical integration. American Anthropologist, 55, 615–633.

An Introduction to the Histories of Maize 17. D. R. Piperno, K. H. Clarey, R. G. Cooke, A. J. Ranere, D. Weiland. (1985). Preceramic maize in central Panama: Phytolith, pollen evidence. American Anthropologist, 87, 871–878. 18. B. D. Smith. (2005). Reassessing Coxcatlan Cave and the early history of domesticated plants in Mesoamerica. Proceedings of the National Academy of Sciences of the United States of America, 102, 9438–9944. 19. B. D. Smith. (2001). Documenting plant domestication: the consilience of biological and archaeological approaches. Proceedings of the National Academy of Sciences of the United States of America, 98, 1324–1326. 20. J. E. Staller. (2003). An examination of the palaeobotanical and chronological evidence for an early introduction of maize (Zea mays L.) into

21. 22. 23. 24.

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South America: A response to Pearsall. Journal of Archaeological Science, 373–380. G. R. Willey. (1964). An introduction to North American archaeology. Volume 1: North America. New York: Prentice-Hall Inc. G. R. Willey. (1971). An introduction to South American archaeology. Volume 2: South America. New York: Prentice-Hall Inc. G. R. Willey, P. Phillips. (1958). Method and theory in American archaeology. Chicago: University of Chicago Press. G. R. Willey, J. A. Sabloff. (1980). A history of American archaeology. San Francisco, CA: W. H. Freeman & Co.

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HISTORIES OF MAIZE Genetic, Morphological, and Microbotanical Evidence

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1 Differing Approaches and Perceptions in the Study of New and Old World Crops TERENCE A. BROWN Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom

Introduction 3 Different Emphases in New and Old World Agriculture 4 Different Perceptions of the Role of Science 6

The great advances that have occurred in recent years in understanding the origins, spread, evolution, and uses of maize have paralleled similar advances with the principal crops of Old World agriculture, namely wheat and barley. Although there has been extensive transfer of ideas and results, the two research communities have developed their work with some independence, leading to an interesting, and possibly informative, divergence in scientific approaches and perceptions. For example, work on the spread of maize cultivation has always been informed by a clear perception that the factors responsible for adoption of agriculture at a particular site are complex and multifaceted, and hence the factors operating at one site may be different to those at another site. In contrast, ideas regarding wheat and barley cultivation have developed within the context of the competing wave of advance and acculturation models for agricultural spread, as described by human geneticists. These models, with their emphasis on cross-continental events, tended to draw attention away from the different effects of local factors, which subsequently have received relatively little attention in Europe. This chapter explores the differing approaches and perceptions in the study of New and Old World crops and attempts to identify areas where greater cross-fertilization of ideas may be beneficial to the two research communities.

Glossary Amplified fragment length polymorphism (AFLP) A type of DNA sequence variation revealed by the polymerase chain reaction. Ancient DNA DNA preserved in ancient biological material. Mesolithic-Neolithic Transition A term used here to describe the period of Old World prehistory associated with a broad package of social and cultural changes that included adoption of agriculture in Southwest Asia. Mitochondrial DNA haplogroups Groups of related DNA sequences that indicate the genetic structure of human populations. Old World agriculture Used here to mean the agricultural system based on wheat, barley, and other crops that originated in the Fertile Crescent of Southwest Asia approximately 10,000 years ago. Postprocessualism A form of interpretative archaeology, which, among other things, rejects a positivist view of science. Predomestication cultivation A period during which the progenitors of a crop are managed as a distinct population that is not completely isolated, in a reproductive sense, from wild members of the species. Wave of advance A hypothesis that suggests agricultural spread into Europe was driven by large-scale migration of farmers in a southwest to northwest direction across the continent.

Histories of Maize

INTRODUCTION To an archaeologist, one of the most intriguing features of the development of agriculture is the way in which this process occurred independently and concurrently in different parts of the New and Old Worlds. To the casual observer, an equally intriguing example of independence and concurrence is provided by the way in which the archaeological study of agriculture has developed on the two sides of the

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Atlantic. The point is reflected by this book: of the 48 chapters presented on the prehistory, biogeography, domestication, and evolution of maize, only 2 come from groups located in countries outside of the Americas. One might suggest that a volume initially based on a symposium held at the Annual Meeting of the Society for American Archeology (SAA) might inevitably contain contributions that come predominantly from American archaeologists, but the geographical spread of the contributors to this volume does in fact give an accurate indication of where the vital research into the history of maize is being carried out. It is difficult to provide comparable data on the geographical spread of archaeologists working on the Old World crops, such as wheat and barley, because no equivalent symposium on the prehistory of these crops has been held in recent years. If such a symposium were held, then there would probably be a greater mixing of archaeologists from the New and Old Worlds, but a substantial majority of the contributors would be from Europe. And, although there would be notable exceptions, it is perhaps doubtful if many of the speakers or members of the audience from the SAA symposium on maize would speak at or attend a symposium on wheat and barley. Of course, it is not necessary for archaeologists to meet at conferences to exchange ideas, and there has always been an extensive intellectual interchange among groups working on the New and Old World crops, both through direct contacts and indirectly via the electronic and print media. Nonetheless, the degree of independence with which work on these two agricultural systems has developed has led to interesting, and possibly informative, divergences in approaches and perceptions. In this chapter, I attempt to draw out these divergences and (from a European perspective) to identify areas where cross-fertilization of ideas may be beneficial to the two research communities.

DIFFERENT EMPHASES IN NEW AND OLD WORLD AGRICULTURE The SAA symposium on “The Stories of Maize,” on which this book is based, is an interesting point from which to begin a consideration of the contrasts between the American and European approaches to prehistoric agriculture. The symposium organizers attempted, with considerable success, to draw together researchers addressing different aspects of maize, including its origins, spread, and evolution, the different roles and uses of the crop, and the plant’s social and symbolic significance. In combination, the presentations covered a huge range of research strategies, encompassing scientific techniques such as DNA, phytolith, and isotope analyses, archaeobotanical and biogeographical approaches, and ethnohistoric, ethnographic, and linguistic studies. The symposium ran for 4 sessions held over 2 full days of the SAA meeting, with papers presented by 46

regular speakers and 8 discussants. The audience—which numbered more than 200 at times—was mixed, and this was certainly not one of those symposia where the speakers speak mainly to themselves. In short, the symposium formed a central and important part of the SAA meeting as a whole. If a large symposium devoted to the archaeology of maize can be so successful and so well received at the major American archaeology conference, then why has there been no recent symposium devoted to the archaeology of wheat or barley at a major European conference? Or, to phrase the question differently, why should maize be considered a central research topic in the archaeology of the New World whereas wheat and barley are looked on as a specialist’s subject within European archaeology? I believe that the answer lies in a fundamental difference in emphasis in the way in which agriculture is studied in the New and Old Worlds. In the Americas, it is clear from the nature and success of the SAA symposium that the approach taken to the study of agricultural origins and development places major emphasis on the crops themselves. In Europe there is equal recognition of the central role agriculture played by the Southwest Asian crop assemblage—principally wheat and barley, but also comprising lentils, peas, flax, bitter vetch, and chickpea [34]—but the difference is that the origin and spread of agriculture is rarely looked on as an event in itself [33]. Instead, the adoption of agriculture is placed within a broader social context, originally called the “Neolithic Revolution” by V. Gordon Childe [7], but now more generally referred to as the “Mesolithic-Neolithic Transition.” Agriculture, therefore, becomes just one of a package of changes, including pottery and ground stone tools, that together constitute a significant step in human cultural evolution [32]. This explains why a proposal for a symposium on “The Histories of Wheat” would probably receive short shrift from the organizers of a major European archaeology conference and would not attract a particularly large audience. On the other hand, symposia on The MesolithicNeolithic Transition are frequently held, and although these adopt a broad approach, they inevitably include contributions from plant biologists in general and cereal geneticists in particular.

Reasons for the Difference in Emphasis Whether the notion of the Neolithic Revolution is reasonable as an interpretation of and means of studying the origins of agriculture in the Old World, and whether or not agriculture in the New World was part of a similarly broad and far-reaching set of social and cultural changes, are interesting questions, but not the ones I am raising here. The point I wish to explore is why there should be such a striking difference in emphasis in the New and Old Worlds. There are almost certainly a number of underlying causes to the differences in emphasis apparent today. One particu-

Differing Approaches and Perceptions in the Study of New and Old World Crops

larly fascinating question is the extent that notions regarding the singularity, or otherwise, of the invention of agriculture have played a role in the development of research into maize and wheat cultivation. In the New World, the natural distribution of teosinte in Mexico and Central America places a geographical limitation on the region where maize agriculture might have originated [23], but the initial interpretation, based on the substantial morphological and genetic variation displayed by modern maize, was that the crop was domesticated on multiple occasions [10, 18]. The alternative possibility, that maize has a single origin, has only really had strong supporting evidence since the publication in 2002 of analyses of microsatellite variation in maize cultivars and in wild teosinte populations; phylogeographical analysis of these data indicate that maize is monophyletic and arose from a single domestication in southern Mexico about 9000 years ago [20]. The study of maize archaeology has, therefore, developed with an open picture of the origins of the crop and hence without any strong basis for placing those origins within the social and cultural context of communities living in the region at the appropriate time. In contrast, for more than a decade, the prevailing view, based on various forms of genetic evidence, has been that the Old World crops were each domesticated once [34], a view that appeared to be confirmed in the later 1990s by examination of large amplified fragment length polymorphism (AFLP) datasets for wheat and barley [3, 14, 22]. Further, the distributions of the wild progenitors of the Old World crops indicated that their site(s) of domestication must fall within Southwest Asia, one of the regions of the world that has been subjected to the most intense archaeological survey. It is not surprising that the presumed singularity of agricultural origins was, therefore, linked with prevailing archaeological thought on the development of culture and technology in Southwest Asia. Once this connection had been made it was, perhaps, inevitable that Old World agriculture would become looked on, conceptually, as part of a broader social transition, and that the inherent importance of this transition would become linked, at least in the mind of the layman, to the guns, germs, and steel of the modern day [8]. In the New World, studies of agriculture have developed without such distractions. Interestingly, the notion of a single origin for maize has become prevalent just at the time that Old World researchers are beginning to reject the emphasis previously placed on single versus multiple origins as overly simplistic. This leads on from recognition that a single, geographically localized domestication for any Old World crop is inconsistent with the gradual transition from gathering to cultivation to domestication that is apparent in the archaeological record. In this regard, it has been suggested [28] that genetic monophyly might not reflect a single, localized domestication for a particular crop, but instead be caused by the emergence, following a more complex origin, of a superior landrace

5

from which all modern varieties are descended. Similarly, I have argued [17] that the genetic diversity of modern wheat supports the notion that this crop underwent a substantial period of predomestication cultivation, during which the crop was partially, but not completely, isolated in a reproductive sense from its wild cousins. Partial isolation entails that the crop be managed as a distinct population, but one into which there is some gene flow from neighboring wild plants, possibly from different parts of the natural range if cultivation of the predomesticated crop spread. Eventually, a part of the predomesticated crop might acquire full reproductive isolation, resulting in persistence of the morphological traits that are associated with domestication, simply as a result of cultivation spreading outside of the natural range of the wild plants [17]. Hypotheses such as these give a greater complexity to agricultural origins than is evident from the simple interpretation of genetic monophyly as an indicator of a single domestication. It could be argued that persistence of the spurious link between the genetic monophyly of a crop and its assumed domestication by a single community at a single point in time has held up progress in the study of Old World agriculture for a decade or more. Chapter 3 by Hugh Iltis suggests that this pitfall is avoided in the New World.

Outcomes of the Difference in Emphasis How have the different perceptions of agriculture influenced research in the New and Old Worlds? One outcome that appears to be having a substantial impact on the development of research is the differing levels of importance applied to regionality in studies of the spread and subsequent secondary development of maize and wheat cultivation. In the Old World, particularly in Europe, the trajectories by which the cultivation of wheat and its associate crops spread have been traced by identifying the earliest appearance in different regions of the trappings of agriculture (e.g., quern stones for grinding grain, preserved remains of the crops themselves) and other artifacts looked on as indicative of the cultural package of which agriculture formed a part. This work has defined two paths for the spread of agriculture into Europe: one follows the Danube and Rhine valleys through the center of the continent and into the northern European plain and is associated with Linearbandkeramik pottery, and the second takes a coastal route through Greece and Italy to Iberia and eventually Britain [4, 5, 25]. Since the initial description of these trajectories in broad-brush strokes, more detailed investigation, based largely on new excavation, has defined in greater detail the time of arrival and the local development of agriculture at different points within Europe [13]. This work has identified clear and important regional differences in the way in which agriculture became established and was exploited throughout Europe, but the implications and importance of this regionality have

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struggled to assume the high position that they warrant on the European archaeological agenda. This is because research in the Old World has been dominated by discussions about the human dynamics responsible for the spread of agriculture [26]. Largely but not exclusively based on human genetics, this discussion was initiated by the publication of Luca Cavalli-Sforza’s research into the geographical distribution of nuclear allele frequencies in human populations [6]. Although this work was global in coverage, particular interest was stimulated by the distribution patterns in Europe because these revealed the existence of a genetic gradient across the continent, from southeast to northwest (or vice versa). The date at which this gradient was set up cannot be determined from the genetic data, but the coincidence between the human migration implied by this gradient and the movement of humans that could have accompanied the spread of agriculture, led to the genetic data being used as convincing evidence that agriculture arrived in and was carried through Europe by a human wave of advance, echoing ideas that had been current in European archaeology since the mid-1960s [1, 2]. The wave of advance model has clear and important implications for issues such as demographic change in prehistoric Europe [33], and perhaps explains why the term “Neolithic Revolution” gained such popularity. The wave of advance model also implies uniformity in the manner in which agriculture arrived in different parts of Europe, and even suggests that the subsequent development of agriculture may have followed a similar pattern throughout the continent, in that the same cultural group, regardless of location, oversaw this development. Against this background, regional variations apparent in the archaeological record become of limited importance, on the assumption that they are variations on a theme. The balance is becoming redressed, but only as the result of a debate among different camps of human geneticists that has itself drawn attention away from the more specific issues regarding agricultural spread. The debate was engendered first by studies of mitochondrial DNA haplogroups, which, being inherited solely through the female line and not being subject to recombination, are more amenable than nuclear alleles to the type of population and phylogenetic analyses needed to infer the patterns of past migrations [31]. This work has thrown the wave of advance model into doubt by showing that less than 10% of modern Europeans are descended from individuals likely to have moved into Europe at the time that agriculture arrived [27]. A similar downgrading of any wave of advance is also the outcome of studies of genetic markers on the Y chromosome [29]. Only in the past few years has it been possible to reconcile the human genetic data with the notion that that there are many different ways by which agriculture can diffuse from one point to another, ranging from total displacement of the nonagricultural population at one extreme to adoption of agriculture solely by transfer of technology with no popula-

tion movement at the other [35]. Once this point has been accepted it is a small step to the realization that across a landmass the size of Europe, with the environmental and cultural variability found across the continent, the spread of agriculture, and its subsequent local development, could have been a highly variable and regional process. Research into Old World agriculture has, therefore, reached a stage where regionality, after being buried under broader debates for more than a decade, is now reemerging as a central issue. The contrast with the situation in the New World is striking, as this volume amply illustrates. The specific information presented in many of these chapters on maize cultivation in regions that, on occasion, are just a few hundred square kilometers in size provides a picture of New World agriculture substantially richer than anything that is available for much of Europe. Of course, a converse to the European situation, in which an emphasis on regionality is allowed to obscure the bigger picture regarding the spread of agriculture, would be equally debilitating for the development of research, but this has also been avoided in the New World. The time of arrival of maize cultivation in most parts of North and South America is well understood [12, 19, 24], and although genetic data have so far been relatively underexploited as a means of studying crop movement, the original work by Barbara McClintock and colleagues based on chromosome morphologies [21] is gradually being supplemented by more modern studies of DNA markers and sequences [9, 20]. In this regard, the successful recovery and analysis of ancient DNA from preserved maize cobs [9, 11, 16] points a promising way forward, the use of archaeological remains enabling studies of the prehistoric spread of maize to be based on specimens whose biogeography has not become complicated by the movement of genotypes that has occurred during the post-Columbian period.

DIFFERENT PERCEPTIONS OF THE ROLE OF SCIENCE I have argued that the interpretation of Old World agriculture as part of a cultural package is one of the underlying reasons for the differences in the development of agricultural studies in the New and Old Worlds. I have also suggested that human genetics have diverted thought in Europe from the regional issues that have received greater attention in the New World. One final question is the extent to which the prevailing academic climate has influenced agricultural research in the Old and New Worlds. Over the past 25 years, the most significant event in academic archaeology has been the rise of postprocessualism. Adoption of the set of ideas that make up postprocessualism has reinvigorated archaeological theory, particularly with regards to the establishment of agriculture in Europe [15], but this reinvigoration has involved a move away from a

Differing Approaches and Perceptions in the Study of New and Old World Crops

scientific approach to archaeology. Postprocessualism does not reject science itself, it merely rejects the way science is practiced [30]; but the result is the same: the scientific contribution to archaeology is deemphasized. One outcome is that academic archaeology, particularly in the U.K., is currently divided into two camps, the members of which, often being faculty colleagues, may talk to one another, but who rarely establish intellectual contact. Science-based archaeology follows its own agenda and is often uninformed by the work of theoreticians, and vice versa. In fact, agriculture is one area where science and theory have maintained a reasonably productive relationship, as evinced by the manner in which science has adapted to the notion of agriculture as part of a cultural package. But the division of archaeology into different cultures is clearly detrimental to the development of any area of the subject, and although these dangers are recognized, especially among those who devise undergraduate syllabuses, it will be several years before archaeology in the U.K. will be able move forward again as a unified discipline. This is perhaps the main reason why a symposium equivalent to “The Stories of Maize” will probably not be held on Old World agriculture in the near future. A clear feature of research into New World agriculture is a mutual acceptance, understanding, and appreciation of the different forms of archaeological research, from the physical, biological, and social sciences through to linguistics, ethnohistory, and ethnography. It is debatable whether, at present, the same degree of intellectual fusion could be achieved among the various approaches to the study of Old World agriculture. Until this problem is solved, the crops themselves will not assume the central role in archaeological studies of Old World agriculture that maize plays in the New World, and the emphasis in Europe will continue to be on agriculture as part of a broader cultural package. But this is not necessarily a reason for discontent. A nonuniform approach on the two sides of the Atlantic becomes beneficial when looked on as two parallel but different experiments in the study of agriculture. Comparisons of our successes and failures can then help both groups make progress toward their goals.

Acknowledgments I thank Keri Brown for his comments on this paper. The opinions expressed are solely my own.

References Cited 1. A. J. Ammerman, L. L. Cavalli-Sforza. (1971). Measuring the rate of spread of early farming in Europe. Man, 6, 674–688. 2. A. J. Ammerman, L. L. Cavalli-Sforza. (1973). A population model for the diffusion of farming into Europe. In: A. C. Renfrew, (Ed.), The explanation of culture change: Models in prehistory. London: Duckworth. pp. 343–358.

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3. A. Badr, K. Müller, R. Schäfer-Pregl, H. El Rabey, S. Effgen, H. H. Ibrahim, C. Pozzi, W. Rohde, F. Salamini. (2000). On the origin and domestication history of barley (Hordeum vulgare). Molecular Biology and Evolution, 17, 499–510. 4. G. Barker. (1985). Prehistoric farming in Europe. Cambridge: Cambridge University Press. 5. P. Bogucki. (1996). The spread of early farming in Europe. American Scientist, 84, 242–253. 6. L. L. Cavalli-Sforza, P. Menozzi, A. Piazza. (1994). The history and geography of human genes. Princeton: Princeton University Press. 7. V. G. Childe. (1935). Changing methods and aims in prehistory. Proceedings of the Prehistoric Society, 1, 1–15. 8. J. Diamond. (1997). Location, location, location: The first farmers. Science, 278, 1243–1244. 9. F. O. Freitas, G. Bandel, R. G. Allaby, T. A. Brown. (2003). DNA from primitive maize landraces and archaeological remains: Implications for the domestication of maize and its expansion into South America. Journal of Archaeological Science, 30, 901–908. 10. W. C. Galinat. (1988). The origin of corn. In: G. F. Sprague, J. W. Dudley (Eds.), Corn and corn improvement, 3rd ed. Madison, WI: American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. pp. 1–31. 11. P. Goloubinoff, S. Pääbo, A. C. Wilson. (1993). Evolution of maize inferred from sequence diversity of an Adh2 gene segment from archaeological specimens. Proceedings of the National Academy of the Sciences of the United States of America, 90, 1997–2001. 12. M. M. Goodman. (1978). Historia e origem do milho. In: E. Paterniani (Ed.), Melhhoramento e Producao do Milho no Brasil. São Paulo, Brazil: Fundação Cargil. pp. 30–65. 13. D. R. Harris (Ed.). (1996). The origins and spread of agriculture and pastoralism in Eurasia. London: UCL Press. 14. M. Heun, R. Schäfer-Pregl, D. Klawan, R. Castagna, M. Accerbi, B. Borghi, F. Salamini. (1997). Site of einkorn wheat domestication identified by DNA fingerprinting. Science, 278, 1312–1314. 15. I. Hodder. (1990). The domestication of Europe. Oxford: Blackwell. 16. V. Jaenicke-Després, E. S. Buckler, B. D. Smith, T. Gilbert, A. Cooper, J. Doebley, S. Pääbo. (2003). Early allelic selection in maize as revealed by ancient DNA. Science, 302, 1206–1208. 17. M. K. Jones, T. A. Brown. (In press). Selection, cultivation, and reproductive isolation: A reconsideration of the morphological and molecular signals of domestication. In: T. Denham, J. Iriarte, L. Vrydaghs, (Eds.), Rethinking agriculture: Archaeological and ethnoarchaeological perspectives. London: UCL Press. 18. T. A. Kato. (1984). Chromosome morphology and the origin of maize and its races. Journal of Evolutionary Biology, 17, 219–253. 19. P. C. Mangelsdorf. (1974). Corn: Its origin, evolution and improvement. New York: Harvard University Press. 20. Y. Matsuoka, Y. Vigouroux, M. M. Goodman, J. Sanchez, E. Buckler, J. Doebley. (2002). A single domestication for maize shown by multilocus microsatellite genotyping. Proceedings of the National Academy of the Sciences of the United States of America, 99, 6080–6084. 21. B. McClintock, T. A. Kato, A. Blumenschein. (1981). Chromosome constitution of the races of maize: Its significance in the interpretation of relationships between races and varieties in the Americas. Chapingo, Mexico: Colegio de Postgraduados. 22. H. Özkan, A. Brandolini, R. Schäfer-Pregl, F. Salamini. (2002). AFLP analysis of a collection of tetraploid wheats indicates the origin of emmer and hard wheat domestication in southeast Turkey. Molecular Biology and Evolution, 19, 1797–1801. 23. D. R. Piperno, K. V. Flannery. (2001). The earliest archaeological maize (Zea mays L.) from highland Mexico: New accelerator mass spectrometry dates and their implications. Proceedings of the National Academy of the Sciences of the United States of America, 98, 2101–2103.

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24. K. O. Pope, M. E. D. Pohl, J. G. Jones, D. L. Lentz, C. von Nagy, F. J. Vega, I. R. Quitmyer. (2001). Origin and environmental setting of ancient agriculture in the lowlands of Mesoamerica. Science, 292, 1370–1373. 25. T. D. Price (Ed.). (2000). Europe’s first farmers. Cambridge: Cambridge University Press. 26. C. Renfrew. (2000). Towards a population prehistory of Europe. In: C. Renfew, K. Boyle (Eds.), Archaeogenetics: DNA and the population history of Europe. Cambridge: McDonald Institute for Archaeological Research. pp. 3–11. 27. M. Richards. (2003). The Neolithic invasion of Europe. Annual Review of Anthropology, 32, 135–162. 28. F. Salamini, H. Özkan, A. Brandolini, R. Schäfer-Pregl, W. Martin. (2002). Genetics and geography of wild cereal domestication in the Near East. Nature Reviews. Genetics, 3, 429–441. 29. O. Semino, G. Passarino, P. J. Oefner, A. A. Lin, S. Arbuzova, L. E. Beckman, G. De Benedictis, et al. (2000). The genetic legacy of Paleolithic Homo sapiens sapiens in extant Europeans: A Y chromosome perspective. Science, 290, 1155–1159. 30. M. Shanks, C. Tilley. (1992). Reconstructing archaeology: Theory and practice, 2nd ed. London: Routledge.

31. B. Sykes. (2000). Human diversity in Europe and beyond: From blood groups to genes. In: C. Renfew, K. Boyle, (Eds.), Archaeogenetics: DNA and the population history of Europe. Cambridge: McDonald Institute for Archaeological Research, Cambridge, 2000. pp. 23–28. 32. J. Thomas. (1993). Discourse, totalisation and the “Neolithic.” In: C. Tilley (Ed.), Interpretative archaeology. London: Berg. pp. 357–394. 33. J. Thomas. (1996). The cultural context of the first use of domesticates in continental Central and Northwest Europe. In: D. R. Harris (Ed.), The origins and spread of agriculture and pastoralism in Eurasia. London: UCL Press. pp. 310–322. 34. D. Zohary. (1996). The mode of domestication of the founder crops of Southwest Asian agriculture. In: D. R. Harris, (Ed.), The origins and spread of agriculture and pastoralism in Eurasia. London: UCL Press. pp. 142–158. 35. M. Zvelebil. (2000). The social context of the agricultural transition in Europe. In: C. Renfew, K. Boyle (Eds.), Archaeogenetics: DNA and the population history of Europe. Cambridge: McDonald Institute for Archaeological Research. pp. 57–79.

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2 Maize in the Americas BRUCE F. BENZ Biology Department, Texas Wesleyan University, Ft. Worth, Texas

Purpose and Scope of Review 9 Introduction 10 Juxtaposing the Archaeological and Genetic Evidence for Early Maize 18

South America. Hypotheses abound, and evidence indicates these landraces are the product of culturally prescribed selection for desired agronomic and culinary attributes. Radiocarbon contemporaneity Radiocarbon dates whose uncertainty (sigma or standard deviation) overlaps such that their probability of being different is not expected by chance. Radiocarbon dates that estimate the same age. Speciation Macroevolution; the evolution of new species. Teosinte An English term adapted from the Nahuat “teocintli” (good or evil grain) used widely to refer to the seven taxa of wild grasses that are closely related to maize.

Glossary Agriculture The dependence of human populations on domesticated plants or animals, or both. Bottleneck Demographic process in which the number of reproductive individuals within a population is reduced provoking a reduction in the population’s genetic variation. Founder population. Domestication The process of taming plants and animals to facilitate their usefulness to humans. The evolution of a mutualistic relationship of the plant or animal on human behaviors that ensure their continued survival. Domestication syndrome A syndrome is a suite of characters that together reflect a response to some action. In the case of human behavior, a domestication syndrome refers to morphogenetic characters such as rigid, nondisarticulating rachis; soft, and sometimes disarticulating chaff (glumes, lemma, and palea) surrounding the grain; reduced defensive traits such as the reduction of silica in the epidermal tissues or defensive secondary metabolites; monopodial branching, or lack of branching, resulting in production of one or only a few inflorescences (fruits); uniform germination of the grain or seeds on planting and uniform ripening on harvesting; uniformity of morphological characteristics of the plant; inflorescence; and fruit or seeds that facilitate harvesting. Epistasis Multiple genes affecting a single trait. Evolutionary rate Amount of morphological or genetic change over time. Landraces Distinct populations of traditional varieties with limited geographic range cultivated in North and

Histories of Maize

Biological and archaeological evidence concerned with the early evolution of maize is reviewed in this chapter in an attempt to resolve conflicting interpretations about the process and its antiquity. Estimates of bottleneck size derived from molecular biology and archeology are internally consistent; domesticated populations were small, perhaps for a few hundred generations during which maize’s genetic diversity was significantly, perhaps dramatically reduced. Estimates of the antiquity of the domestication process from molecular biology are internally consistent yet antedate some of the archaeological evidence.

PURPOSE AND SCOPE OF REVIEW Archaeological evidence for plant domestication provides critical documentation of the human manipulation of plant population genetics: absolute dating and cultural context. The focus of archaeological study of maize’s origin and evolution has been the temporal documentation of the domesticates’ initial appearance. There has been little archaeological concern for documenting sustained agricul-

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tural selection—continued domestication—after recording the initial steps humans took to select for traits that distinguish the domesticated species from its wild ancestor. Archaeological evidence for maize domestication throughout the Americas is abundant. Yet, there is little evidence on domestication process [2]. This stems in part from the historical misidentification of maize’s ancestor [26] and from archaeological focus on “firsts” and less interest in the processes of maize production and population manipulation. Three lines of evidence have been exploited by archaeologists to document the domestication process: study of inflorescence morphology, pollen size, and phytolith shape and abundance. The evidence each provides is discussed in the attempt to winnow salient facts about maize’s domestication. However, before discussing archaeological study of maize domestication and agriculture in the Americas, I review the biological efforts to understand maize domestication. My choice in focusing on biological evidence first is biased by my belief that biological evidence has been instrumental in directing our attention at the appropriate archaeological questions but recognizes that most biological research on maize produces hypotheses that can lead only to inferences about the historical cultural processes that produced maize. Archaeological evidence, in contrast, is uniquely suited to testing these biological hypotheses.

INTRODUCTION As mentioned previously, much of the archaeological evidence has documented only when a particular morphological or allelic manifestation (phenotype) of domestication first appears in the archaeological record. The biological community has pursued other evidence that contemplates documenting processes associated with domestication. Molecular biology has focused not only on the genes attributed to domestication but has used these and numerous other genetic markers to discern how humans affected teosinte populations in their search for more productive or more readily harvestable phenotypes. The biological focus on domestication genes has touched on two areas of biological importance for understanding human behaviors toward plant harvesting and production: 1) the amount of time in human generations spent manipulating teosinte to manage the harvesting process that eventually domesticated teosinte and ensured a more productive and reliably harvested phenotype; and 2) the size of teosinte and maize populations that humans focused on to achieve these goals. The results of the latter have been more cogent and consistent than the former; although, the results of each are worthy of review not only for the trends they document but also for pointing out human behaviors that can be inferred from them. The appearance of domestication syndrome traits has long been the focus of archeological inquiry [23]. The first,

or earliest appearance of a glume or rachis fragments in the archeological record is taken as a horizon marker, a harbinger of change in human behavior. With a few exceptions, study has rarely focused on the quantitative changes in maize ear morphology to detect and document the rate of change in political, social, or technological adaptations of the cultivators. Instead, research has sought to document difference in assemblages that attribute such changes to environmental or cultural factors. Fortunately, this is changing. Attempts are being made (this volume contains numerous examples, e.g., Chapters 7 and 31) to document the rate of evolutionary change in maize that is inextricably linked to human behavioral change and that will permit one to identify the critical periods during which human effort and focus changed. The possibility of asking these questions is practical and possible using morphological traits of the corn cob and genetic markers and should be possible using phytoliths and pollen. The chronological placement of domesticated plants, maize in particular, has been fraught with challenges. Archaeological context provided the bias for a long held misconception about the age of domesticated maize in the Tehuacan Valley because its age was inferred from associated radiocarbon determinations whose reliability for estimating corn cob age was low. Attempts to reconcile differences between the age of maize specimens on which accelerator mass spectrometry (AMS) dates have been successful and their contextually associated radiocarbon dates have produced mixed results [44]. Fortunately, the morphology of the remains of maize argues that its initial domestication occurred sometime during the Middle to Late Archaic Periods in Mesoamerica before maize’s early appearances at Guila Naquitz. Chronological determination of maize’s origin has long been a contentious issue. The issue stems not so much from the vagaries of relative dating as from the different types of archaeological evidence brought to bear on the subject. Pollen was long the chink in the armor of George Beadle’s teosinte hypothesis—the pollen from the Bellas Artes pollen core was clearly maize and believed to be more than 80,000 years old. Mangelsdorf [26, p. 183] believed that wild maize existed long before domesticated maize. Much has been written since then to counter this argument. Pollen and phytoliths have kept the antiquity of maize controversy alive [38, 40, 41]. Phytoliths are more readily extracted from archaeological sediments than pollen, even though identification is more challenging than pollen simply because the shapes of these epidermal silica inclusions are more varied and less distinctive than maize pollen. Simultaneous study of these two types of botanical evidence has produced intriguing results that will continue to drive the search for pre-2000 BC maize in Central and South America. Pollen and phytoliths are eminently suited for documenting early agriculture in and around lakes and in

Maize in the Americas

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rock shelters and open sites inhabited by humans during this critical period. The motivation for writing this chapter should be made clear. Knowing that the evidence for maize agriculture in Tehuacan is unequivocal and knowing that the domesticated teosinte inflorescences from Guila Naquitz were of domesticated plants, the time depth of the human manipulation of teosinte begs for resolution. Juxtaposing the genetic evidence with the archaeological, geochronological, and paleoenvironmental evidence and literature should help resolve the controversy surrounding initial domestication and dispersal.

Genetic Evidence of Teosinte Domestication The polemic surrounding the ancestor of maize was resolved using molecular techniques first deployed to understand taxonomic relationships in the genus Zea. Isozymes [13] clearly indicate that maize and teosinte are closely related, as crossing/hybridization relationships demonstrated long before [26, 28]. Significant breakthroughs followed the development of molecular techniques, which enabled the identification of genes involved in the domestication process [15, 16, 17]. Early attempts to compare genetic relationships between maize and teosinte [18, 24] focused on genes that had little obvious involvement in the domestication process; yet, even they demonstrated evidence of human manipulation of teosinte populations. Simultaneous efforts focused on mapping the genes that distinguish maize and teosinte [15, 16]. Doebley identified at least five regions of the Zea genome that were involved in maize’s speciation [14]. Each of these genes produces a phenotype that is a part of the domestication syndrome. And in some cases, the gene’s postulated actions appear to be epistatic on other characters of the domestication syndrome (except for Tga1 [50]). One of these genes affects plant architecture in the way typical of other domesticated cereals (the so-called domestication syndrome [23]) that affects apical dominance thereby reducing lateral branch lengths and ear number per plant. Teosinte is a highly branched plant (Figure 2-1) with numerous inflorescences protected in the axil of leaves on the main stem and branches. Maize typically produces one or at most two branches, each with only one or, infrequently, two or more inflorescences. Molecular mapping and expression studies identified the teosinte branched 1 (Tb1) gene as responsible for the branching difference between maize and teosinte and is epistatic on other domestication syndrome traits such as paired spikelets. Differences in seed dispersal between wild Zea and maize are complex. They encompass not only the development of “free-threshing” grain but the development of a tough, rigid rachis that will tenaciously hold the grain until it ripens and the development of protective husks surrounding the rigid

FIGURE 2-1 Author with two teosinte plants (Zea mays ssp. parviglumis Iltis and Doebley) along roadside in Balsas region of southern Mexico. Photo taken March 2003. (Courtesy of Bruce Benz)

rachis with attached spikelets harboring ripening grain as well. So far, the gene(s) responsible for rachis rigidity in maize remain(s) unidentified. However, a gene for freethreshing grain has been identified. In teosinte the grain is tightly enclosed within a cupulate fruitcase. This fruitcase is composed of a segment of the stiff, lignified, silicaimpregnated rachis (the cupule) and lower glume of the spikelet. The grain of teosinte is neither visible nor easy to liberate from the highly dispersible fruitcase. Maize grains are exposed within the spikelets but are protected by the whorls of leaf sheaths developing from the stem beneath the ear. The grains are otherwise unprotected though as the spikelets have emerged from the cupule and borne at a right angle to the axis of the inflorescence, they have become more readily harvested. Wang and colleagues [50] have demonstrated that this morphological difference is the result of a single nucleotide difference between maize and teosinte. Teosinte (Zea luxurians) grain has high nutritional value [22, 24, 26]. With higher total nitrogen and methionine content than maize, teosinte is purported to be preferred over maize by livestock (Hernandez Xolocotzi, personal communication). There is no difference in lysine, tryptophan, or

12

B. F. Benz

niacin, however. Maize, like many cereal grains, is deficient in two critical amino acids, lysine and tryptophan, which leads to nutritional deficiencies among populations with little dietary diversity and high dependence on maize. Maize appears to have a higher fat content than teosinte. Maize, like other cereals, possesses a wealth of genetic variation for carbohydrate storage: dent, flint, flour, and sweet are but four phenotypes produced by a complex metabolic pathway affecting the way glucose is stored in the grain’s endosperm. The nutritional value of the grain has been subject to human selection [24, 26, 46, 49] over the millennia since domestication. Jaenicke-Deprés and colleagues and Whitt and coworkers documented genetic variation in starch and protein [25, 49] storage enzymes that demonstrate that human selection has significantly reduced DNA sequence polymorphism in maize over teosinte. Traits associated with the domestication syndrome that currently lack genetic documentation of human manipulation include rachis rigidity (the disappearance of natural rachis disarticulation), paired spikelets, increased grain size, and polystichy, all traits that are present in the earliest archaeological material of domesticated teosinte [3–5]. Numerous reports identify a plethora of genetic loci in maize that were affected by humans imposing stringent selection pressures on the descendants of wild Zea mays ssp. parviglumis [25, 53].

Genetic Evidence of Population Manipulation The search for the genetic basis of maize’s difference from teosinte yielded understanding about the process of maize domestication. Molecular biologists document the genetic changes responsible for the domestication syndrome traits, but more critically, they have also posed and answered questions about the length of time humans have intervened in teosinte populations and the intensity with which subsequent manipulation of maize populations affected morphological and agronomic change to satisfy human needs. Gene sequence comparisons document population bottlenecks. Such bottlenecks occur among extant traditional agriculturalists [39] and should be expected to have occurred among pre-Hispanic and historical agriculturalists as well. The model of neutral evolution applied to such comparisons posits mutation as the raw material and genetic drift as the prime mover for genetic change. This model, applied to gene sequences, serves as a means of calculating the amount of genetic change expected to occur by mutation that serves as the baseline for determining how much time was necessary for such genetic differences to have occurred. Comparing genetic sequences between wild and domesticated populations permits statistical testing of this neutral model. Such models also permit statistical testing of hypotheses [18, 24, 46–48, 52] about the length of time humans have

experimented with teosinte populations, the intensity of human selection, and of effective population sizes [7]. Numerous studies [18, 22, 24, 46–48, 50–53] have estimated the effective population size and bottleneck duration from gene sequence data. Their estimates assume that random genetic change can mimic a molecular clock that, in turn, describes the structure and behavior of ancestral populations before speciation. Some genes are more suited to the task than others. First, the gene must be neutral, that is, it can show no clear evidence within its DNA sequence that shows significant evidence of systematic fixed differences between taxa. Second, the sequences must exhibit systematic variation demonstrating that ancestor and domesticate are in separate lineages. Third, the number of mutations or segregating sites should be roughly similar among populations. The Alcohol Dehydrogenase 1 (adh1) locus studied by Eyer-Walker and colleagues [18] fits these assumptions. To calculate the size of the bottleneck, the authors assumed that the first successful attempt to domesticate teosinte took place roughly 7500 years ago. Based on this assumption Eyer-Walker provided three estimates of the size of the bottleneck: 20 individuals if the duration of the bottleneck lasted 10 years, 1157 individuals if the bottleneck lasted 500 years, or 16,588 individuals if the bottleneck lasted for 7500 years. Assuming that the domestication bottleneck lasted for 2800 years (from 7500 to 4700 years ago—incorrectly using radiocarbon years for sideral time), the time from estimated domestication to maize’s appearance in Tehuacan, the bottleneck involved 5600 plants, a number roughly equivalent to 2 plants per year providing seed for subsequent plantings. If the prehistoric population size of teosinte (Zea mays ssp. parviglumis) was roughly 940,000 plants, as estimated by similar methods (estimate of gene sequence polymorphism in Zea mays ssp. parviglumis), then the bottleneck represented only 6% of the long-term population of teosinte. Hilton and Gaut [24] derived additional estimates of the population bottleneck on the basis of a nonessential seed storage protein—globulin 1 (glb1). The major difference from the previous work is that glb1 shows no fixed nucleotide differences between maize and Z. mays ssp. parviglumis suggesting the two taxa are closely related. Coalescent simulations of the genetic bottleneck corroborate the estimates by Eyer-Walker and colleagues [18] of the size of the maize founder population. If the bottleneck lasted 10 generations, the founder population may have consisted of as few as 7 individuals. If duration of the bottleneck lasted 100 generations, the population might comprise less than 70 individuals; if it lasted 1000 years, the bottleneck was 659 individuals; and if it lasted 2800 years, the total size of the founder population was only 1830 individuals, roughly 1 individual per generation (Table 2-1). Inclusion of Tripsacum in the studies of adh1 and glb1 sequence diversity also permitted the authors to make the

Maize in the Americas

TABLE 2-1 Estimated Population Sizes of Genetic Bottleneck Occurring with the Domestication of Maize. Effective population size and the size of the bottleneck are correlated. The values in the table are of two types: the duration of the bottleneck is assumed, whereas the size of the bottleneck is predicted for adh1, glb1, the 12 genes on chromosome 1, and the single nucleotide polymorphisms, whereas the size of the bottleneck is assumed and the duration of the bottleneck predicted for tb1. In either case, the size of the bottleneck and its duration are strongly correlated. Gene/loci adh1

Duration of bottleneck in years

Size of bottleneck ne

10 500 7500 2800a

20 1157 16,588 5600

[18]

[24]

Reference

glb1

100

70

12 genes

100

892

Chromosome 1

500 2800

2500 12,500

SNPs

2800

3500

[53]

tb1

313 1023

1000 10,000

[51]

185

200

Morphology

[46, 47, 48]

[7]

a

The estimated time difference between the first domesticating genetic change and the last efforts of domesticating selection (7500–4700 BP), see text.

following observation: Tripsacum and Z. mays ssp. mays possess no shared sequence polymorphisms indicating that maize did not evolve as the result of a hybridization between a member of the genus Zea and Tripsacum. Although the study of gene sequence divergence provides useful clues to the processes involved in maize domestication hypothesized by others, the authors conclude that “there are no good independent estimates for the true duration of the original domestication event” [24, p. 870]. White and Doebley [52] examined sequence diversity of a gene associated with one of the genetic marker loci (quantitative trait loci [QTL]) implicated as one of the domestication syndrome traits [15, 16]. In this, and the two aforementioned studies of sequence divergence, the amount of sequence polymorphism in maize is significantly less than that of its ancestor. This reduction in polymorphism should be expected of most speciation events resulting from domestication. The speciation process involves one or, at most, a few individuals diverging from the ancestral population because they exhibit some beneficial trait that selection can focus on taking with them in the process only a fraction of the total genetic variation present in the ancestral popula-

13

tion. The first study of ancient DNA from maize performed by Goloubinoff and colleagues [20] found quite different results. Sequences analyzed from three pre-Columbian maize samples, five modern maize samples, and one sample each from four different Zea species and Tripsacum pilosum, showed an equivalent amount of sequence diversity between pre-Columbian and modern maize. These results suggest the latter had not acquired different sequence polymorphism through drift or recombination since evolving from their last common ancestor. It is possible that small number of samples might explain the lack of difference. Wang and colleagues [51] also examined the relationships between domesticated maize and two of maize’s closest wild relatives, the Mexican annual teosintes (Z. mays ssp. parviglumis and Z. mays ssp. mexicana), using the tb1 gene that Doebley’s [51] laboratory had documented as a crucial locus in the transformation of teosinte into maize. Wang and colleagues were able to sequence the entire tb1 gene sequence and ascertain that the main differences between maize and Z. mays ssp. parviglumis are located in the nontranscribed region—the regulatory region—of the gene, not in the transcribed region. Additional insights were gained from this. The estimated time of the domestication bottleneck is estimated to have occurred over a 300- to 1000year time span. This estimate is based on selection coefficients between 0.04 and 0.08. (These are equivalent to relative annual differences in fitness of 100 maize-like alleles to 94 or 92 teosinte alleles, respectively). Matsuoka and colleagues corroborated Zea mays ssp. parviglumis’ identity as maize’s closest wild relative using microsatellite coverage of the entire genome instead of focusing on a single gene region [29]. Microsatellites document a single origin for maize from Zea mays ssp. parviglumis and date the time of divergence between these two species somewhere between 5689 and 13,093 generations before the present (which the authors equate to years). This 95% confidence interval surrounds the estimated average time of separation of 9188 years BP or ca. 7200 BCE. This places the highest probability of the first human domesticating selection activities on teosinte as having occurred more than 3500 years before maize was incorporated into the Tehuacan cave deposits. The phylogenetic results of Matusoka and colleagues [29] also indicate a clear diversification of maize in central Mexico and offer a crucial evolutionary hypothesis of maize’s spread throughout the Americas from the highlands of central Mexico. “[T]he phylogenies and PCA suggest two lineages or paths of dispersal. One path traces through western and northern Mexico into the southwestern U.S. and then into the eastern U.S. and Canada. A second path [presumably later] leads out of the highlands to the western and southern lowlands of Mexico into Guatemala, the Caribbean Islands, the lowlands of South America, and finally the Andes Mountains” [29, p. 6084].

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B. F. Benz

Even though the number of collections used to generate this phylogeny is a magnificent effort, its sample of maize is noticeably depauperate: 264 plants represent more than 300 landraces cataloged for the Americas, in which only 75% of the Mexican races are included. Yet, the proposed routes of dispersal lend credence to previous hypotheses concerning dispersal into North America north of Mexico, Central America, and the Central–South American connection [28], although it contradicted previous hypotheses concerning the phylogeny of Mexican maize [3]. It also created a polemic surrounding the altitudinal location of maize’s domestication instead of resolving such a debate. Though the races identified as basal in the cladogram and cluster diagram by Matsouka and colleagues [29] are all collections occurring today above 1900 meters, the populations of annual teosinte consistently showing greatest genetic similarity to Mexican maize currently grow at elevations between 950 and 1400 meters. San Marcos, Coxcatlan, and El Riego caves in the Tehuacan Valley are all located at elevations between 1100 and 1300 meters. Only Guila Naquitz, with only three corn cobs found dating on or before 4250 BCE, is located at 1926 meters above sea level [36], whereas the Tamaulipas caves are located at 1500 meters. It seems likely that the sample taken by Matsouka and colleagues missed some of the extant basal lineages, because samples representing these lineages were not included in the study or these lineages are extinct. The biogeography of the so-called basal lineages identifies only high altitude populations some of which are traditional varieties still cultivated in the uplands (most are recent INIFAP collections) where isolation and extreme habitats have limited introductions, whereas the lowlands have experienced more extensive and rapid turnover of landraces due to the ease of invasion by higher yielding varieties [1]. If this hypothesis is accurate, one would also expect that all the recently made collections included in the study by Matsuoka and colleagues would tend to show up toward the base of the phylogeny because they have retained the greatest number of shared derived alleles with ancient varieties, whereas those collected during the National Research Council efforts in the 1940s and 1950s would have lost some variation in the process of gene bank storage and repeated increases of gene bank collections. Supporting data available online suggest that most of the collections identified as basal were made recently by members of the Instituto Nacional Forestal y Agropecuario or other institutions. Work on three domestication-related genes and single nucleotide repeats has shed even greater light on the phylogenetic relationships within Zea mays [49, 51, 53]. Whitt and colleagues [49] identified vital genetic differences between maize and teosinte responsible for the changes in the structure of starch storage in maize grains from study of a variety of inbreds, a few landraces, teosinte populations, and a few varieties of sweet corn. Their efforts documented genetic changes in main genes in the amylose storage

pathway that reduces the amount stored as amylopectin and increases the amounts of amylose stored. These genetic changes give maize endosperm greater ability to absorb protein and fat and the ability to paste and resist sheer stress. In effect, the documented genetic changes made the starchy endosperm more malleable for making tamales and tortillas. Gene sequence comparisons between maize and Zea mays ssp parviglumis, like those with c1 [22], tb1 [51], and glb1 [24], indicate a significant bottleneck is associated with this difference—a threefold to sevenfold reduction in nucleotide diversity in the maize sequences can be attributed to stringent selection. No estimates of the size of the bottleneck or its duration were made. Doebley [50] succeeded in identifying and characterizing the gene that freed the grain from the teosinte fruitcase. This gene is also responsible for the loss of lignification and reduced silica deposition in the glume and cupule of the maize cob. Wang and colleagues [50] identify the difference between maize and teosinte as a single nucleotide polymorphism resulting in a single amino acid difference in the first exon of Tga1. In contrast to other known genetic differences between maize and teosinte, this mutation appears to be a novelty, with no similar variation in Z. mays ssp. parviglumis. Statistical comparisons of nucleotide diversity between maize and Z. mays ssp. parviglumis indicate the maize allele has significantly less diversity than the teosinte allele, which again documents (in the promoter and first exon) a genetic bottleneck. The size and duration of the bottleneck is shown to vary with selection intensity. The intensity of selection appears to average about 0.04, with the estimated time since fixation ranging from about 7000 to 12,000 generations (Table 2-2). Wright and colleague [53] also reaffirmed this domestication bottleneck using 774 single nucleotide polymorphisms in 14 U.S. inbred lines and 16 inbred populations of Z. mays ssp. parviglumis. Wright and colleagues document significant effect of human selection on at least 30 of the 774 assayed sites implicating that a large number and variety of genes were affected by human selection during the bottleneck that created maize. Coalescent simulations, such as those performed in previous work [18], depend on the assumption that the domestication bottleneck lasted for a maximum of 2800 years (see Table 2-1). The resulting estimate of the genetic bottleneck is about 3500 plants or about TABLE 2-2 Estimated Divergence Times between Zea mays and Z. m. ssp. parviglumis or Time to Fixation of Maize Allele in Domesticated Populations Gene c1

Divergence time (years BP)

Reference

12,650

[13, 22]

Tgal

5000–15,000

[50]

Microsatellites

5689–13,093

[29]

Maize in the Americas

10% of the teosinte population estimated to be in existence today. Estimates of genetic bottlenecks and their duration vary slightly depending on the assumptions used. Wright and colleagues [53] have depended on an estimate provided by Hugh Iltis in 1983 for maize’s domestication. His estimate was based on limited knowledge about the maize from Tehuacan at the time. Those few estimates that have attempted to independently verify when domestication was initiated push the date back even further.

Archaeological-Macrobotanical-Evidence of Teosinte Domestication and Maize Agriculture Early evidence for human domestication of teosinte was recovered from a small ash lens between zones A and B1 at

15

Guila Naquitz in the Mexican state of Oaxaca. A date on charcoal fragments from Zone B1 yielded a date of about 5800 BC [36]. Two noncarbonized cobs yielded AMS dates that have an average sample age of 4386 BC. The rachis of all three specimens is strongly indurate, rigid, and has a glossy, mottled sheen that closely resembles that of teosinte fruitcases. Two of the specimens (Figure 2-2) have two rows of grain like the teosinte female inflorescence; the third had four rows of grain. This subtle difference—two versus four rows of grain—is one of few vital characteristics that distinguish maize and teosinte. The size of the grain is not significantly different from that of the earliest maize from San Marcos Cave in the Tehuacan Valley [4, 5], although the inflorescences from San Marcos do not have the same cupule shape or mottled rachis sheen seen in the Guila Naquitz specimens. The San Marcos specimens are also significantly later—approximately 700 years, the earliest dating to 3443 + 38 BC. The earliest cobs from San Marcos are contempo-

FIGURE 2-2 Archaeological evidence of early maize evolution from Mesoamerican sites. From left to right: Carbonized teosinte fruitcase fragment from Zohapilco. Modern fruitcases from Zea mays ssp. parviglumis. Teosinte cob fragments from Guila Naquitz C9. Distichous four-rowed cob fragment from D10. Cob from San Marcos Cave 3–5 Zone F. Scale in millimeters. (Courtesy of Bruce Benz) See color insert.

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B. F. Benz

raneous with the earliest at Coxcatlan (Benz, unpublished data, [45]). Early specimens from San Marcos are typical of maize with one significant exception: A significant number of specimens (ca. >5%) are distichous and four-rowed like the specimen from unit D10 [3] at Guila Naquitz. Intense selection documented by high evolutionary rates of morphological change in the maize rachis indicates increasing human dependence on maize in Tehuacan during the latter half of the fourth millennium BC [6, 7]. Estimates of genetic bottlenecks for the earliest transition in Tehuacan are based on the calculation of evolutionary rates. The earliest estimates of bottleneck size vary from 29 to 270 individuals. These estimates are based on a well dated transition that measured 185 years and coincide with the highest overall rates of change. Yet, if we assume that abundance of these remains of early maize from San Marcos accurately reflects their importance, one is led to believe that even though fully domesticated and subject to intense selection, maize was of limited importance in the human diet at this time. If maize was of limited value, the rapid rates of morphological change might seem counterintuitive. That humans would have had such an evolutionary effect on a species so completely dependent on them for survival—requiring protection from marauding macaws and other seed eating birds, deer, coati, and multiple species of rodents—as well as reproduction, is suggested by the aforementioned genetic evidence for either narrow and short-lived or larger and longer-lived bottlenecks. Seed stores set aside for the next years’ plantings were likely marked by occasional seed loss due to seed predators while stored or when they were first planted. Cultivators take their greatest risk when replanting gathered stores of seed because this seed, once domesticated, becomes relatively defenseless; and hence it might be better used by feeding the family or stored until later when protection can be afforded the germinating grains. Loss of stored seed is still relatively common among dry land farmers today. The less effort expended in protecting planted seed, the greater the probability the domesticate population will experience narrow and perhaps repeated short-term bottlenecks. Absent human protection, the more likely morphological variation will appear to be nondirectional because seed predation would be expected to focus and eliminate the traits that are advantageous to humans. On the other hand, evidence for strong directional selection would suggest that cultivators are making the effort to foster the development of certain desirable characteristics among the range of possible phenotypes that achieve reproductive maturity. Directional selection documented at San Marcos and Coxcatlan would be likely to achieve the rapid rate of change at the estimated small population sizes [5, 7]. Once maize appears in the rock shelters of Tehuacan, its cobs tend to increase in abundance and size until Spanish contact (see Chapter 5). Shortly after maize first appears in

Tehuacan, it also appears on the Pacific coast of Chiapas (see Chapter 4).

Pollen Evidence for Use of Zea and Climate Change and Phytoliths Document Neotropical Plant Domestication Evidence that climate changed significantly in Mesoamerica during the Paleoindian and Archaic periods is varied. Flannery [19] documents a faunal change during the Early Ajuereado phase in Tehuacan (40% decorated phytoliths) somewhere in the 5800 to 4200 BC time frame. Zea phytoliths continue up through the stratigraphic sequence to 2920 BC [38]. In summary, the microfossil evidence suggests that Zea occurred well outside the current geographical range of its two closest wild relatives Z. mays ssp. parviglumis and Z. mays ssp. mexicana before evidence documenting maize’s domestication. The pollen grains attributed to teosinte identified in at least three sites in present-day Mexico—Guila Naquitz, San Andres, and Zohapilco—before the first domesticated teosinte cobs appear in Guila Naquitz is compelling. It is intriguing to imagine how and why teosinte might have been dispersed and manipulated to have been so widely distributed so early and yet leave so little evidence of use. Skeptics will argue that perhaps movement of pollen or phytoliths through the profile might displace the evidence by as much as 10 centimeters and that such displacement explains the early geographically disjunct sites [43]. But can such an argument explain all the early occurrence of pollen in Mexico and South America?

JUXTAPOSING THE ARCHAEOLOGICAL AND GENETIC EVIDENCE FOR EARLY MAIZE I have reviewed the genetic evidence that specifically addresses mechanisms and timing of teosinte domestication.

Genetic evidence argues that humans domesticated teosinte, through a short and perhaps repeated, narrow genetic bottleneck or a long protracted bottleneck. Some of this genetic evidence suggests the duration of the bottleneck could have been as short as 300 years. Results of evolutionary rate studies based on macrobotanical evidence indicate focused selection did occur at least once over a short period of time (∼200 years) that could have occurred with a population of ca. 200 plants. Thus there appears to be a certain degree of agreement that a small short-lived bottleneck may be responsible for the genetic polymorphisms in neutral gene sequences, in gene sequences that reflect strong selection and in quantitative variation of archaeological maize cobs from Tehuacan. But what about timing? When did humans first manipulate teosinte to the extent that a founder population gave rise to speciation? The genetic estimates have large confidence intervals (see Table 2-2), though most coincide with an average date around 10,000 to 11,000 years ago. Abundant archaeological evidence on this point is still lacking because all of the pollen and phytoliths data describe few grains or silica bodies when they first appear. Zea pollen and phytoliths suggest that teosinte may have been widely dispersed, perhaps as early as 6500 to 7000 years ago. This is a significant discrepancy from estimates based on genetic evidence, but the discrepancy is that the pollen and phytolith evidence is too young. Returning to a point made previously and elsewhere [2], the antiquity of teosinte domestication will be most accurately and precisely determined by archaeologists. Other methods of estimating when human behaviors touched off the cascade of events leading to maize can never be accurately calculated simply because they are rife with assumptions about demographics, selection intensities, and the number of appropriate genes or nucleotides. But if archaeology is the most appropriate method of making this determination, then why is there a discrepancy? The genetic estimates, which are vague and dependent on assumptions that compromise their accuracy, are nevertheless internally consistent. The estimates of bottleneck size and duration with a variety of neutral gene sequences and estimates of generations separating two gene sequences with fixed differences are corroborated with quantitative estimates based on archaeological material. Each lends credence to the other. If the genetic estimates are consistent, then the problem resides in the archaeological camp, the discipline most capable of making the most precise and accurate determination. Archaeologists have focused their efforts on identifying where and when maize was domesticated in only a few areas of Mesoamerica to answer this question. Many proposals have been tendered to reexamine these areas but have been rejected on the basis that Flannery [19], MacNeish [27], or others could not possibly have missed something. More importantly, the areas of Mesoamerica where the

Maize in the Americas

Archaic or Paleoindian periods have been well studied are not within the current geographic range of maize’s closest wild relative. We need new enthusiasm and tenacity to conduct the systematic archaeological work in this region. And this work needs to be carried out before grazing and deforestation take their toll on the few populations that remain so that appropriate estimates of yield and harvesting efficiency can be carried out. The time to address the problem of when teosinte fell within the sights of early Mesoamericans is now. It is a great time to be interested in the origin and evolution of maize.

Acknowledgments This work was supported by NSF 91490. J. Staller critiqued an earlier version though it should not be mistaken for an endorsement of its contents, I am nevertheless grateful to him for calling my attention to my uncritical reading of some of the published literature cited herein.

References Cited 1. M. Bellon, S. Brush. (1994). Keepers of the maize in Chiapas. Economic Botany, 48, 196–200. 2. B. Benz. (1999). Reconstructing the racial phylogeny of Mexican maize: where do we stand? In: S. Johnannssen, C. A. Hastort (Eds.), Corn and culture in the prehistoric New World. Boulder, CO: Westview Press. pp. 157–180. 3. B. Benz. (1999). On the origin, evolution and dispersal of maize. In M. Blake, Development of agriculture and emergence of formative civilizations in Pacific Central and South America. The prehistory of the Pacific Basin. Seattle: WSU Press. pp. 25–38. 4. B. Benz. (2001). Archaeological evidence of teosinte domestication from Guilá Naquitz, Oaxaca. Proceedings of the National Academy of the Sciences of the United States of America, 98, 2104–2106. 5. B. Benz. (In press). Evidencia arqueológica sobre la evolución del maíz. In: A. Casas, B. Rendon, (coords.), Procesos de evolución de plantas bajo domesticación en Mesoamérica. 6. B. Benz, H. H. Iltis. (1990). Studies in archaeological maize I: The “wild” maize from San Marcos cave reexamined. American Antiquity, 55, 500–511. 7. B. Benz, A. Long. (2000). Early evolution of maize in the Tehuacan Valley, Mexico. Current Anthropology, 41, 459–465. 8. W. Bray, B. Herrera, M. Schrimpff, P. Botero, J. Monslave. (1987). The ancient agricultural landscape of Calima, Colombia. In: W. Denevan, K. Mathewson, G. Knapp, (Eds.), Pre-hispanic agricultural fields in the Andean region. Oxford, UK: British Archaeological Reports International Series. pp. 443–481. 9. E. Buckler, D. Pearsall, T. Holtsford. (1997). The impact of early Holocene climate and plant ecology on Central Mexican Archaic subsistence. Current Anthropology, 39, 152–163. 10. M. Bush, D. Piperno, P. Colinvaux. (1989). A 6000 year history of Amazonian maize cultivation. Nature, 349, 303–305. 11. T. Dillehay, P. Netherly, J. Rossen. (1989). Middle Preceramic pubic and residential sites on the forested slope of the western Andes, Northern Peru. American Antiquity, 54, 73–79. 12. T. Dillehay, J. Rossen, T. Neatherly. (1997). The Nanchoc tradition: The beginning of Andean civilization. American Scientist, 85, 46–55. 13. J. Doebley. (1990). Molecular evidence and the evolution of maize. Economic Botany, 44(3), 6–27.

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14. J. Doebley. (2004). The genetics of maize evolution. Annu Rev Genet, 38, 37–59. 15. J. Doebley, A. Stec. (1991). Genetic analysis of the morphological differences between maize and teosinte. Genetics, 129, 285–295. 16. J. Doebley, A. Stec. (1993). Inheritance of the morphological differences between maize and teosinte: Comparison of results for two F2 populations. Genetics, 134, 559–570. 17. J. Doebley, A. Stec, L. Hubbard. (1997). The evolution of apical dominance in maize. Nature, 386, 485–488. 18. R. L. Eyre-Walker, J. Gaut, H. Hilton, D. L. Feldman, B. S. Gaut. (1998). Investigating the bottleneck leading to the domestication of maize. Proceedings of the National Academy of the Sciences of the United States of America, 95, 4441–4446. 19. K. Flannery. (1967). The vertebrate fauna and hunting patterns. In: D. Byers (Ed.), The prehistory of the Tehuacan Valley Vol. 1. Austin: The University of Texas Press. 20. P. Goloubinoff, S. Paabo, A. Wilson. (1993). Evolution of maize inferred from sequence diversity of an adh2 gene segment from archaeological maize. Proceedings of the National Academy of the Sciences of the United States of America, 90, 1997–2001. 21. M. Goman, R. Byrne. (1998). A 5000 year record of agriculture and tropical forest clearance in the Tuxtlas Veracruz, Mexico. The Holocene, 8, 83–89. 22. M. Hanson, B. Gaut, A. Stec, S. Fuerstenberg, M. Goodman, E. Coe, J. Doebley. (1996). Evolution of anthocyanin biosynthesis in maize kernels: the role of regulatory and enzymatic loci. Genetics, 143, 1395–1407. 23. J. Harlan, J. DeWet, E. Price. (1973). Comparative evolution of cereals. Evolution, 22, 311–325. 24. H. Hilton, B. Gaut. (1998). Speciation and domestication in maize and its wild relatives: Evidence from the Globulin-1 gene. Genetics, 150, 863–872. 25. V. Jaenicke-Deprés, E. Buckler, B. Smith, M. Gilbert, A. Cooper, J. Doebley, S. Pääbo. (2003).Early allelic selection in maize as revealed by ancient DNA. Science, 302, 1206–1208. 26. P. C. Mangelsdorf. (1974). Corn: Its origin, evolution and improvement. Cambridge, MA: Belknap Press of the Harvard University Press. 27. R. MacNeish. (1967). A summary of subsistence. In: D. Byers (Ed.), The prehistory of the Tehuacan Valley. Vol 1. Austin: University of Texas Press. pp. 290–309 28. B. McClintock, T. A. Kato Y., A. Blumenschein. (1981). Chromosome constitution of races of maize (Constitución chromosoma de razas de maíz). Chapingo, Mexico: Colegio de Postgraduados. 29. Y. Matsuoka, Y. Vigouroux, M. Goodman, J. Sanchez G., E. Buckler, J. Doebley, A single domestication for maize shown by multilocus microsatellite genotyping. Proceedings of the National Academy of the Sciences of the United States of America, 99, 8060–8064. 30. S. Metcalfe, F. Street-Peirott, R. Brown, P. Hales, R. Perrott, F. Steininger. (1989). Late Holocene human impact on lake basins in central Mexico. Geoarchaeology, 4, 119–141. 31. S. Monsalve. (1985). A pollen core from the Hacienda Lusitania. ProCalima, 4, 40–44. 32. S. Mora, L. Herrera, I. Cavelier, C. Rodriguez. (1991). Cultivars, anthropic soils and stability. University of Pittsburgh Latin American Report No. 2. Pittsburgh, PA: Department of Anthropology, University of Pittsburgh. 33. C. Niederberger. (1976). Zohapilco: Cinco millenios de ocupacion humana en un sitio lace de la cuenca de Mexico. Coleccion Cientifica 30. Mexico, D.F.: INAH, 1976. 34. C. Niederberger. (1979). Early sedentary economy in the basin of Mexico. Science, 203, 131–142. 35. S. O’Hara, A. Street-Perrott, T. Burt. (1993). Accelerated soil erosion around a Mexican highland lake caused by prehispanic agriculture. Nature, 362, 48–51.

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36. D. Piperno, K. Flannery. (2001). The earliest archaeological maize (Zea mays L.) from Mesoamerica: New accelerator mass spectrometer dates and their implications. Proceedings of the National Academy of the Sciences of the United States of America, 98, 2101–2103. 37. D. Piperno, M. Bush, P. Colinvaux. (1990). Paleoenvironments and human occupation in late Glacail Panama. Quaternary Research, 33, 108–116. 38. D. Piperno, D. Pearsall. (1998). The origins of agriculture in the Lowland Neotropics. San Diego: Academic Press. 39. H. Perales, B. Benz, S. Brush. (2005). Maize diversity and ethnolinguistic diversity in Chiapas, Mexico. Proceedings of the National Academy of the Sciences of the United States of America, 102, 949–954. 40. K. Pope, M. Pohl, J. Jones, D. Lentz, C. von Nagy, F.Vega, I. Quitmyer. (2001). Origin and environmental setting of ancient agriculture in the lowlands of Mesoamerica. Science, 292, 1370–1373. 41. J. Schoenwetter. (1974). Pollen records of Guila Naquitz Cave. American Antiquity, 39, 292–303. 42. J. Shoenwetter, L. Smith. (1986). Pollen analysis of the Oaxacan Preceramic. In: K. Flannery (Ed.), Guila Naquitz. Orlando, FL: Academic Press. 43. A. Sluyter. (1997). Regional, Holocene records of the human dimension of global change: sea level and land use change in prehistoric Mexico. Global and Planetary Change, 14, 127–146. 44. B. Smith. (2005). Reassessing Coxcatlan Cave and the early history of domesticated plants in Mesoamerica. Proceedings of the National Academy of the Sciences of the United States of America, 102, 9438–9444. 45. M. Stuiver, P. Reimer. (1993). Extended 14C database and revised CALIB radiocarbon calibration program. Radiocarbon, 35, 215–230.

46. M. Tenaillon, M. Sawkins, A. Long, R. Gaut, J. Doebley, B. Gaut. (2001). Patterns of DNA sequence polymorphism along chromosome 1 of maize (Zea mays ssp. mays). Proceedings of the National Academy of the Sciences of the United States of America, 98, 9161–9166. 47. M. Tenaillon, M. Sawkins, L. Anderson, J. Doebley, S. Stack, B. Gaut. (2002). Patterns of diversity and recombination along chromosome 1 of maize (Zea mays ssp. mays L.). Genetics, 162, 1401–1413. 48. M. Tenaillon, J. U’Ren, O. Tenaillon, B. Gaut. (2004). Selection versus demography: A multilocus investigation of the domestication process in maize. Molecular Biology and Evolution, 21(7), 1214–1225. 49. S. Whitt, L. Wilson, M. Tenaillon, B. Gaut, E. Buckler. (2002). Genetic diversity and selection in the maize starch pathway. Proceedings of the National Academy of the Sciences of the United States of America, 99, 2959–2962. 50. H. Wang, T. Nussbaum-Wagler, B. Li, Q. Zhao, Y. Vigouroux, M. Faller, K. Bomblies, L. Lukens, J Doebley. (2005). The origin of the naked grains of maize. Nature, 436, 714–719. 51. R. Wang, A. Stec, J. Hey, L. Lukens, J. Doebley. (1999). The limits of selection during maize domestication. Nature, 398, 236–239. 52. S. White, J. Doebley. (1999). The molecular evolution of terminal ear1, a regulatory gene in the genus Zea. Genetics, 153, 1455–1462. 53. S. Wright, I. Vroh Bi, S. Schroeder, M.Yamasaki, J. Doebley, M. McMullen, B. Gaut. (2005). The effects of artificial selection on the maize genome. Science, 308, 1310–1314. 54. E. Steig, E (1999). Mid-Holocene climate change. Science, 386, 1485–1487. 55. D. Rue. (1987). Early agriculture and early Postclassic Maya occupation in western Honduras. Nature, 326, 285–286.

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3 Origin of Polystichy in Maize HUGH H. ILTIS Department of Botany, University of Wisconsin–Madison, Madison, Wisconsin

Abstract 22 Introduction: The Origin of Maize 23 The Maizoid Eve—An Emphatic Restatement 27 First for Sugar, Then for Grain: Reflections on Corn Domestication Chronology 28 The Cupulate Fruitcase and the Ear Cluster: Adaptive Marvels of Coordinated Sequential Maturation 32 The Origin of Polystichy in Maize 33 The Shank and Its Husks—The Key to Maize Ear Polystichy 39 From Teosinte Distichy to Maizoid Polystichy: Or How to Study Husk Phyllotaxy in Nine Easy Steps 45 S. G. Stephens and the Shank Condensation Theory—Sharp-Eyed, Unsung, Uncited, and Unequivocally Correct 49 Postscript 50

Distichy, Distichous Longitudinal arrangement of leaves, husks, or grains in two rows or ranks, on opposing sides of a branch, or a single row of CFCs in the teosinte ear, but facing alternately left and right. Phyllotaxy The arrangement of leaves, husks, grains, and so on, on the stem axis (e.g., alternate—distichous, opposite—distichous, decussate, spiral, or whorled husks in the shank grading from the first to the last). Polystichous Arrangement when leaves, grains, and so on, are born in more than two vertical rows or double rows (ranks) such as grains on the maize ear. Proto-maize Ears of Zea morphologically intermediate between a distichous, two-ranked teosinte and a polystichous, four-ranked ear of maize. Spikelet The basic flowering structure in grasses, in Zea, either male or female, but theoretically always in pairs. A pair comprises a sessile spikelet (ss) that is fertile in both the teosinte and maize ear and one pedicellate spikelet (ps), which is suppressed in the teosinte ear but not in the tassel and became reactivated in the maize ear. Teosinte The six wild species or subspecies of Zea. Here mostly referring to the annual subspecies parviglumis (rarely to subspecies mexicana [Mexican Plateau] or subspecies huehuetenangensis [Guatemala]), most native to Mexico, but one reaching Nicaragua. Tga 1 Teosinte glume architecture 1, a one-time true gene mutation. The only one in the evolution of maize, identified in maize and transferred genetically into teosinte, where it is unknown in the wild; it opened up the cupule, softened the glume, and made the grain accessible to harvest, and started the domestication of maize. Unconscious mass selection Automatic random selection of desired attributes by mass harvest of common standing minor variations.

Glossary Apical dominance Human selection for concentration of nutrients from many small ears in teosinte to one terminal, easy to harvest maize ear (e.g., an analogous example, the monocephalic sunflower). Compression, Condensation Shortening of internodes in shank or ear, leading often to fusion of nodes and increase of husks/visible node (cf p. 42). Conscious selection Deliberate picking of individual plants with desirable characteristics and propagating them (e.g., for higher yield, nonfragmenting ears, naked grains, etc.). (See unconscious mass selection.) Cupulate fruitcase (CFC) The grain dispersal unit of teosinte, in effect, the sessile grain imprisoned permanently by the hard, hollowed-out cupule and permanently closed off by its own hard outer glume, which make the grain inaccessible to harvest.

Histories of Maize

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Copyright © 2006 by Academic Press. All rights of reproduction in any form reserved.

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ABSTRACT The teosinte mutation hunt of late Fall 1971, and its two successors (1972–1973), organized by the geneticist George W. Beadle [7, 8, 92], despite yielding not one single, searched-for, soft-glumed, or “threshable” mutant among almost four million teosinte cupulate fruitcases (CFCs) harvested and eventually examined individually in Chicago by Beadle himself, were far from exercises in futility. The hunts proved not only the deep genetic canalization of the CFCs, but also the superrarity of Tga (Teosinte glume architecture), a one-time, minor, atavistic, yet key gene mutation, genetically recovered from contemporary maize and reinserted into teosinte. This mutation “opened” the CFCs, softened their outer glume, and exposed their grain, which allowed for the first time both human grain harvest leading to domestication and reactivation of the pedicellate spikelet leading to selection for increased apical dominance. Unknown in the wild, the astronomical rarity of Tga suggests its fortuitous discovery in a single “Maizoid Eve” or her immediate progeny within a teosinte stand already of interest for its sugary pith to a population of hunter– gatherers, who were thus psychologically fully prepared to pay attention to this Teo Centli (“God’s dry ear of maize,” in Nahuatl). By this single, modest genetic change, with such enormous morphological consequences, which by force of logic must have been ancestral to all the maize in the world, maize domestication differed radically from that of Old World grains, based as these were on a paradigm of unconscious mass selection by mass harvest of the many common standing variations. Incorporation of Tga under human protection proceeded in a predictable sequence of domestication morphologies, constrained by the narrow realities of teosinte architecture (e.g., sequential ear maturations) and channeled inexorably by mostly ± human conscious selection for apical dominance through increased condensation, to find its ultimate expression in the easily harvestable, abundantly yielding, terminal polystichous ear of maize. This, known as the Orthodox Teosinte Hypothesis (OTH) [52], is now generally accepted (see Box 3-1, this page). Selfing and backcrossing to wild-type teosinte quickly assimilated Tga and, thus, with continuous and increasing human protection, proto-maize escaped this narrowest of domestication bottlenecks. With time, ± conscious selection for increased condensation, loss of abscission layers, number of alicoles, longitudinal vascularization, and reactivation of the pedicellate spikelets from frequent, naturally occurring, standing variation as reflected in the earliest archaeological proto-maize ears, allows us to view the probable sequence of events. G. N. Collins’ ideas [18] on decussation of yoked alicoles illustrated correctly the maize ear’s symmetry; yet, like subsequent ideas of “second bifurca-

Maize as a Super Domesticate of Teosinte Maize is domesticated teosinte (Zea mays ssp. parviglumis), differing not at all in any of its basic vegetative, floral, or genetic attributes. All the unique peculiarities of maize are concentrated in the structure of the female inflorescence, the maize ear, and all can be easily interpreted as the result of human selection for human needs for more food, whether it be for greater quantity or for greater, more efficient harvestability. Thus, compared with wild Teosinte, the increase in the volume of harvest subunits, namely in grain size, in grain number through activation of aborted spikelets and aborted florets, in row number and in ear length, were all selected for by primitive man to produce more food. The decrease in the number of primary harvest units (the female inflorescences) to one or two giant, apically dominant, terminal inflorescences per plant, the coordinated function of protecting the many, now suppressed, lateral ears, and the change from a fragmenting, disarticulating rachis (ear axis) and rachilla to one that is shatterproof, were all selected for by primitive man to increase the ease and efficiency of harvesting. In addition, the reinforcement in the maize plant of Teosinte’s annual habit and of a single, gigantic stem are likewise due to human selection. The resulting cultigen is easily grown, easily harvestable and abundantly yielding. Written in 1970 [52], first published in mimeograph form at the University of Wisconsin, 1971, and later reprinted by Major M. Goodman in 1988 [44, p. 205] as an example of the “Descent from Teosinte” hypothesis, and here revised by using “maize” instead of corn, and “ear” instead of cob, and the correct Latin binomial.

tions” [80] to explain polystichy, it left too many unanswered questions because of an exclusive focus on the ear. The priority given by Iltis [54, 55] to sexual transmutation of the primary tassel into a maize ear, was largely mistaken and unnecessary. But even today [57], it is still a useful explanation of homeotic sexual conversions or transmutations of secondary tassels in the upper branches into ears (cf. legend to Figure 3-5) and, eventually, of the primary branch tassels as well, the latter phenomena related to automatic, Quantitative Trait Locus (QTL) tb1-induced, developmentally restraining effects on branching by environmental competition, as in any weedy, labile annual, whether a teosinte or a ragweed (Figure 3-3). Lastly, S. G. Stephens’ [79] Shank Polystichy Theory (SPT), as I shall call it, now finally rehabilitated, is based on maize shank morphology, and the fact that, during its ontogeny, its husks change from an uncondensed, distichousalternate, horizontal teosintoid phyllotaxy at the shank’s base, by way of condensation-caused, spiral-gyrate “twist-

Origin of Polystichy in Maize

ing” compression and fusion of nodes, to a congested, whorled maizoid phyllotaxy at the shank’s apex where, when seamlessly transferred into the reproductive mode, it initiates polystichy in the maize ear.

INTRODUCTION: THE ORIGIN OF MAIZE The origin of maize, the still somewhat contentious story of the domestication of a Mexican tall grass called teosinte by local, Pre-Columbian agriculturalists, has occupied botanists, geneticists, anthropologists, and archaeologists for more than 100 years [5, 77]. Today, geneticists universally accept the OTH (Figure 3-9, Box 3-1) that maize is solely derived from a teosinte, more specifically from a population of Balsas Teosinte, as described in H. Garrison Wilkes’ [91] monograph and sci-

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entifically classified as Zea mays L. ssp. parviglumis Iltis and Doebley [23, 60], a native of the upper, S-facing slopes of Mexico’s Meseta Central, where this often abundant grass with multiple minute ears produces prolific, easily harvestable “grains.” Yet, paradoxically, these grains are inaccessible, hence unusable for food, imprisoned permanently as they are inside hard, woody, silica-impregnated CFCs (Figure 3-8A, B). Paradoxically, these highly polished “seeds,” superbly adapted for internal animal dispersal or by gravity, are, despite being indestructible, totally unknown from the early archaeological record, except for two CFCs from near Mexico City noted by J. L. Gonzalez and L. Lorenzo in 1970 [65] of Z. m. subspecies mexicana (Schrader) Iltis, an unlikely ancestor of the Mexican Plateau, and one or two fragments from elsewhere, none of which point to either human use or agricultural activity [13, p. 91; 54, p. 93, footnote 19, but see 92, p. 220]. So what induced domestication?

FIGURE 3-1A Tropical deciduous forests and savannas in Guerrero, southern Mexico; Landscape 7 kilometers west of Teloloapan at km 70–71 on Mexico’s Rt. 51 from Iguala to Arcelia during the beginning of the dry season, where extensive stands of ripe Balsas Teosinte (Zea m. parviglumis) among scattered trees of Bursera, Ipomea, and Acacia cover hillsides and arroyos. This was one of the first stops of the 1971 teosinte mutation hunt (TMH), organized by George Beadle [7, 8]. Photo H. H. Iltis © 2005. Also appears in color insert.

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FIGURE 3-1B Closeup in the teosinte stand, with T. S. Cochrane (left, also in 3-1A), curator of the University of Wisconsin Herbarium, and H. G. Wilkes (right), world authority on teosinte, collecting samples of teosinte fruitcases (CFCs) from each of several hundred plants. Despite the fact that the three TMHs (1971–1973) did not find a single soft-glumed mutant after collecting a total of several million CFCs, the negative results were, in fact, a positive finding, proving the mutant’s extreme rarity and the uniqueness of maize domestication. Photo © H. H. Iltis, November 20, 1971. Also appears in color insert. Beadle knew well what he wanted us to look for, but also what to expect, for he wrote us TMH participants in June, 1971: “Do not be discouraged if you do not find exciting mutants in the first 10,000 plants—or even in the entire week. If we find a single, soft-fruitcase mutant during the entire week that will be a great achievement.”

Until recently, most authors still followed the standard Eurasian model of grain domestication by mass harvest of wild plants leading to automatic, unconscious mass selection of the common standing variation [46, 54, but see 22]. This scenario left us wanting and the analogy faulty. Even Beadle’s [6, 7, 8] “4 or 5 required mutations” is a model infected with Old World ideas of crop domestication. For now, in fact, it seems probable that only a one-time, modest yet crucial gene mutation, the superrare, unique yet atavistic Teosinte glume architecture 1 or simply Tga 1 (Figures 3-7D, 3-8C–E ), discovered in maize by John F. Doebley and his team, set the stage for all the evolutionary drama that followed [22, 24, 26, 27, 57, 84]. Despite Beadle and his mutation hunters’ best efforts, it remains to this day undiscovered in the wild.

Plants of the genus Zea, whether teosinte or maize, are summer-rain germinating, fall-maturing, short-day (shortening-day, as Iltis [55] called them) tropical climate giants, unisexual and outcrossing. When they are well grown, they have enormous sugar-storage capabilities that, in their lifecycle, differ dramatically from the slender and ephemeral, perfect flowered and selfed, winter-rain germinating, and late spring-maturing, long-day (lengtheningday) cereals of the Old World’s Near Eastern temperate cradles of grain domestication. As is well known, before mechanized agriculture, maize plants, like all New World crops, such as squash or beans, had to be individually handplanted, becared, consciously selected, and harvested, with Old World type mass sowing, mass harvesting, and unconscious mass selection an imaginative dream. The first one

Origin of Polystichy in Maize

led to gardening and horticulture, the other, preadapted to mass sowing in dense stands, to agriculture. We do know a great deal about the evolution of the maize ear, that unique structure, but exactly how, and in what sequence, the CFCs, with their single grain inside, coalesced into a corn ear with naked, harvestable grains, is still somewhat problematic, especially in its earliest agricultural beginnings, and so it seems is the transition to polystichy. Nevertheless, we may well apply Stephen J. Gould’s apt aphorismic observation from his 2002 masterpiece The Structure of Evolutionary Theory [45] as the leitmotiv to the origin and domestication of maize: “Architectural constraints limit adaptive scope and channel evolutionary patterns” [28, p. 1683]—toward ever-greater apical dominance with ever-greater condensation in ever-fewer ears, eventually culminating in the polystichous, apically dominant, terminal ears of maize. Understanding the basic bilateral dorsiventrality [15] of the Zea plant is the key to understanding its domestication. Recently, I made some unorthodox suggestions [57, pp. 29–36], citing the total lack of any agriculturally significant early archaeological remains of teosinte and the astronomical rarity of any mutation affecting changes in the morphology of the teosinte CFC, that the initial maize domestication by Mexican hunter–gatherers 7000 to 8000 years ago must have involved uses of teosinte other than for grain: 1. Teosinte stands, dense and locally abundant as they often are, were tended originally not for grain, but for sugary pith or young ears as vegetable (e.g., pith to chew on, corn beer fermentation, etc.) (Figure 3-2A, B) [19, 57, 78, 89]. 2. Only one, single, superrare crucial gene mutation, Tga 1 (Figure 3-7D, 3-8C, D), started grain domestication. It “shallowed,” shortened, and opened the cupule, softened the outer glume, projected outward a weakly attached grain, and so finally allowed human harvesting and use. In fact, it appears to have been the only gene mutation in the whole story, and a minor one at that [22, p. 55, 26, 27, 84]. 3. As a consequence, there was no possibility for gradual, unconscious selection (as described by Daniel Zohary [93]) for bigger or better grains before Tga appeared on the scene, as has been claimed by some [17, 30]. 4. The overall theme of corn domestication was increased apical dominance made possible by the hierarchically staggered, sequential maturation system of the teosinte cymose ear clusters (rhiphidia), inherent architectural constraints that, first described by Julian Camara-Hernandez and S. Gambino [16], channeled all subsequent morphological changes in one predictable direction (Figure 3-6) [16, 57]. 5. The extreme, astronomic rarity of Tga, the key gene mutation (one in four million, or much rarer), lethal in nature

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because of vertebrate and insect predation of the now unprotected grain, known only from maize but genetically transferred to teosinte [22, 27] and still unknown in the wild, leads to the inescapable conclusion that its fortuitous accidental discovery must have occurred within a teosinte population already under human surveillance for uses other than grain, with corn beer being a good candidate [19, 54, 55, 57, 78, 89]. 6. For the same reasons, namely the extreme rarity of the important mutation and the evident disuse of CFCs, the fortuitous, accidental discovery of that mutation was postulated to have occurred initially in a single, mutated “founder plant,” in short, in a Maizoid Eve [57] or her immediate descendants, within a parviglumis population already watched over and used by hunter–gatherers. 7. The proposed geographic location of the original domestication was the southern escarpment of the Mexican Plateau, the Meseta Central, high above and north of the Rio Balsas at circa 900–1400 meters, somewhere between Teloloapan, Valle de Bravo, and Arcelia. This is not only because Beadle’s 1971 teosinte mutation hunters, with the western group under the expert leadership in the field of Garrison Wilkes [91, 92], found many large, vigorous, dense local populations of parviglumis there, but also, coincidentally, because of the extremely high local floristic endemism for which that region is justly famous and of which parviglumis is a part, a biodiversity “hot spot” of endemic genera and species that could only have developed in situ over many millions of years. It should be, thus, of some interest to people interested in the origin of maize, and certainly a personal satisfaction to me, that many of these ideas first proposed in 2000 [57, 59], although on the basis of circumstantial, negative evidence of the total absence of teosinte in the older archaeological record, the total absence (or at least extreme rarity) of any significant gene mutations in the millions of CFCs gathered on Beadle’s several teosinte mutation hunts [7, 8], and the ubiquitous presence of vast stands of Balsas teosinte in the mountainous southern escarpment and the superrich local floristic endemism therein, have now been verified in John Doebley’s lab by hard, far-reaching, highly sophisticated molecular microsatellite data, with which no one can argue [22, 33, 69, 84]. These studies are surely milestones in the application of molecular genetics to the solution of ethnobotanical problems. Even though they renamed my Maizoid Eve [57, p. 35], and then forgot to cite it, they came to the same conclusion; namely, that “maize arose from a single domestication event (sic) in southern Mexico about 9000 years ago . . .” with the most primitive, “oldest, surviving maize types [being] those of the Mexican highlands . . .” north of the Central Balsas River drainage on the south facing slopes of the Mexican Plateau [69].

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FIGURE 3-2A Multiple uses of Zea I: Three boys on a Sunday outing with their parents, chewing sweet stems of Zea (either subspecies mays or subspecies mexicana, for both grew here in abundance), southeast of Chalco on the road to Amecameca near the upper edge of the Valley of Mexico. These stems had been prepared for the boys by having the hard rinds of the culms shaved off with a machete. At the time the photo was first published in 1982 the photographer suggested that, for prehistoric hunter–gatherers, green ears or sweet stems of wild Zea were initially of much greater importance as food, even if only as an occasional snack, than were the ripe grains, the latter becoming more important only with the development of the ear of maize [19]. It is notable in this regard that in dry caves near Tehuacán in southern Mexico, ca. 5000-year-old (?) Zea ears were found together with “quids” of chewed up, spit out maize stems. Photo September 30, 1978, © 1982 H. H. Iltis.

(Continued)

There, after George Beadle departed back to Chicago, my fellow mutation hunter Ted S. Cochrane and I, in December of 1971, in this ancient cradle of maize domestication, south of Morelia on the high slopes of the Meseta Central escarpment overlooking the Rio Balsas valley and just south of the little pueblo of Tzitzio, (and on a hint from a young, blackhaired, sharp-eyed, and lively Native American chambermaid at Motel Morelia in the city of that name while watching us make herbarium specimens of teosinte) we discovered several fine stands of our special grass, both truly wild ones on almost vertical rocky slopes and weedy ones in maize fields, where, with tassels and leaves already removed by the local campesinos to feed their cattle, the dried out maize ears were ready for harvest. It may well have been nearby that some eight millenia ago, perhaps even in that same teosinte patch, one then already well-known and

becared by the keen mentality of an unsung, ever-hungry people, this naked-grained mutant made its unexpected appearance, one that surely would not have gone unnoticed for long. In fact, we may imagine that maize domestication may well have begun here with the startled cry in Nahuatl of some bright, strong, young Indian woman or man, a “Xilonen” or a “Cuauhtemoc,” holding a cluster of young, crisp mutated teosinte ears in hand, exclaiming excitedly to a companion, “Look, look what I found—these surely must be teo centli!” All we hope to do here is to select certain topics that help us understand the morphology of teosinte as it evolved into the proto-maize ears from Guila Naquitz cave in Oaxaca by 6250 radiocarbon years BP [10, 74] and piece together a morphologically reasonable, genetically concordant scenario of what nearly two millenia later led to the wonder of

Origin of Polystichy in Maize

27

FIGURE 3-2B The multiple uses of Zea II: House wall made of maize culms (or, less likely, parviglumis teosinte?) at El Crustal, ca. 1000 meters, at km 105, 20 kilometers west of Teloloapan, Guerrero, Mexico, in the heart of parviglumis teosinte tropical deciduous savannas. The enormous, temporary sugar-storage capacity of the young pith inside of these bamboo-like culms, which circumvents the seasonal reduction in photosynthate during the “shortening” days of fall, may have initiated the interest of hunter–gatherers in teosinte [55, 57]. Photo © H. H. Iltis, October 1, 1982.

wonders, the tiny polystichous eight-rowed ears of maize from San Marcos Cave in the Tehuacan Valley [11, 67].

THE MAIZOID EVE—AN EMPHATIC RESTATEMENT A brief exposition, with a correction and reaffirmation of the Maizoid Eve concept is in order, now that it has recently [69] been renamed the “single domestication event” without any reference to its original publication [57]. In all fairness, and to keep the historical record straight, the concept of “the single domestication event” is borrowed from an earlier paper of M. M. Goodman [44], one of the coauthors of the famous 2002 paper by Matsouka and colleagues [69], in which he suggests among three possibilities for maize domestication, a “single evolutionary event involving a pair of plants (or at most a very small population)” [44, p. 213]. (It is hard to resist not wondering why a biblical pair is needed when Adam alone and his rib would suffice.)

The concept of a single mutated plant, a Maizoid Eve, starting the maize domestication is worth considering, because it is based on the unique domestication mutant, Tga 1, the only true gene mutation in the whole story, which, by opening up the CFC, opened up the possibility for human use and domestication [22]. That supposition is based on the extreme rarity of this gene, which, quite unadaptive and destructive in teosinte to the deeply canalized, invariable, specialized, adaptive syndrome that the CFC represents, was not found once among the approximately four million CFCs collected on Beadle’s three mutation hunts, even though finding such a soft-glumed mutant was specifically one of the aims of that grand endeavor. The Tga rarity is so extraordinary that, statistically, it could not have met up with another of its kind in the same place at the same time, except in someone’s unrealistic imagination. (Here, I have to admit to a mistake or omission, or both, in my original discussion [57, p. 35], for I do not know where most of my quoted remarks, cited below, came from. Although Goodman [44] credited a reference that apparently does not exist [was it meant to be 1988 and not 1987?], page 213 is

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H. H. Iltis

cited from the 1988 paper, but none of the cited text came from that paper. My apologies to Dr. Goodman and the reader.) Nevertheless, here is the original quote concerning the Maizoid Eve [57, p. 35]. It was, “only one, large mutated ‘founder plant’ (cf. Goodman 1987, p. 213) . . . producing many fruitcases . . . in short, a maizoid ‘Eve,’ and that . . . extremely small effective population . . . [that evolved from it] facilitated the fixation of mutant alleles, and then, ‘acquired . . . over the centuries, . . . its cytological enzymatic, and morphological variation by a combination of mutations and back crossing to the parental taxon.’ [Goodman, 1987 (sic), p. 213].

It has been pointed out that one single plant could not have given rise to maize because the domestication bottleneck could not have been that small. The theoretical length of the domestication bottleneck in maize evolution is unknown. Quoting Eyre-Walker and colleagues [29], who mention “only 20 individuals . . . in 10 years,” Hilton and Gaut [49] indicate “that the founding population is dependent on the duration of the bottleneck, but that the population could have been quite small. . . . if domestication were completed in 10 years . . . the domesticate could have been based on 10 individuals. . . . Unfortunately, there are no good independent estimates for the true duration of the single domestication event. Furthermore, the coalescent model is a simplistic representation of the domestication process. For example, it cannot establish whether introgression has occurred on a wide scale after domestication” [29]. It is worth noting that one large Tga mutated plant, with about 100 ears and, hence, approximately 1000 mutated fruitcases and 30 million mutation-carrying pollen grains, growing in the middle of a dense ancestral teosinte population recognized and appreciated by a group of hunter– gatherers for generations, could, by both outcrossing to neighboring teosinte plants and selfing, spread the mutation widely even in the first year or two, and if followed by occasional introgression and even the mildest human selection, start the domestication process all by itself.

The Maizoid Eve Concept Is Useful and Should Not Be Rejected Once the mutation occurred and was recognized, it had to be taken under human control, even if weak, within a leeway of only a few generations (years), at least initially to the extent of keeping predators away in the fall. By the time the hypothesized removals from the original site to Oaxaca (Guila Naquitz) and elsewhere, the proto-maize must have been cultivated and mostly free of introgression, provided there was not some wild teosinte nearby. Such removal would have been analogous to biogeographic long-distance dispersal and the consequent effects of isolation on evolu-

tion, with species and even genera evolving from only one single seed introduced onto an oceanic island. A word about hybridization between maize and teosinte is in order. Evidently, such hybridization, although widespread, is sporadic and idiosyncratic, depending perhaps more on local environmental conditions than on genetics. During the 1971 teosinte mutation hunt in Guerrero west of Teleloapan, we found hardly any hybrids, at most two or three, during a week of collecting parviglumis; an absence that Garrison Wilkes suggested (personal communication) was caused by differential pollen-shedding seasons between the wild and cultivated plants. On the other hand, of the teosinte populations along the path from El Rodeo (north of Zenzontla) to El Durazno, in the depression separating Jalisco’s Sierra de Manantlan Occidental from Central, in a mosaic of open woods, small maize fields, hedge rows, and pastures along a small stream, two of the major populations did not have any hybrids, but one close to the stream had about 10% F1 hybrid plants (Iltis, unpublished data). Similarly, despite a report suggesting the contrary [33, p. 2251], maize and Zea mays ssp. huehuetenangensis may hybridize readily. In fact, the type collection of that subspecies (Iltis and Lind, G120) [60, pp. 202–203], from just outside of San Antonio Huista on the road to Jacaltenango, was composed of, in addition to many of its isotypes, some 25 or more F1 hybrids that constituted nearly 8% of the population (with their nonfragmenting ears still kept in individual envelopes in the University of Wisconsin Herbarium). In contrast, nearby populations, such as those along the road to Santa Ana Huista, contained no hybrids. There are many other such similar examples.

FIRST FOR SUGAR, THEN FOR GRAIN: REFLECTIONS ON CORN DOMESTICATION CHRONOLOGY The unraveling of the domestication history of the Old World’s cereals during the past century was such an elegant success story that it has tempted ethnobotanists to apply it automatically but unwittingly to that of the New World’s maize. “[O]bviously, the last word has yet to be said about the origin of maize, but I find no reason to suppose that the evolution of maize is radically different from that of any other cereal,” wrote Jack Harlan [46]. Several years earlier, Iltis [52] wrote almost the same words before he knew any better. Similarly, geneticists, before and after Beadle’s [6] classic short paper questioning Paul C. Mangelsdorf and R. G. Reeves’ [68] Tripartite Hypothesis, followed the dogma of the four or five gene mutations required to make a usable primitive maize from teosinte. But maize is not wheat or barley! For the Old World cereals, the main theme was always the domestication of a wild species by the gradual, fortu-

Origin of Polystichy in Maize

itous, unconscious accumulation of useful “gene mutations” (actually now, mostly QTLs from the common standing variation as described by Doebley [22]), with no particular mutation as the starting point. For the same reasons, it is unlikely that these hunter–gatherers went out to look for teosinte mutations, deliberately or unconsciously. And, to compare them with Beadle’s 1971 mutation hunters of some 8000 years later is to base the comparison on a shaky analogy. For them to hunt for mutants of edible cucurbits, legumes, and avocados would be more likely, but for these hunter–gatherers to seek out mutants of a species with useless, hence, unused grains is unlikely, indeed. Thus, our group of mutation-hunting maize evolutionists, who, it was claimed, when looking for that elusive, soft glumed mutation, “toiled together collecting teosinte on the parched hillsides of the Balsas River valley, where perhaps some 8000 years earlier ancient Mexicans also were searching through the same teosinte fields for a plant with a promising mutation. . . .” is a comparison by Doebley [21, p. 490] based, like so many others, on the Old World domestication template. That the highly focused “[Beadle] expedition yielded no natural mutants of teosinte. . . .” with soft glumes is, of course, hardly surprising, considering the odds of finding one that is so incredibly rare. That the ancient Mexican hunter–gatherers would have had any interest in even looking for teosinte mutations (except for their incredibly good fortune much later, after using teosinte for generations, of accidentally finding and recognizing the value of Tga 1 in a field already under surveillance) is even less likely. Teosinte is different from any Old World cereal. Its grains are not useful from the start because they are permanently and unmutably imprisoned in a hard, nonremovable CFC, which is a rigidly invariable, deeply canalized structure that despite being literally indestructible, has never been found in the older archaeology. In fact, the earliest evidence of maize evolution are not CFCs at all, but three, 6250-yearold proto-maize ears from Guila Naquitz Cave near Oaxaca that were distichous, nonfragmenting, and well on their way to becoming maize ears [10, 74]. Thus, the theory was proposed some 25 years ago by Iltis [19, 57] that teosinte was initially used not for grain but for the sugar in its pith or for the crisp, green ears as a vegetable. Many years later, in the early 1990s, a single, superrare gene mutation, (e.g., Teosinte glume architecture 1, or Tga (Figure 3-8C–E) was “discovered,” one that made the grain accessible to harvesting in a population already watched over and recognized as useful by the people [27]. It was a mega-mutation, in terms of its far-reaching morphological effects, that softened the hard outer glume, flattened the cupule, and slanted the now naked grain out of that prison, and by doing so, made it accessible to easy removal, which allowed humans to harvest, use, and domesticate it [84]. In the process, of course, it destroyed the highly adaptive, integrated CFC morphology, and so handed over the

29

cereal’s survival to the hunter–gatherers who discovered it. Because of the rarity of such a mutation (one in four million or rarer), it must have first occurred in a single founder plant, a Maizoid Eve, that as Doebley [22, p. 52] recently noted “behaves like a simple Mendelian locus [and one] that may represent a single transcription unit.” Thus, as a corollary, the gradual selection of teosinte to improve its grain size, quality, or nutrient value could only have occurred after Tga made its appearance and not before. Both ideas were rejected mostly by those who followed the Old World domestication model for maize and who could not accept the idea of a Maizoid Eve, that is, with a few exceptions [10]. In contrast, anthropologists, for good reasons or bad, have seemed to relish the new controversy that “first for sugar, then for grain” has engendered [78, 89]. Keep in mind that Teosinte glume architecture, Tga, was “created” by John Doebley and his co-workers [27] from a suspected soft-glumed maize gene mutant backcrossed repeatedly into teosinte, thus producing a reasonable facsimile of what the ancestral teosinte mutant might have looked like. Because this ancestor has never been seen in the wild, the artifact is, therefore, only an approximation, brilliant and innovative as that reconstruction was. In the same way, we still have only the haziest notions of what the earliest stages of maize domestication might have looked like; for even the oldest, 6250-radiocarbon-years-old, protomaize ears from Guila Naquitz Cave, are already far advanced [10, 74]. But the fact is that this one-in-four-million, or even much rarer, mutation, according to Beadle’s teosinte mutation hunts, could only have been picked up by a fortuitous accident within a teosinte population already well-known and used “not for its grain but for its sugary pith or other edible parts” [57]. It is, therefore, most fortunate for all of us that these Mexican hunter–gatherers recognized the mutant’s worth, and managed, somehow, to save it for posterity. Admittedly, this is all based on negative evidence and on the assumption that these preagricultural societies must have used wild teosinte plants for many years in many ways, even after bringing it into cultivation. Thus, “the inhabitants of Guila Naquitz and Coxcatlan [caves a millennium later] were predominantly foraging on the most abundant local plants and that cultivation appears to have been insignificant at those locations” [14]. In fact, as Jonathan Sauer wrote [quoted in 57, p. 36], “The archaeological record in various regions of Mexico and North America shows that people did not switch from hunting and gathering to food production as soon as they had maize [read teosinte]. Rather, they planted some corn [read teosinte], probably as more of a snack than a staple and remained primarily reliant on wild food sources for centuries” or even millennia. The substitution of teosinte for maize in the previous quote, grown not for grain but for sugar and vegetable and, as Jonathan Sauer says, “more for a snack than a staple,” gives us a hypothetical picture of what the initial domestication scenario of Zea

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mays in some messy kitchen midden proto-garden might have been like [64]. Thus teosinte’s crisp, green ears were eaten occasionally, the pith made into an alcoholic drink; or used, inadvertently, as trellises for legumes and other vines that, to this day, still often climb up teosinte culms; or perhaps even for its stems as construction material used for windbreaks (Figure 3-2B). It is easy to forget that a well-grown teosinte is a plant not easy to ignore: large, abundant, and filled with sugar and decorated with crisp, green ears, these people must have known it well for many reasons and many seasons, even if leaving no evidence of ever having used CFCs before that critical mutation. It is also easy, therefore, to be confused by the chronology if, on the one hand, you follow the Old World domestication model, and if, on the other hand, alternate uses cannot be imagined. N. A. Federoff [30, p. 1158] correctly points out that “however useful to people, a Tga mutation [that opened the CFCs] would have been detrimental to teosinte, making it more vulnerable to destruction in the digestive tract of the consumer [e.g., deer] and so less able to disperse its seeds. Thus, the only way this mutation could have persisted is if our ancestors propagated the seeds themselves.” However,

the statement “. . . that people were not only harvesting— and likely grinding and cooking—teosinte seeds before [emphasis added] these [Tga] mutations came along, but also were selecting for favorable features such as kernel quality and cob size . . .” is a highly questionable statement. In fact, this scenario is an excellent description of what must have happened over the hundreds of years after that rare and unique Tga gene mutation first appeared in that single “mother” plant or its immediate local descendants. Its liberated naked and harvestable grains were recognized as useful, and its CFCs gradually modified over the next millennium into the type of proto-maize ears we now know well from Guila Naquitz Cave [10, 74]. That the Tga mutant did not originally appear in cobs but in the CFCs of the highly fragmentable teosinte ears is worth remembering [27] because cobs did not appear in the archaeological records until nonfragmenting maize ears made their appearance approximately 2000 years later, and no one would select for kernel quality if one could not get at the kernels (i.e., grains) and use them. As for harvesting and grinding there is, unfortunately, no premutation evidence, even though CFC fragments would have survived in the archaeological record literally forever.

FIGURE 3-3 Annual teosinte and quantitative trait locus (QTL) tb1. Teosinte branched 1 (tb1) is a maize architecture mutant that “makes the plant resemble a branched teosinte plant,” [22, 26, 27, 55, fig. 1, 57]. When teosinte grows in full sun without competition, tb1 is not expressed, and allows long branches tipped by tassels, as in (A); with increasing competition (B–D), its levels rise, lateral branching is suppressed, to result in less branched and unbranched maizoid growth forms. Tb1 was probably first favored concurrent with increased apical dominance when people started maize cultivation. But even until recently, there are cultivars with long shanks (30–40 cm), such as “Cocke’s Prolific” of the Gulf Coastal Plain as reported by Montgomery [71, p. 156]. The candelabra-branched plant of Z. m. mexicana (on the left), from 5.5 kilometers northeast of Los Reyes in the Valley of Mexico, is drawn from exact internode measurements, except for its diagrammatic ear clusters on its left hand side. © H. H. Iltis, 2005.

Origin of Polystichy in Maize

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Open-grown Annual Teosinte (diagrammatic) (ear clusters not shown except in insets) A0 tassel maturation gradient

main tassel

tassel spike

leaf

A1

tassel

tassel

tassel spike

main stem (culm)

primary branch

A1

prophyll

A3 2 A branch length and internode number gradient

A B female-male sexual and maturation gradient

Modified from Camara-H. and Gambino, 1990.

FIGURE 3-4 Annual teosinte (Zea mays ssp. parviglumis or Z.m. ssp. mexicana). Diagram of branching pattern of Figure 3-3A: Ear cluster in box A, terminating in a small tassel, enlarged in Figure 3-5A; that in box B, being larger and closer to the main stem and the zone of female hormonal expression, hence all female, enlarged in Figure 3-5B, modified from Cámara-Hernández and Gambino [16].

Federoff [30, p. 1158] then continues with a partly correct, but again chronologically misplaced, observation that such a scenario “suggests a ‘bottleneck’ in corn evolution: Several useful GMs [Genetically Modified organisms: this is nonconforming and undermining—deliberately(?)— the current usage of this concept] were brought together in a single plant, and then the seeds from this plant were propagated, giving rise to all contemporary maize varieties” [17]. That single plant here is, suspiciously, the same as my idea of a Maizoid Eve, the Tga mutant, which only after its appearance, and then with selfing and backcrossing to wild teosinte leading to introgressed populations subject to human selection, was able to escape its bottleneck and to become the ancestor of all contemporary maize.

FIGURE 3-5 Branching pattern of teosinte axillary inflorescences (ear clusters): based on Zea diploperennis Iltis et al., the most primitive teosinte, drawn as if uncondensed. (A): Secondary branch (A2) tipped by a small tassel that, with continuing shortening of branch length would undergo homeotic sexual conversions into an ear. The lower (distal) simple ear cluster, enlarged in Fig. 3-6A, shows branching at its most basic. (B): Ear cluster from near base of primary branch axis (A1), hence all female, with the secondary branch (A2) tipped by an ear. Such ear clusters would presumably skip the first steps of the hypothetical homeotic sexual conversions (translocations), with their terminal ears becoming maizoid more directly. This text is boldfaced to emphasize to the reader that the latter is the more common route to the maize ear, although bisexual ears with male tails (or with only their stubs surviving), common near the tips of primary branches and sometimes recovered from archaeological maize, point to the fact that homeotic sexual conversions can and do occasionally take place.]) (All diagrams modified after Cámara-Hernández and Gambino [16]).

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FIGURE 3-6 Branching and maturation sequence within a simple teosinte ear cluster. (A): Diagram of a simple teosinte ear cluster: This is, technically, a rhipidium, a fan-shaped, sympodial, cymose, typically Andropogonoid branching system, with lateral branches (tipped by ears) developing alternately in opposite directions. Each triangle represents a cupulate fruitcase (A and B modified after Cámara-Hernández and Gambino [16]. (B): Simple teosinte ear cluster, in cross-section. (C): Numbers indicate the maturation sequence of ears in (A) and (B). Only after ear 1 is well on its way toward maturity will ear 2, then ear 3, and so on, become fully mature, the lowest order ear (ear 1 on A3) intercepting and preempting their nutrient supply, and so setting up a nutrient-demand gradient leading to its apical dominance. Of the two bottom diagrams, the left shows axes or ears (A) and prophylls (Pr) in detail; the right, the zig-zag nature of ear cluster branching.

But because we do have the proto-maize ears from Guila Naquitz Cave (6250 radiocarbon years BP), still distichous but nonfragmenting and, as Benz [9] showed, with ear C already with pedicelled spikelets reactivated and well on the way to becoming maize, we must assume that it took Tga, and simultaneously QTL teosinte branched 1 (Tb1) (Figure 3-3) [9, 22, pp. 49–52], to shorten the internodes and initiate the domestication process, and not any generalized, preTga CFC improvements based on gradualistic, orthodox Old World models of domestication. Lastly, as far as improvements of teosinte grains are concerned, selection for larger grains did not occur until much later, after the earliest small-grained Tehuacan ears (ca. 4500 BP), which were already fully domesticated [11]. Selection for higher nutrient value did not soon occur either because, in fact, the nutrients in teosinte grains are much more concentrated than in maize [54, I. E. Melhus, in litt.]

and were subjected, but again much later, to selection for greater starch content and many other interesting attributes— some nutritive, others simply agricultural, such as the explosion of grain colors to identify landraces, or simply for the sake of their natural beauty (Figure 3-20) [62; 57, pp. 37–38].

THE CUPULATE FRUITCASE AND THE EAR CLUSTER: ADAPTIVE MARVELS OF COORDINATED SEQUENTIAL MATURATION The morphology of CFCs—sleek, hard, and superbly adapted for dispersal of their single, permanently imprisoned grains—is the acme of Andropogonoid seed dispersal specializations, the mother of all deeply canalized syndromes, and essentially uniform in all taxa of teosinte,

33

Origin of Polystichy in Maize

hence, an evolutionary ancient specialization dating back several million years to the origin of Zea (Figures 3-7A–C; 3-8A, B; 3-9B). Their developmental completion depends on a strictly controlled, hierarchically staggered, sequential maturation system of the ears within the fan-shaped cymose ear cluster, technically a rhipidium (Figure 3-6) [57, p. 22, Figure 4], which is an adaptive system, as described by Camara-Hernández and Gambino [16] that, once destroyed by that rare Tga mutation, was predestined to have allimportant, crucial consequences to the evolution of apical dominance and, hence, to the origin of maize. During their development, all ears within a teosinte ear cluster are eventually delivered roughly the same amount of nutrients, but each ear has to await its turn: not until the demands of the first ear for the necessary nutrients to flower and mature are partly fulfilled does the second ear get its share, and so on down the line to ear six or seven, a few days, weeks, or a month later (Figure 3-6). This sequential nutrient competition among the ears during their maturation goes on not only within one cluster, but also simultaneously among the ear clusters on one branch, the hundred or so ear clusters on a big teosinte plant, and eventually, to a lesser extent, the several ears of a prolific cultivar of maize [1, 57]. The maturation of the hundreds of ears in a large teosinte plant are staggered often over several months, and their CFCs are all hard, highly polished, and beautifully adapted to internal, mostly mammalian dispersal or for dispersal by gravity as well. In November, when the strong westerlies off the Pacific Ocean, helped by flocks of birds or various rodents, rattle showers of CFCs out of the clustered, bonedry dispersal “tubes” (formed loosely around each, now fragmented teosinte ear by the bladeless, small ear spathe at its base and its subtending prophyll) onto the ground, they blend in immediately like so many pebbles of gravel, lost within seconds even to the sharpest eye, all beautifully camouflaged by an astounding diversity of color markings of black-brown or light brown to pale green or ivory, each pattern strictly uniform within one plant and in no two plants exactly alike. Within a few weeks they fade to the dull brown of dry earth, whether in the arid wild or the arid herbarium. That the CFC production system can shut itself off when there is drought is obvious. For late in the season, in November or December, or in a dry year, or even earlier in plants deprived of water, the large number of soft, snow white, empty and sterile CFCs that tumble intermixed out of a bentover teosinte plant are witness to a system ideally adapted to the highly seasonal and often quite erratic savanna climate of southern Mexico. For anyone appreciating the abundance of CFC production in the field, it must be quite obvious on the one hand that these fruitcases can be easily collected in enormous quantity without much effort; and on the other hand, that they are so hard and indestructible, and so distinctive even

A

B

C

D

E

FIGURE 3-7 Teosinte ears, normal and mutated, and teosinte tassel branch. (A–C) Female (ears) and (E) male (tassel) inflorescence branch of Zea mays ssp. mexicana, race Chalco, the annual teosinte of the Valley of Mexico: (A) side view of ear (left is adaxial); (B) front (abaxial) view of ear; (C) longitudinal section of (B), showing a single grain enclosed in each of the eight fertile cupulate fruitcases; (E) front (abaxial) view of a tassel spike or tassel branch, which are all identical in teosinte and readily disintegrate by abscission layers, whereas maize tassels, with a much thicker central spike and lacking abscission layers, do not. (D) Mutated female inflorescence (ear) of Zea mays parviglumis (adaxial view) homozygous for maize allele Tga 1 (teosinte glume architecture 1) [26]: rachids are shallower (1.5–3 mm), more open, allowing the grains to be exposed (see Figure 3-8A, C, D) and humans to harvest them for food. (A–C) from Ixtapaluca (Iltis and Doebley 10b), (E) from 5.5 km northeast of Los Reyes Iltis et al., (769); (A–C, E) drawn by Lucy C. Taylor, (D) modified from material and photograph courtesy John Doebley, drawn by Kandis Elliot. © H. H. Iltis, 2005.

when fragmented, that if had they been used in any way whatsoever they would have entered and survived in the archaeological record and would have been identified as such by now [31].

THE ORIGIN OF POLYSTICHY IN MAIZE An Abbreviated History The enigmatic evolution of the massive polystichous maize ear from the ancestral slender distichous teosinte ear

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A

B

C

D

E

FIGURE 3-8 CFCs: Cupulate fruitcases (CFCs) of Balsas Teosinte (Zea mays ssp. parviglumis), normal and mutated by Tga 1 [From 57, p. 24]. Top row: In A and B, grain is permanently and tightly enclosed by the deep, hard, indurated CFC, made up of a cupule and the hard, outer glume of the enclosed spikelet. In C, D, and E, the grain is exposed by a shorter, shallower cupule that forces the grain to project outward and a thinner outer glume. This allowed easier grain removal that, partly due to a presumed weak, predomestication attachment, can be correlated with its original permanent imprisonment by the CFC. Bottom row: Mutated CFCs dissected, with grain freed of the CFC and bracts, homozygous for maize allele Tga 1, that, according to Dorweiler and Doebley [26], “represents a simple gene with a dramatic phenotypic effect [that when genetically introduced into teosinte is the] key step in maize evolution” [27]. That Tga, concurrently, by releasing the lethal CFC’s pressures suppressing the dedicellate spikelet’s primordium, allowed its automatic reactivation from the very start, is an unexamined possibility of key importance as well (Iltis, unpublished). Superrare, and transferred genetically from maize to teosinte, Tga has never been located in wild teosinte (C–E courtesy of John Doebley; photographs by Claudia Lipke). © H. H. Iltis, 2005.

has for long been a challenge to morphologists. My late, much lamented friend, W. H. “Herbie” Wagner (personal communication), could hardly contain himself when he rhapsodized that, “morphologically, the seeming extraordinary evolutionary explosion that accompanied the beginnings of maize are almost unthinkable, no matter how firmly the homologies and transformations are established.” And yet, if you think about teosinte and maize symmetry, the sequential changes were almost inevitable.

The “Twisted Cob Hypothesis” of Collins: Its Merits and Follies The first morphologically reasonable and widely accepted theory is the “Twisted Cob Hypothesis” of G. N. Collins [18], an active United States Department of Agriculture (USDA) maize researcher, who published an influential paper based on his own large, continuous series of some 400 hybrids between Zea luxurians (Durieu &

Origin of Polystichy in Maize

FIGURE 3-9 Teosinte to maize, a morpho-evolutionary series. A, Young ear of Chalco teosinte, terminal on secondary or tertiary branch near apex of primary branch, hence with male spikelets at apex; B, the same, but mature and disarticulated into individual cupulate fruitcases; C, ear of backcross showing maize introgression, with grain removed from the two lowest, now open, cupules; D and E, popcorn × teosinte hybrids showing front and back of 2-ranked, 4-rowed ears, the alicoles approaching the “yoking” envisioned by Collins (1919); F, a ca. 5-ranked, 10-rowed popcorn ear, showing grains not much larger than those of teosinte. Santa Ana Huista, Huehuetenango, Guatemala. January 9, 1976, Iltis, s. n. Photo © H.H. Iltis, 2005. Also appears in color insert.

Ascherson) Bird, the Guatemala or Florida teosinte [23], and a small-eared popcorn called “Tom Thumb,” and diagrammatically illustrated by him in Figures 3-13 and 3-14. To make a long story short, every conceivable intermediate was produced, from plants that were almost pure teosinte to those that were almost maize. The fact is that these uninterrupted series reflect the evolutionary history of maize and gave then, and still do now, a reasonable explanation of the morphological changes that took place during domestication.

What Happened After Tga 1 Caused the Maizoid Revolution? Maize domestication after Tga 1 must have involved both unconscious and perhaps deliberate selection for ever-

35

greater condensation, for its effects changed vascularization and countermanded fragmentation (Figures 3-7A–E, 3-9A–F). Thus, from the uniseriate arrangements of alicoles in teosinte, where the triangular CFCs (alicoles) sat, zig-zag fashion, one on top of the other, facing alternately left and right, increased condensation caused them to slide away from each other horizontally and closer vertically, so that with time, condensation not only widened and shortened these proto-maizoid ears to produce somewhat flat, biseriate structures that were able to accommodate more alicoles than the ears of teosinte but also were structurally more stabilized by their stronger horizontal and vertical vascularizations. Concurrently, as these once alternate alicoles slid sideways into their new positions, they literally abandoned their abcission layers that at maturity caused the fragmentation of the already fragile teosinte ears into their individual CFCs. Not only did they undergo some genetic changes that weakened these abscission layers, as we can predict also happened in the tassels [85, p. 319, Figure 23], but also, by losing contact with the neighboring alicoles above and below, they left their abcission layers behind, this an interesting but unappreciated insight illustrated by the artistically talented Walton C. Galinat [39, 40, p. 322, Figures 10–12; 41–43]. As Galinat [42] described Collins’ Twisted Cob Hypothesis, “When a threshold in compression created by the condensation is reached, relaxation and its associated space for the differentiation of spikelets is gained by pinching and twisting the expanded primordia off to one side. As a result of this slippage, higher order of ranking became associated with increasing levels of condensation.” These rather contrived scenarios could account for some, but not all of the ranks one finds in maize (e.g., 5-ranked, 7-ranked, etc.) and led to the search for alternate hypotheses such as the “Second Bifurcation.”

Collins’ Figure, With All of Its Faults, Is a Classic Illustration Collins’ [19] famous paper has been mostly ignored, and his illustrations never carefully discussed. Mangelsdorf [67] briefly mentions Collins; but, in fact, in his massive monograph, Mangelsdorf does not include any illustrations that show the symmetrical disposition of the spikelet arrangements in either male or female teosinte or maize ears. In Figure 3-13, Collins’ [18] diagrammatic illustration and its legend is reprinted, except for adding the shading to four of the spikelets. In Figure 3-14, the whole illustration is copied again, but with the figures dealing with his “twisting” hypothesis (A, C, E) reoriented so as to present the ears like a floral diagram, with the plant’s axis symbolized by an (X) on top, the adaxial (back) side placed underneath, and with the abaxial (front) side facing the viewer. Collins himself evidently did not appreciate the importance of such

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H. H. Iltis

A

B FIGURE 3-10 A, Diagrammatic longitudinal section of a “sweet corn” ear, showing naked, exposed grains permanently but weakly attached by elongate pedicels to ear axis (or cob); soft spikelet bracts (lemmas, paleas, and glumes) barely enclosing the base of the grains; inner glumes barely touching the rachis flap of the cupule; embryos facing the tip of the ear; and, sunk deep into the pith within, the hard, indurate empty cupules, wherein the teosinte grains, once upon a time, 7500 or 8000 years ago were permanently imprisoned. University of Wisconsin Botany 761, Agrostology class handout, 1958, drawn by H.H.I. © H. H. Iltis, 2005. Also appears in color insert. B, Longitudinal section of young ear of a Mexican landrace (probably Conico), with husks removed. Young spikelets and vascular systems stained overnight with diluted ink, showing grains still enclosed by spikelet bracts, with the hard indurate tissues of the cupules, and the longitudinal vascular system and the soft central pith forming a cylinder of remarkable strength. Xalapa, Veracruz, June 1981. Photo © by Iltis 2005. Also appears in color insert.

Origin of Polystichy in Maize

FIGURE 3-11 Longitudinal vascular system. Strong, more or less independent, longitudinal vascular system bearing now empty floral bracts, surrounding the white pith. An old “corn cob” that is now partly breaking up along lines separating individual ranks (the central two pieces), with the old husks on the shank remaining attached. From a messy farm yard near Madison, Wisconsin. © H. H. Iltis, 2005.

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38

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H. H. Iltis

B FIGURE 3-12 A, Vascularity in the maize ear. Cob of young sweet corn, discarded (after consumption of grain) and buried under wet leaves in the forest to rett over the winter, showing major vascular systems: from inside the pith looking outward at the interactions between the vertical with the longitudinal parts of the inner (axial of Reeves, 1950) vascular system supplying the grains, forming “cupule baskets” holding loosely the “cupule linings,” these hard, (apparently?) nonvascular outer layers of cupule induration that may be lifted out with a forceps. Photo © H. H. Iltis, 2005. B, Vascularity in the maize ear. The reverse view, looking from the outside in, showing on right side one loose “cupule lining” and on the left side two “cupule baskets” with their “cupule lining” removed. The delicate outer (peripheral of Reeves, 1950) vascular system supplying the cupule and bracts is evidently partly lost. And is the young cupule lining really nonvascular? The orientation of the photos is uncertain, with top the front end of the ear? Photo © H. H. Iltis, 2005.

alignments, for all three of his drawings (see Figure 3-14A, C, E) are pointed in three different—and none in the correct—direction. Nevertheless, Collins’ theory, as ingenious and path breaking as it was, was contrived and basically incorrect.

The Origin of Polystichy in Maize: The “Second Bifurcation”—A Reappraisal In “Inflorescence development in the ‘standard exotic’ maize, Argentine Popcorn” [80], the ear and tassel ontogeny of this 4-ranked, 8-rowed, rather primitive landrace is both described and beautifully illustrated with scanning electron microscope (SEM) photos, to expand on Sundberg and Doebley’s [80] radical new working proposition that the

origin of polystichy in the maize ear is caused by a second bifurcation. In opposition to Collins’ [18] ideas of “twisting,” for which they could not find any evidence in the ear, they proposed that rank number (the number of double rows of grain) was increased through a shift in developmental timing, by allowing alicole primordia to go through two bifurcation events instead of only one before each alicole finally produces the spikelet pair primordia (spps) that then would mature into the paired sessile and pedicellate spikelets. How that would then result in decussate paired alicoles, which they report again and again as occurring in both tassel and ear apical meristems, is not made clear. Furthermore, how one would get tricussate, 3-ranked, 6-rowed ear, as illustrated by Galinat [38, p. 463], is a similarly good question (cf. Figures 3-15E and 3-15F).

Origin of Polystichy in Maize

39

A

B

D

C

E

FIG. I.—Diagram showing arrangement of pedicelled and sessile spikelets in A, undifferentiated four-rowed branch; B, eight-rowed ear, the result of the fasciation of two undifferentiated branches; C, eight-rowed ear the result of twisting a single undifferentiated branch; D, r6-rowed ear, the result of fasciation; E, r6-rowed ear, the result of a further twisting of “C.”

FIGURE 3-13 Collins’ 1919 diagrammatic cross-sections of tassel spikes of teosinte or maize or, by inference, of the maize ear. Reproduction of Collins’ [18, p. 129] Figure 1 and its legend, altered only by shading in E of the two adjoining sessile spikelets, indicating their abaxial (front) position, and the two adjoining pedicelled spikelets, indicating their adaxial (back) position. The letters a in D and E indicate his view of single “dropped rows,” a mistaken notion (see text). That Collins actually believed in a literal “twisting”—like that of a rope—is shown by his legend to E. His drawings (A, C, E) show the proper, relative positions to each other of the sessile—pedicellate spikelet pairs on a tassel spike or maize ear, a pioneering, but unappreciated scientific insight, for which Collins deserves credit. A, Yoked pair of alicoles (Collins’ useful term for a rachid [cupule] plus its attached paired spikelets); C, Two decussate, paired, yoked alicoles from two successive “nodes” of a maize tassel spike (one above the other, but enormously contracted in the maize ear, producing an 4-ranked ([8rowed] ear); E, four quadricussate, paired, yoked alicoles, with two each at successive nodes, if pistillate, producing an eight-ranked (16-rowed) ear. B and D are diagrammatic representations of the 1880 fasciation-fusion hypothesis of Paul Ascherson [5], here proven erroneous by Collins simply because of the incorrect arrangements of their spikelet pairs (see Collins’ legend to Figure 1, reproduced above). Modified from Collins, 1919.

At the end of a an interesting paper that tries nevertheless too hard to make the point for a second bifurcation, Sundberg and Orr [83, pp. 1264–1265] tack on an interesting and tantalizing observation: “It seems likely, however, that the primary mechanism responsible for the shift from distichy to polystichy during the evolution of maize may have involved the transition from distichous to spiral phyllotaxy, a process that occurs ontogenetically during development of very young inflorescence meristems.” This is a significant statement that is pregnant with meaning. Whether it is truly spiral is a matter of semantics, but it is perfectly obvious that what these eminent morphologists saw was the meristem of the developing shank.

FIGURE 3-14 Structure and orientation of tassel spikes of teosinte or maize, or, by inference, of their homeolog, the maize ear: Collins’ Figure 1, reoriented to show proper positions of cross-sections with respect to the plant’s axis (X): adaxial or back (top), abaxial or front (bottom). Note that adaxial, or “back,” is always indicated by paired pedicelled spikelets (shaded, one each from adjacent ranks) and abaxial, or “front,” by paired sessile spikelets (shaded, one each from adjacent ranks). A, a pair of yoked alicoles (as in a teosinte tassel spike or branch [or in a two-ranked protomaize ear, e.g., Guila Naquitz ear C of Benz [10, 32, 74]. C, two paired yoked alicoles, decussate, 4-ranked (8-rowed), from two successive nodes of a tassel spike. In the primitive 8-rowed maize ears, the two pedicelled spikelets in back are usually separated by a large gap due to adaxial flattening that distorts the apical meristem facing the axis, but reapproach each other during further development; E, four, paired, yoked alicoles in quadricussate arrangement from two successive nodes, producing an 8-ranked (16-rowed) ear. Cupules not shown by Collins, but here (in A1) diagrammatically indicated as a depression abaxially to each spikelet pair. B and D are diagrammatic representations of the fasciation-fusion hypothesis of Ascherson [5], here proven erroneous by Collins simply by the incorrect arrangements of their spikelet pairs (see Collins’ legend to Figure 1, left above). From Collins 1919 and original © H. H. Iltis, 2005.

THE SHANK AND ITS HUSKS— THE KEY TO MAIZE EAR POLYSTICHY Maize Polystichy—With Its Roots in the Shank to Its Glory in the Ear The present chapter hopes to present the “harmonious theory” that was so desired by Paul Weatherwax [86, pp. 112–113] on the origin of polystichy in the maize ear from the distichy of the ancestral teosinte ear and finally bring this long-lasting controversy to a resolution.

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FIGURE 3-15A–F Biradial symmetry and grain attachments in maize ears. A and B, cross-section of a quadricussate eight-ranked (16-rowed) ear. A, Paired grain attachments on two successive nodes, with one level distinguished by less-exposed vascular strands (marked with dots on paired grains by the author) to emphasize double rows, (i.e., ranks). B, Same ear as in A: Each rank is composed of an adaxial row of pedicelled spikelets (PS) and an abaxial row of sessile spikelets (SS). Thus, the ear exhibits biradial symmetry, with the left half a mirror-image of the right half, with the exact center of the back (adaxial) always identified by PS/PS, and the front (abaxial) by SS/SS, in each case from adjacent ranks. In modern maize, pedicel lengths differences have long since been lost. Theoretically, the spikelets of opposite ranks represent “yoked alicoles” of Collins (1919). (Photo from Kiesselbach [63a, modified], who accepted Mangelsdorf and Reeves’ [68] “Tripartite Hypothesis,” and did not discuss the symmetry of the maize ear at all (C and D). C, Cross-sections of eight-ranked (16-rowed) sweet corn, and (D) of a 4-ranked (8-rowed) unnamed but relatively primitive Mexican land race, to show grains from two successive nodes, with one of the levels distinguished by V-shaped paired pedicels. D, Note thick glumes at base of the two paired ranks, and the slight difference in pedicel length in the alternate pair. (C, Sweet corn, cult. Madison, WI; D, landrace from maize field at km 73, 1400 meters, 6 kilometers west of Teloloapan on road to Arcelia, Guerrero, Mexico; Iltis & Cochrane, s.n.). Photo © Iltis 2005. E and F, Crosssections of 6-ranked (12-rowed) maize ears. A, shallow-cupuled, short-pedicelled types common in South America; and B, deep-cupuled, long-pedicelled types common in North America (Drawings by Walt Galinat, [38, p. 463]. The alternating arrangements of the alicoles in two interdigitating triplets from successive nodes suggest a pattern due to two successive tricussate nodes generated in the apex of the shank. (Discussion in text.)

First of all, I report on some simple morphological analyses made over the past 8 years of 40 shanks, husks, and ears of “sweet corn” bought at the Farmers’ Market in Madison, Wisconsin. The results given here in Table 3-1 and in Figures 3-16 through 3-19 [cf. 57, pp. 33–34] support the emphasis Collins [18] and Sundberg and Orr [81, 83] and

others placed on condensation but shifts attention from the butt of the ear to the upper compressed nodes of the shank, a much unstudied structure. The most remarkable characteristic of the shank proved to be the gradient in husk phyllotaxy, which changes from an open teosintoid distichy at the base to a condensed maizoid polystichy at the top. Sur-

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Origin of Polystichy in Maize

TABLE 3-1 Analysis of 17 Shanks, Visible Nodes (cf. p. 42), and Husks of Sweet Corn, Bought from the Farmers’ Market, Madison, Wisconsin, 1998–2005

“Sweet corn” ear number (grouped by purchase)

Husks/node shank base→apex Prophyll (II)→ear base outer (lower)→inner (upper)

Rows/ranks of grain

Shank length (cm)

Nodes/shank

Husks/shank

1

12/6

21

8

12

2

16/8

12

8

11

II 1 1 1 1 1 2. 2. 3. II 1 1 1 1 1 1 2 3

3

14/7

12

7

11

II 1 1 1 1 2 1 4

4

16/8

8

8

10

5

18/9

8

9

18

6

14/7

12

7

12

II 1 1 1 2. 2. 3. II 1 1 1 1 2 2 2. 4. 4. II 1 1 1 1 2 4. 2.

7

16/8

16

9

14

8

16/8

16

8

15

II 1 1 1 1 1 2. 3. 4. II 1 1 1 1 2 2 3 4

9

20/10

20

8

16

II 1 1 1 1 2 3 3 4

10

16/8

18

6

12

II 1 1 1 3 1 4

11

16/8

14

5

10

II 1 1 2 3 3

12

18/9

11

6

10

II 1 1 1 2 1 4

13

14/7

11

6

12

II 1 1 1 2 3 4

14

18/9

18

8

16

15

14/7

7

6 (8?)

12

II 1 1 1 1 2 3. 4. 3. II 1 1 2 1 1 1 5

16

12/6

10

5

13

II 1 2 2 4 4

17

14/7

7

5

13

II 2 2 2 2 5

The columns are self-explanatory. Note that number of husks/shank (columns 5 and 6) is always higher than the number of nodes/shank (column 4). In column 6 (far-right) symbol II signifies the two-keeled prophyll, the numbers that follow the number of husks/node [if added, totals should equal column 5], which increases as you go up the shank. That the total number of husks equals the number of single rows of grain proves rarely to be true, but most other times is way off the mark. More likely is the notion that “ranks of grain” (column 2) is determined by axillary meristem potential in the husks of the uppermost two or three nodes (column 6, far right), these here underlined if their total equals the number of ranks, and underdotted if the number is off by one, either way. The coincidence is suggestive, yet, because of extreme crowding at the top of the shank, the difficulty of assigning husks to specific nodes should be recognized. Ears 14 and 15 are illustrated in Figure 3-16 (here with the center husk insertion indicated by a toothpick, a useful technique); ear 6, in Figure 3-17; ears 1 to 5, in Figure 3-18; and ears 2 and 5 to 7, in Figure 3-19. (Please consult p. 42, M. Sundberg’s comments, added after manuscript was finished, on visible nodes, such as are listed here, which equal the compound or compressed nodes of the developmental morphologist.)

prisingly, it thus moves the ontogenetic origin of the maize ear’s polystichy from the ear’s apical meristem downward to that of the uppermost, strongly compressed nodes of the shank, each of these supernodes, or compound nodes, always bearing several polystichous husks in a circular arrangement [cf. 77]. Secondly, these findings, clear cut and universal as they seem to be, are concordant with the short and brilliant but totally forgotten and uncited study of G. S. Stephens [79], whose hypothesis, herewith rehabilitated and named the Shank Polystichy Theory (SPT), not only verifies my own findings, but adds significant additional insights to the conclusion that the polystichy of the maize ear is solidly rooted in the polystichy of the upper nodes of the shank. Ultimately derived from the peduncle of the ancestral teosinte ear by way of a telescoped primary branch, this newly verified shank morphology should bring an often acrimonious controversy to a harmonious close.

On the Inexcusable Neglect of the Shank and Its Husks As all-important a crop as maize is, one would think that the shank on which that golden ear sits and the husks that envelop it and protect it forever and prevent its grains from dispersing without human permission, would have caused them by now to have been repeatedly investigated in depth. With the exception of Stephens [79] and Nickerson [73], who briefly discusses Stephens’ paper, the slate is all but blank. The ignorance of the shank–husk system is equaled, of course, by the total lack of any and all shanks or husks in the world’s herbaria, not that the collections of maize ears, with few exceptions, are anything to brag about either. In fact, almost all the 10,000 ears of the famed country-bycountry surveys in the 1950s of the Races of Maize of tropical America, such as the ones for Mexico [90] or Colombia

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[75], were shelled and the seeds saved, but the cobs and shanks, both intricate structures containing much valuable information, were thrown out with the trash. So much for thinking of the needs of ethnobotany or archaeology! Not surprisingly, in the Races of Maize in Colombia, the descriptions fail to mention shanks, list only the average number of husks, and fail to mention rank number [75]. In fact, when Benz decided to compare the internal morphology of the maize ear in various Mexican maize races, he had to assemble his own, huge collection at the University of Wisconsin Herbarium [9]. But just on the face of it, like the cob inside the ear, the shank and its husks deserve more serious study. After all, the shank and its husks coevolved with the ear, are unique structures in their own right, and form, as Galinat suggested [40], together with the ear a unique, gargantuan, overgrown, terminal “bud” that never opens. They deserve to be paid attention to as well (see Table 3-1). And yet, there has been almost an unwritten conspiracy not to examine basic shank morphology, even when mentioned and even when fully illustrated as by Edgar Anderson [3]. The myriad papers about maize morphology, some even with excellent illustrations of shanks and, rarely, husks, go on and on about the husk’s protective role, or they skip right away from the description of the culm to that of the ear; or, if they rarely do discuss the shank and its husks, they are usually only half right or all wrong. They reflect generalizations based on one or two ears or on averaging the results of measurements of the internodes, or the author gets stuck trying to describe the husks and their “spiral” attachments, then settles on a description of the protective role they play without devising a way to get at the difficultto-get-at phyllotaxy. Hence, the detailed instructions that follow on how to study the shank and its husks in nine easy steps are long overdue. Admittedly, there are many good illustrations of naked shanks. What they do show well is the great variability in the number of nodes and internodes and in the length of the latter, which, usually long at the base of the shank, become increasingly shorter through condensation as they reach the top. But, surprisingly, almost all of these illustrations lack an analysis of the number of husks per node. Stripped of the husks, they leave one with the impression that each node bears one husk, and this impression is sometimes incorrectly reported and illustrated, as by Weatherwax [86, 87] and Anderson [3]. But in most modern mature maize ears the number of nodes and internodes is always less than the number of husks as shown in Table 3-1 [79]. So, what is going on here? Important Note: Marshall Sundberg (personal communication, September 2005) points out that in the maize shank and ear, “the number of visible nodes and internodes always appear to be less in mature ears, but developmentally there is still a 1 : 1 correlation between husk and node . . . although

it appears that underneath the mature ear there can be two or more husks/node, there are actually two or more very compressed nodes with little or no nodal elongation.” Whether you call them nodes, compound nodes, or supernodes, to the nonmorphologist they look like nodes with two or more husks each. In any case, the degree of compression internodes and nodes in the shank has a direct effect on ear polystichy, and it will be up to Sundberg and co-author Orr to reinterpret what this chapter is all about. In maize, human unconscious selection for increased condensation has often compressed two or three nodes into one, as one can readily imagine in watching out for the common slanted nodes, which represent a node on the way to fusion with the node above and/or below to make one, usually thicker node bearing two or three husks. Thus, we get opposite, decussate, tricussate, or quadricussate nodes with two, three, four, or more husks attached to a single supernode. This is especially true of the dense, whorled husks on the short apical internodes of some sweet corn and field corn cultivars evidently adapted by corn breeders to harvest machines, and illustrated in this chapter (Figures 3-16 through 3-19). As far as the number of internodes on the shank are concerned, they are said to equal in a rough way the number of internodes on the culm above the shank and ear insertion, using Montgomery’s [70] diagrammatic reconstruction of the maize ancestor (teosinte) as a theoretical template: The higher up on the culm, the fewer the internodes, the lower, the greater the number. The fact, of course, is that two opposing tendencies give conflicting results: On the one hand, in teosinte the often relatively longer upper branches tend to have one to three more internodes and, hence, more leaves than expected, whereas the lower branches (unless quite open grown and free of competition or shading) will have one to three fewer internodes and have fewer leaves; both of these anomalies are obvious adaptations to optimize photosynthesis (see Figure 3-3). In maize, this surprising (to some who do not know teosinte) anomaly has sometimes been noted but is countermanded by the degree of condensation in the shank. So both the plant’s basic response to photosynthesis and the conflicting result of human selection play havoc with generalizations.

A Note on Twisting, and the Basic Bilateral Dorsiventrality of Zea That all the authors of the second bifurcation could not find any evidence for twisting in the ear or its meristem, and that Collins’ theory on how decussation of the alicoles comes about by a contrived explanation involving twisting in the ear, is not surprising. The twisting, of course, occurred over eons of selection in the upper nodes of the shank because of fusion of nodes by one-fifth-turn or one-quarter-turn to

Origin of Polystichy in Maize

half-turn lateral displacements (twistings) of the husks’ insertions, that resulted in the husk phyllotaxy changing from distichy at the base to polystichy toward the top of the shank. By the time one gets to study the ears, the twisting was all over and done with, although the slanted nodes in many shanks (cf. Figures 3-16 to 3-19) tell us that nodal fusion caused by condensation is a continuing process that even now is still in progress [77]. Both teosinte or maize plants have a front and a back, and, thus, a left side and a right side, much like a human being (Figure 3-3A–D). Anderson [3, p. 17] was apparently one of the first who clearly stated that, “A corn plant . . . has a definite front side and back side, depending upon whether the outermost sheath edges turn toward the observer, or away from him.” It is worth mentioning, then, that the gyre of a curved, slanted shank node is either twisted left or right, depending on which side of the plant (i.e., right or left) the shank originated from. This is also a reflection of the maize plant’s basic bilateral dorsiventrality, just like the leaves on alternate nodes of the culm, although they all are attached to the culms’ backside, have their outer leaf margins closing over their inner margins alternately either from the left side or from the right side, as a 1948 drawing by Weatherwax [88, p. 318], copied [unacknowledged] by Anderson [3, p. 20] the following year, clearly shows. Starting with the outermost husk, they will alternate (based on the direction of the first husk’s initial overlap, which is opposite to that of the leaf sheath on the culm from which the shank originates), either from left to right or right to left, depending on which side of the culm they originate. So, the maize plant as a whole, including branches, husk insertions, and so on, is composed of two halves that are mirror images of each other. Thus, if you are facing the front of the plant, with the shanks and the ears arching out toward you and looking down a husked ear’s top, if the ear originated on the left side of the plant, the outer, visible, and presumably distichous husks are going to be overlapping clockwise, left right, left right, with the ear from a node above or below, arching out from the right side, the husks are going to be overlapping counterclockwise, right left, right left; viewing the husks on an ear from the top produces a lovely, herringbone pattern. Frankly, this is a subject in need of additional study on cultivars with long shanks, especially those primitive ones that are 4-ranked and 8-rowed. Although all these structural phenomena are not always obvious in the adult plant, they are much so in the seedlings, where the direction of overlap, whether from left to right or vice versa, shows in the first seedling leaf of the plumule. Incidentally, the plumule represents the first lateral branch of the germinating maize plant, with the bi-nerved coleoptile as its prophyll and with the embryonic plant’s main axis running from the primary root to the haustorial scutellum, according to the 1957 iconoclastic interpretation of Jacques-

43

Felix [61]. Looking downward at this lateral shoot from its apex, the seedling leaves are turned either clockwise (right or dextrose) or counterclockwise (left or sinistrose) in statistically equal numbers of seedlings (despite Weatherwax’s [88] erroneous objections)—a condition that finds its ancient, eight-millenia-old explanation in the alternating left-facing and right-facing basic bilateral dorsiventrality of the linearly arranged CFCs in the slender ear of the ancestral teosinte, as initially proposed in 1992 by CamaraHernández and Bellon [15]. But to fully describe the marvelous symmetry of Zea mays is another story for another time. Suffice it to say that its bi-lateral dorsiventrality should never be forgotten, for its innate rules set the directions for all of maize evolution.

Edgar Anderson and the Shank—The Story of an Unconsummated Love Affair Of all the professors that passed through my life in student days, no one except my professorial father had as great an influence on my life as Edgar Anderson, geneticist at the Missouri Botanical Garden and Professor at Washington University in St. Louis. He was loud and brash, with flashes of genius grafted on an enormous, selfdeprecating ego (“I am not a genius, but I am close enough to one to know what his problems would be”); he was ambivalently beloved as “Andy,” but no student would dare to call him that to his face. Always stimulating and bubbling over with genuine enthusiasm for plants and gardens, he furiously argued with me about grass taxonomy of which he knew little about and hardly ever talked to me of maize or teosinte, which as far as I know was not then grown at the Missouri Botanical Garden. Although I collected maize ears for Dr. Anderson in Costa Rica in 1949, I was Robert E. Woodson’s graduate student and learned more about maize from my good friend and fellow graduate student Don Duvick than from Anderson himself. But indirectly, both Anderson and my father [51], who wrote about sexual abnormalities in maize caused by the corn smut fungus, prepared me to pay attention to maize, which I did not really study until 1958 when I had to teach agrostology at the University of Wisconsin. When I then had to read all the major corn papers, I became convinced, with help from Galinat’s [34–37] beautiful drawings of the morphological phylogenetic series in which he arranged the ancestral genera and my own drawing of a longitudinal section of a sweet corn ear (Figure 3-10A), that these experts were for the most part all wet as far as the role of teosinte in maize evolution was concerned. Nevertheless, it was Anderson [2, 4] who designated the telescoping of the maize inflorescence axis as condensation, “defined as a kind of ‘controlled fasciation’ in which the internodes are or tend to become eliminated” [73, p. 87]. He also thought up the disastrous “Tripartite Hypothesis” [68],

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an albatross around many a maize researcher’s neck for 40 years, to which Mangelsdorf and Anderson, with great pride, held onto dearly almost to the end of their lives and that made the weedy, super-fertile teosinte an “unplant,” an odd, cytologically impossible hybrid between a Tripsacum and a hypothetical “wild maize.” And finally, tragedy on tragedy, it was this hypothesis that prevented both of these scholars from ever getting the maize evolution story quite right [66]. Yet, in the 1940s, Anderson published many papers on maize. One of these, with William Brown, was based, just like Collins’ earlier work, on the supposedly easier-to-study spikelets of the tassel, the ear’s male homolog, with the ear, shank, and its husks barely mentioned [4]. They did demonstrate the direct relationship between increased kernel row number and increased condensation, but never really understood the reason. Deploring the “fundamental difficulty” of interpreting the maize inflorescence, they asked: “Why should the lower branches of a maize tassel be distichous and the upper branches spiraled or whorled?” [4, p. 334]. This was an obvious question for which they could not think up a valid answer. And yet, as they then pointed out, in between the base and the top of the tassel, spikelets go through a gradient of condensation: They are at first distichous, then opposite to each other, then decussate, and finally whorled. Their explanation for these tendencies was simply that the tassel is “fundamentally distichous throughout.” Not much of an explanation! Well, yes and no. Had they only looked at the basal distichy and terminal polystichy (whorledness) in the phyllotaxy of the husks on the shank, they would have instantly realized that the gradient in the phyllotaxy in the tassel spike is exactly homologous to that of the husk leaves on the shank (i.e., a secondary, coevolutionary expression of how the changed phyllotaxy of the ear changed the phyllotaxy of its homolog, the tassel spike, the latter a structure that automatically coevolved, step-by-step, through human selection for larger, more apically dominant ears surrounded by a waterproof, pestproof, and water and CO2 sequestering husk system to protect the grains within [55].) But nowhere in their study are shank or husks mentioned or the basic homology to the tassel discussed. Without that insight, to them what happened in the tassel made no sense.

The Condensation in the Maize Shank and Its Husks and Preconceived Notions Understanding the maize shank has its problems, and one is not only faulty interpretation but preconceived notions and quick extrapolations that influence the observations. How easy it is to misunderstand shank morphology can be seen in Doebley and Wang’s [25, p. 362] interesting study of tb1, a QTL that functions as a growth repressor in maize. In low levels, it reacts automatically with the environment

(in teosinte, influenced by increasing levels of shade, competition, etc. (see Figure 3-3), and it causes increased condensation of the axillary branches, such as the shanks, by shortening their internodes). In maize, they claim, these are supposed to average “about 1 cm in length. Unlike teosinte, the number of internodes in the lateral branch [shank] is greater than the number in the main stalk above the point of attachment of the branch. For maize line W22, a branch attached at the fifth node below the main tassel will be composed of about 12 internodes and have 12 husk leaves” [25, p. 362]. There are at least two observations here that are not based on careful observation, aside from the finding that 12 internodes on the fifth node below the tassel seems a little high. One is the comment that the internodes “. . . average 1 cm in length . . .” Actually, that may well be the case, but to average measurements of objects that are arranged in a sizereduction gradient is meaningless, for one of the main attributes of all shanks is that their internodes (except, occasionally, for a single, short one at the base) always progress from long ones at the base to exceedingly short ones just below the ear. In other words, they exhibit a gradient of increased levels of repression the closer they get to the butt of the ear, which is a gradient that is highly significant. As for the second observation, a quick examination of the shank stripped of its husks, and then a longitudinal section through it with a kitchen knife, would have soon revealed that these 12 husks originated on only 5 to 8 nodes, with the uppermost decussate to pentacussate, and bearing anywhere from 2 to 5 husks each [57]. The number of husks, no matter what cultivar or landrace, is always greater than the number of internodes or nodes [79]. In fact, maize shanks (lateral ear-bearing axillary branches) will always have more husk leaves than internodes (or nodes), never an equal number. The latter is impossible, and for good reason, because the number of husks/node is correlated with the degree of condensation (repression), which, in turn, is correlated with the morphological gradient, which makes averaging internode lengths inappropriate. There are, indeed, hardly any publications except that of Stephens [79] that mention the shank and its husks and the meaning of the condensation gradient. One of the few is the interesting, but only halfway correct, comment by Kiesselbach [63a] that “the outer husks are distichous like ordinary leaves [on the culm] while the inner are polystichous, there sometimes seeming to be as many ranks [of husks] as there are double rows of its kernels.” The latter is never true (as one can see when consulting Table 3-1). When first published in 2000, the obvious great evolutionary significance of this admittedly highly variable gradient, from teosintoid distichy at the base of the shank to a mazoid polystichy at its top, was totally misinterpreted by none other than yours truly [57] when I wrote that “the developmental influence of maize ear polystichy transferred

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Origin of Polystichy in Maize

downward [sic] to the upper region of the shank [is] a no doubt indirect, inadvertent result of human selection aimed at ear polystichy but nevertheless probably of some adaptational value in producing a nearly airtight jacket around the ear that keeps out . . . insects . . . birds . . . rain, and possibly keeps in scarce moisture and high, potentially useful, [H2O] and CO2 concentrations” [55]. It never dawned on me until recently that the direction of influence must be the reverse, and that the shank husk or whorledness polystichy is the root of maize ear polystichy. Ontogeny does recapitulate phylogeny, and then only in 6 to 26 centimeters, and in every shank that ever bore an ear of maize.

FROM TEOSINTE DISTICHY TO MAIZOID POLYSTICHY: OR HOW TO STUDY HUSK PHYLLOTAXY IN NINE EASY STEPS The following instructions are an expansion of a methodology presented previously, which is simple to carry out, needs only a sharp, soft pencil; a box of toothpicks; and a kitchen knife; and gives accurate and easy-to-visualize results. (see Table 3-1, and Figures 3-16 through 3-19) [57, pp. 33–34]. They summarize with hard data the phyllotaxy of the husks and allow us potent insights into the enigmatic origin of polystichy in the maize ear. 1. Take a husked ear, one with the narrow, prominently 2-keeled or 2-nerved prophyll, or “first husk,” still attached; remove it and mark the short horizontal line of attachment with a black pen at or near the base of the shank. Important Note: You do want to distinguish the prophyll from the husk leaves (mostly leaf sheaths), for the presence of the prophyll indicates not only the center of the ears’ adaxial attachment to the culm (the main stem), but furthermore, that you do indeed have a complete husk system and its enclosed ear in hand, which is a very important consideration. 2. Identify the first (lowest, outer) true husk, find its tip, and then split it with your fingernails or simply pull it apart from the top down the middle along the central nerve all the way to the base. 3. With a sharp, soft (#1 or #2) pencil, puncture the husk at the center of its attachment to the node at its base and concurrently make a sharp, deep hole in the node with the pencil to mark the spot. 4. Remove the first husk leaf. Together with the prophyll, press and dry it in your phone book, for the whole series will make in interesting display. 5. Repeat the procedure with the remaining husks, until all husks have their center marked by a sharp, deep puncture on the shank’s nodes. Be extra careful near the top of the shank because these innermost husks are not only thin

but also crowded and are often inserted deeply underneath the lowest grains, so that your puncture will have to be made at a sharp upward angle. When you are finished, mark all the holes with the pencil again. 6. Now, if you want to find a way to be able to count the husks extra carefully and accurately, and make your analysis much easier, push a toothpick slowly but deeply into each pencil hole. 7. Write down the number of toothpicks in each node: one, two, three, or more, indicating the prophyll by the Roman Numeral II, and count the husks per node from the base on up (e.g., II 1, 1, 1, 2, 2, 3, 3); or list them in the following manner, connecting them by dashes if two or more husk are inserted on one node (e.g., II 1, 2, 3, 4–5, 6–7, 8–9–10, 11–12–13). 8. With a sharp kitchen knife, slowly and carefully, cut the shank longitudinally and transversally (horizontally) into two halves, from the base all the way into 5 to 10 cm of the ear, and then break the two parts apart, and count the crosssections of the nodes as they appear from inside the shank. 9. Optional: Repeat the procedure in five or more ears, and again with ears from other cultivars or strains, to illustrate both the enormous variability in the structure of the shank–husk system, but also the uniformity in the condensation and decussation trends and gradients. In all the ears you have discovered a teosintoid, alternate-distichous, horizontally disposed phyllotaxy at the base of the shank, with a single husk per node, to a maizoid polystichous phyllotaxy at the apex of the shank, with three to five whorled husks at each of the top two or three nodes. And with this the origin of polystichy in the maize ear is revealed.

Iltis and His Gigantic Footnote The significance of my own look at shank morphology, which, at the time I totally missed, first saw the light of day in an overly long, two-page footnote that described my method of measuring shanks and husks, what the results were up to that point, and ended with my conclusion that the polystichy of the ear infiltrates downward into the shank, instead of upward into the ear, the now so obvious and correct direction [57, pp. 33–34]. The realization finally came drifting in one fine snowy morning that, in fact, it is the shank that held the secret to the ear’s polystichy and not the ear’s apical meristem, an insight that has directly or indirectly permeated this chapter from the beginning and needs not now to be reiterated again, especially because Table 3-1 summarizes all the data, and the illustrations speak for themselves. What is incontrovertible is the obvious conclusion that the shank can transfer any of the possible numbers of ranks to the ear (but not rows, for they, like good soldiers, never break ranks), uninhibited by the evident limitations of second bifurcations or spatially forced decussations in the

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FIGURE 3-16 Husk phyllotaxy: Two ears of maize, with each toothpick indicating the center of a husk insertion to illustrate a methodology of studying maize husk phyllotaxy on the shanks (see text). Note in ear 14 of Table 3-1 (top) the distichous alternate husk dispositions at the shank’s base and the tricussate one at its top (i.e., at base of ear). In ear 15 of Table 3-1 (bottom), note the pentacussate node at the top of the shank (i.e., at base of ear). Photo by Claudia Lipke. (See p. 42; Table 3-1, and endnote to its legend; and section in text on How to Study Husk Phyllotaxy in Nine Easy Steps.) Photo © H. H. Iltis, 2005.

Origin of Polystichy in Maize

FIGURE 3-17 Sweet corn, with and without husks. Ear with husks and two-keeled prophyll attached (top). The prophyll’s broad central longitudinal stripe is adaxially (the side facing you) pressed into the culm’s concavity, with its keels grasping the culm, and abaxially covering the outermost “flag” bearing husk. Ear 6 of Table 3-1 (bottom), with husks removed: Note shank node 4, which is slanted, at base fused with node 3, at top with node 5; and node 6, which bore 4 husks, and node 7 (not visible, tucked deep under lowest grains) with 2 husks. Nodes 1 to 4 each bore a single distichous husk. Photo © H. H. Iltis, 2005.

FIGURE 3-18 Polystichy of ears. Bottom to top, ear 1 to 5 of Table 3-1 (see for details) and with data also attached to ears. (See Fig. 3-19 and text.) Photo © H. H. Iltis, 2005.

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FIGURE 3-19 Polystichy in ears of sweet corn. Bottom to top, ears 7, 6, 5 and 2 of Table 3-1. Nodes are marked with number of husks. Note in ear 7, the lowest 5 (or 6?) husks are solitary, distichous and face alternately left or right. Note slanting of nodes in ear 4, 5 and others, indicating incipient fusion (e.g., ear 2 [at top]), where the uppermost solitary husk was attached to a node that has half disappeared; the same in ear 5 (second ear from top), where the middlemost node is slanted. The great irregularity in the nodes is a reflection of increased condensation, the engine that fuels polystichy. Keep in mind that in the maize ear shank, due to a gradient in its condensation, there is a gradient from the primitive, distichous, alternate, teosintoid phyllotaxy of the husks in the first 1 to 5 nodes of the shank; grading more or less gradually to a decussate, tricussate phyllotaxy in the middle and shorter internodes of the shank; to very short internodes with a tri-cussate, quadri-cussate, or even penta-cussate, maizoid phyllotaxy at the crowded apex of the shank, one that by meristematic transfer somehow translates itself into the polystichy of the maize ear. Here, now truly, in the 6 to 30 cm or more of a shank, and with my compliments to Ernst Haeckel, fighter for the acceptance of evolution and Darwin’s German “bulldog,” ontogeny recapitulates maizoid phylogeny. Photo © H. H. Iltis, 2005.

Origin of Polystichy in Maize

ear’s apical meristem, this, one of the great stumbling blocks in other theories regarding the origin of polystichy. The happy accidental discovery of Stephens, [79] to be discussed next, verified my own findings and added additional insights, so that by now it is hard for me to separate my thoughts or words from his.

S. G. STEPHENS AND THE SHANK CONDENSATION THEORY—SHARPEYED, UNSUNG, UNCITED, AND UNEQUIVOCALLY CORRECT To emphasize its importance, I have saved a discussion of the only study that verified my own results until the end, one that added imaginative insights into the shank condensation gradient; namely, S. G. Stephens’ [79] study, one with a title so long that it would have scared anybody off (as it did me), and one that no doubt helped to condemn this fine paper to obscurity, never to be read, understood, or cited. Actually, it was cited once at least, the only time as far as I know, by Anderson’s student Norton Nickerson [73, p. 87], who quotes Stephens “that succeeding condensation proceeded acropetally once it was initiated, and that there would be a gradient of increasing condensation from the base to the apex of the main axis.” He thus understood Stephens’ main points fairly well, but mentions the husks only offhandedly and somewhat misses one of the main points, partly because, he says, Stephens is “not strictly in accord with the facts reported by Anderson [his ex-major professor] and Brown” [4]. Only 6 years after the publication of Stephens’ article, Anderson must have seen Nickerson’s manuscript and reviewed it, which may explain Nickerson’s ambivalence in properly appraising Stephens’ work. According to Stephens, at the time a postdoctoral student with the Department of Genetics of the Carnegie Institution of Washington at Cold Spring Harbor, Long Island, New York, the subject had been suggested by Edgar Anderson, and the mutant’s seeds supplied by none other than the acerbic, brilliant Barbara McClintock; but none of that helped to save it from obscurity. At the start, Stephens laid out his strategy that, to understand the inflorescences of maize, such an investigation should be based on Anderson’s [2] 1944 paper, and the realization that the structure of the inflorescence must be considered “as a culmination of developmental processes which are common to the plant as a whole, [because] a study of the inflorescence apart from the rest of the plant [e.g., the shank] might neglect a very valuable source of information.” Thus, from the developmental point of view, the morphology of the maize ear or tassel “represents the crux of the problem; namely, by what developmental process is the simple alternate (distichous) arrangement of primordia, as seen in the basal vegetative portion of the shoot, transformed into the

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polystichous arrangement found in the apical reproductive region” [79, p. 289, italics added]. Stephens’ experiments produced, as illustrated in his plate 33, abnormally long internodes alternating with highly condensed and crowded node clusters. These were ideal subjects to study node condensation or compression in the shanks and their relationship to their husks. Of the four shanks illustrated, two, (a) and (b), have greatly elongated internodes interrupted by zones of condensation of clustered, short internodes, and variously-angled nodes caused by experimentally induced abnormalities: Thus, Figure 33(a) illustrates “a main axis of a tassel ear . . . a portion of a tiller of a normal plant which bore a tassel partly modified towards femaleness (tassel ear)” [79, p. 295]. [A tiller is a basal lateral stem, sucker, or off-shoot from the main stem]. Figure 33(b) is a “female axillary branch induced to develop by tassel extirpation below the usual ear-bearing nodes.” The remaining figures, (c) and (d), are of two normal shanks; namely, “axillary branches [i.e., shanks] bearing normal ears on abnormally [sic; this surely a mistake] long shanks.” Then the legend continues: “In all cases at nodes below the condensed region, [husks] were borne singly, while nodes [within] the condensed region bore two or more [husks] each” (italics added). Summarizing the pictures of the four shanks, Stephens emphasizes that below the condensed regions each node bore only one husk, whereas within the condensed region, “more [husks] than visible nodes were always present. This condition would seem to be true for normal ear-bearing branches in general, since careful examination shows that the number of husks enclosing the ear is always greater than the number of distinct ridges [nodes] on which they are borne” [79, p. 295]. This, the first of several important conclusions, is crucial in its universal application. The statement that follows is an understatement that would make any Englishman proud: “It seems to the writer that the association of ear structure with a region of condensed shank nodes immediately below it may be of developmental significance.” Noting next that condensation begins with a twisting of the axis, and that as a consequence, the tilted node tends to fuse with the node immediately below, “the series of separate [nodes] becomes converted into a continuous helical [node]. Future twisting results in a suppression of the internode between the gyres and a consequent fusion of neighboring gyres . . . [which, in turn results in] multiplication of axillary structures [husks] and axillary buds [on each of the compounded nodes. With polystichy due to] condensation initiated in the shank, [it] would [thus be] continued and intensified in the ear [and tassel] itself.” And finally, after these momentous, brilliant insights, Stephens gives to his mentor Anderson the gift of explaining Anderson’s own research: “Furthermore, this interpretation appears to be the simplest way of explaining the

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correlation between degree of tassel condensation and ear row number which has been demonstrated by Anderson (1944)” [79, p. 296]. That Anderson, to my knowledge, never appreciated Stephens’ work or ever cited it as far as I know, and, in fact, when one of his students, Nickerson [73] did cite it, indirectly undercut its acceptance because it conflicted with his own work, demonstrates as well as anything how radical a notion Stephens presented and how unprepared his scientific colleagues and even teachers were to accept it and what a remarkable intellectual achievement his paper represents.

POSTSCRIPT My search to make sense of polystichy in the maize ear and its genesis has now reached an end. From trying to verify Collins’ theory of decussation, dissecting untold numbers of shanks and husks to correct someone’s erroneous assumptions, and focusing on this all-but-ignored, unstudied, and yet crucial structure, rather than on the same overdescribed and often misunderstood ear, came many an

insight into maize morphology, but no satisfactory resolution. As far as I knew, my interpretations of shank peculiarities fizzled out in an unsatisfactory, ambiguous conclusion (that was exactly backward, as it turned out). That my mistake was explained within an overly long, two-page footnote, of which nobody took note, was just as well. And yet, in preparation for the present chapter, after dissecting more shanks and husks, after reading more papers and coming out empty-handed, the hard work led early one recent morning to a moment of truth, a true epiphany, when the realization all at once dawned on me that polystichy could not possibly have been generated by the ear’s apical meristem and then somehow, as I used to think, penetrate the upper nodes of the shank. Rather, exactly the reverse is true: it is generated through condensation twisting that leads to fusion of the upper nodes of the shank, with the resulting polystichous phyllotaxy of the husks then expressing itself in the butt of the ear as a template for the polystichous arrangement of its grains. But, then, several months later, I came across an obscure, never-cited short paper; one I previously had always skipped over because of its unending, 21-word–long title and its

FIGURE 3-20 Maize “seed corn” ears, sorted by colors, that I was told indicate the number of months to harvest time (“quatro mes . . . / . . . siete mes . . .”), and hung from the second floor rafters of a small, weathered, palm-thatched two-room casita, ca. two km from San Antonia Huista on the road to Santa Ana Huista, Huehuetenango, Guatemala, an unsung treasury of maize “germoplasmo,” that year by year, region by region, is steadily passing into oblivion. January 9, 1976. Photo © H.H. Iltis, 2005. Also appears in color insert.

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FIGURE 3-21 The leitmotiv to the origin and domestication of maize— toward ever-greater apical dominance with ever-greater condensation in ever-fewer ears, culminating in the polystichous apically dominant terminal ears of maize. Understanding the basic bilateral dorsiventrality of the Zea plant is the architectural key to the understanding of maize domestication. Design by Kandis Elliott.

subject matter (“a dwarf mutant in maize”) by one S. G. Stephens, who, to my wide-eyed astonishment, joy, and deep satisfaction (and not a little disappointment on being partially “scooped” 57 years ago) gave splendid verification to my “new, unique” theory of how and why distichy in the stem gave rise to polystichy, not in the ear, but in the shank, and how in the shank the nodes on which the husk are carried coalesced by “twisting” to create from the teosintoid distichy at the base the maizoid polystichy at the top. So it seems that Collins was not all that wrong after all with his twisting, but it came earlier in ontogeny, and in the shank, and not in the ear or tassel. Published in 1948 in the Annals of the Missouri Botanical Garden only two months after I entered that venerable old institution as a graduate student, and in a report on the 1947 Conference on “The Inflorescence of Zea mays,” probably edited by none other than Edgar Anderson (who within a few months became my most influential professor), Stephens’ classic paper remains unknown and unsung to this day. But not for long. And who was Stephens? It turns out, as a young postdoctoral student at Carnegie’s Cold Spring Harbor Lab, he did this work at Anderson’s suggestion on a mutant given to him by Barbara McClintock, and then went on to Texas and North Carolina to become one of the greatest ethnobotanical researchers on the contentious origins of cotton. And, yet, there are still questions begging for answers: How does polystichy transfer from shank to ear and from husk to grain? Does each initial alicole (spikelet pair) come from a hidden meristem axillary in each of the topmost husks? And then does it self-duplicate, just as a copy machine, to create the awesome symmetry shown in Sundberg and Orr’s fantastic SEM photos [80–83] and in the maize ear itself, as Stephens, citing D’Arcy Thompson’s laws of organized development, evidently thought?

FIGURE 3-22 Xilonen, early maize ear goddess. “On the first day of the eighth month the day of Xilonen, goddess of early ears, was celebrated. That day people gave food to the poor, young and old, men and women. After honoring Xilonen, all had the right to eat xilotes—early ears—and bread made of xilotes and to eat maize canes. Before honoring Xilonen, nobody did so.” Text with clay effigy of Xilonen, goddess of Early Maize, a Zapotecan Funerary Urn, at the Centro Internacional de Mejoramente de Maíz y Trigo [CIMMYT] maize museum, El Batáan, Texcoco, Mexico. October 1980. Photo © H. H. Iltis, 1980.

And, lastly, how, in this terrible and destructive age, are we to conserve the kaleidoscopic biodiversity of the 400 or so Latin American landraces of maize and the dwindling populations of wild teosinte in Mexico and Central America [53, 12, 92] before blind biotechnology and the human population explosion drives them into irreversible extinction? [50, 56, 58, 72]. That is the truly big question.

Acknowledgments To my former students, John Doebley for lending me a specimen of the Tga 1 mutated teosinte, and especially Bruce Benz for his critical interest in the problems of domestication, and both for their published ideas and many personal favors. To Kandis Elliot, who for many years improved my illustrations and drew and redrew new ones with her talented computer, and to Claudia Lipke’s super photographs of the mutated teosinte, to both many thanks; and finally, to my life’s companion, Sharyn Wisniewski, who under editorial pressure and out of personal goodness, typed and retyped the— always final—versions with good cheer, my deepest appreciation.

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Origin of Polystichy in Maize 50. E. Hoyt. (1988). Conserving the wild relatives of crops. Rome: International Board for Plant Genetic Resources. 51. H. Iltis. (1991). Über einige bei Zea mays L. beobachtete Atavismen, ihre Verursachung durch den Maisbrand Ustilago maydis D.C. (Corda), und über die Stellung der Gattung Zea im System. Zeitschrift für Induktive Abstammungs und Vererbungslehre, 5(1), 38–57. 52. H. H. Iltis. (1971). The maize mystique—A reappraisal of the origin of corn. Madison, WI: Botany Department of University of Wisconsin–Madison. 53. H. H. Iltis. (1974). Freezing the genetic landscape: The preservation of diversity in cultivated plants as an urgent social responsibility of plant geneticist and plant taxonomist. Maize Genetics Cooperation Newsletter, 48, 199–200a. 54. H. H. Iltis, (1983). From teosinte to maize: The catastrophic sexual transmutation. Science, 222, 886–894. 55. H. H. Iltis. (1987). Maize evolution and agricultural origins. In: T. R. Soderstrom, K. W. Hilu, C. S. Campbell, M. E. Barkworth, (Eds.), Grass systematics and evolution. Washington, D.C.: Smithsonian Institution Press. pp. 195–213. 56. H. H. Iltis. (1988). Serendipity in the exploration of biodiversity: What good are weedy tomatoes? In: E. O. Wilson, (Ed.) Biodiversity. Washington, D.C.: National Academy Press. pp. 98–105. 57. H. H. Iltis. (2000). Homeotic sexual translocation and the origins of maize (Zea mays, Poacaea): A new look at an old problem. Economic Botany, 54(1), 7–42. 58. H. H. Iltis. (2002). The impossible race: Population growth and the fallacy of agricultural hope. In: A. Kimbrell, (Ed.), The tragedy of industrial agriculture. San Francisco: Island Press. pp. 35–39. 59. H. H. Iltis. (2004). Domestication of Zea: First for sugar and then for grain? A novel idea with vast implications. Paper presented at the 69th Annual Meeting of the Society for American Archaeology, Montreal, Canada, March 31–April 4, 2004. 60. H. H. Iltis, J. F. Doebley. (1980). Taxonomy of Zea (Gramineae). II. Sub-specific categories in the Zea mays complex and a generic synopsis. American Journal of Botany, 67, 994–1004. 61. H. Jacques–Feliz. (1957). Sur une interpretation nouvelle de l’embryon des Graminées. Comptes Rendues de l’Academie des Sciences [Paris] Series D, 245, 1260–1263. 62. S. H. Katz, M. L. Heddiger, L. A. Vallery. (1974). Traditional maize processing techniques in the New World. Science, 184, 765–773. 63. T. A. Kiesselbach. (1949/1980). The structure and reproduction of corn. Lincoln: University of Nebraska Press. 64. M. Lieberman, D. Lieberman. (1980). The origin of gardening as an extension of infra-human dispersal. Biotropica, 12(4), 316. 65. J. L. Lorenzo, L. Gonzalez Q. (1970). In El más Antiguo Teosinte. Boletín del Instituto Nacional de Anthropología e Historia [Mexico, D. F.], 40, 41. 66. P. C. Mangelsdorf. (1958). Ancestor of corn. A genetic reconstruction yields clues to the nature of the extinct wild ancestor. Science, 128, 1313–1320. 67. P. C. Mangelsdorf. (1974). Corn: Its origin, evolution and improvement. Cambridge, MA: Belknap Press of Harvard University Press. 68. P. C. Mangelsdorf, R. G. Reeves. (1939). The origin of Indian corn and its relatives. Texas Agricultural Experiment Station Bulletin, 574, 1–315. 69. Y. Matsuoka, Y. Vigouroux, M. M. Goodman, J. Sanchez, E. S. Buckler, J. F. Doebley. (2002). A single domestication for maize shown by multilocus microsatellite genotyping. Proceedings of the National Academy of Sciences of the United States of America, 99, 6080– 6084.

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70. E. G. Montgomery. (1906). What is an ear of corn? Popular Scientific Monthly, 68, 55–62. 71. E. G. Montgomery. (1913/1916). The corn crops. New York: MacMillan Co. 72. N. Myers. (1979). The sinking ark. A new look at the problem of disappearing species. Oxford, UK: Pergamon Press. 73. N. H. Nickerson. (1954). Morphological analysis of the maize ear. American Journal of Botany, 41, 87–92. 74. D. R. Piperno, K. V. Flannery. (2001). The earliest archaeological maize (Zea mays) from highland Mexico: New accelerator mass spectrometry dates and their implications. Proceedings of the National Academy of Sciences of the United States of America, 98, 2101–2103. 75. L. M. Roberts, U. J. Grant, R. Ramirez, W. H. Hatheway, D. L. Smith, in collaboration with P. C. Mangelsdorf. (1957). Races of maize in Colombia. Washington, D. C.: National Academy of Sciences, National Research Council. 76. K. Schumann. (1904). Mais und teosinte, In: I. Urban, P. Graebner (Eds.), Festschrift fur Paul Ascherson. Leipzig, Germany. pp. 137–157. 77. B. C. Sharman. (1942). Developmental anatomy of the shoot of Zea mays L. Annals of Botany, New Series, 4(22), 245–282. 78. J. Smalley, M. Blake, (Eds.). (2003). Sweet beginnings. Stalk sugar and the domestication of maize. Current Anthropology, 44, 675–703. 79. S. G. Stephens. (1948). A comparative developmental study of a dwarf mutant in maize, and its bearing on the interpretation of tassel and ear structure. Annals of the Missouri Botanical Garden, 35, 289–299. 80. M. D. Sundberg, J. F. N. Doebley. (1990). Developmental basis for the origin of polystichy in maize. Maize Genetics Cooperation Newsletter, 64, 21–22. 81. M. D. Sundberg, C. La. Fargue, D. A. Orr. (1995). Infloresence development in the “standard exotic” maize, Argentine popcorn (Poaceae). American Journal of Botany, 82, 64–74. 82. M. D. Sundberg, A. R. Orr. (1990). Inflorescence development in two annual teosintes: Zea mays ssp. mexicana and Z. mays ss. parviglumis. American Journal of Botany, 77, 141–152. 83. M. D. Sundberg, A. R. Orr. (1996). Early inflorescence and floral development in Zea mays land race Chapalote (Poaceae). American Journal of Botany, 83, 1255–1265. 84. H. H. Wang, T. Nussbaum-Wagler, B. Li, Q. Zhao, Y. Vigouroux, M. Faller, K. Bomblies, L. Lukens, J. F. Doebley. (2005). The origin of the naked grains of maize. Nature, 436, 714–719. 85. P. Weatherwax. (1918). The evolution of maize. Bulletin of the Torrey Botanical Club, 45, 309–342. 86. P. Weatherwax. (1923). The story of the maize plant. Chicago: University of Chicago Press. 87. P. Weatherwax. (1935). The phylogeny of Zea mays. American Midland Naturalist, 16, 1–71. 88. P. Weatherwax. (1948). Right–handed and left–handed corn embryos. Annals of the Missouri Botanical Garden, 35, 317–321. 89. D. Webster, D. Rue, A. Traverse. (2005). Early Zea cultivation in Honduras: Implications for the Iltis hypothesis. Economic Botany, 59, 101–111. 90. E. J. Wellhausen, L. M. Roberts, E. Hernandez, in collaboration with P. C. Mangelsdorf. (1952). Races of maize in Mexico. Cambridge, MA: Bussey Institution, Harvard University Press. 91. H. G. Wilkes. (1967). Teosinte: The closest relative of maize. Cambridge, MA: Bussey Institution, Harvard University Press. 92. H. G. Wilkes. (1985). Teosinte: The closest relative of maize revisited. Maydica, 30, 209–223. 93. D. Zohary, Unconscious selection and the evolution of domesticated plants. Economic Botany, 58, 5–10.

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4 Dating the Initial Spread of Zea mays MICHAEL BLAKE Department of Anthropology and Sociology, University of British Columbia, Vancouver, British Columbia, Canada

Introduction 55 Temporal Frameworks for Zea mays’ Early Dispersal 56 Direct Dating of Maize 57 On the Indirect Dating of Maize 59 Dating the Early Distribution of Zea Pollen 60 Dating the Early Distribution of Maize Phytoliths 63 Dating the Early Distribution of Moderate-to-High Stable Carbon Isotope Ratios 65 Comparing the Different Lines of Evidence 68 Discussion of the Social Implications of Maize’s Early Spread: Initial Uses of Maize 68

that minimizes the statistical error of estimation by using a set of known data points near the point to be estimated. New studies of Zea mays genetics suggest that all modern maize evolved from teosinte (Zea mays ssp. parviglumis), originating in the Río Balsas drainage of western Mexico. The processes whereby early occupants of the region interacted with teosinte; harvested its seeds, leaves, and stalks; and eventually transported or traded the plant and its descendants far beyond its natural range are not yet clearly understood. This chapter traces the spatial and chronological radiation of maize and all current archaeological and paleoethnobotanical evidence of early Zea mays from Mesoamerica, Central America, and South America, demonstrating that social uses of the plants’ many products, including sugar, could have been as important in its early spread as were its nutritional uses.

Glossary AMS dating A radiocarbon dating technique using accelerator mass spectrometry that requires only minute samples of ancient material to directly count the amount of 14C remaining. Bioturbation Disturbance to the layers of archaeological deposits, and the materials contained within them, caused by biological organisms such as earthworms, beetles, and rodents. Bioturbation can result in older materials being found in younger layers and vice versa. Coprolites Preserved feces, often found in dry cave sites, that contain food residues and other materials, including pathogens, and can help in identifying ancient subsistence patterns and health. Isoclines A set of lines drawn on maps to indicate regions of similar value; for example, elevations (contours), precipitation, temperature, age, and population density. Kriging A method used for interpolating or predicting values, such as elevations and so forth, for a spatial data set when only a limited number of known measurements is available. The kriging formula uses a variogram model

Histories of Maize

INTRODUCTION Two important discoveries have helped to reframe our understanding of Zea’s domestication and early spread. The first is the accumulating genetic evidence that maize (Zea mays ssp. mays) arose from an annual teosinte (Zea mays ssp. parviglumis), whose present-day range is centered in the Río Balsas region of western Mexico [50, 101], but extends west to Jalisco and southeast to Oaxaca [31]. The second is the direct accelerated mass spectrometry (AMS) radiocarbon dating of exceedingly small fragments of maize, establishing a reliable, absolute chronology for its initial appearance and eventual dispersal. Bruce Smith [87] has recently observed, these two lines of biological and archaeological evidence are providing scholars with exciting new approaches to their research on the questions of when, why,

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and how maize spread out of its homeland to new regions far beyond its zone of initial domestication. Other important questions include what were the ways in which the first maize cultivators used the plant and how did these initial uses lead to its distribution throughout the Americas? These are key questions because they highlight the selective forces that cumulatively shaped the genetic transformation of teosinte from a localized western Mexican wild grass to the world’s number one food crop. As with most domesticates, these forces were primarily social ones. They resulted from the active decisions of countless people who used the plant for many different purposes, ranging from food and drink to building materials, for thousands of years. Many of maize’s uses may have been more important in the past than they are today, and many of today’s uses are much more varied and elaborate than they were in the past. These long-term shifts in the characteristics and potential uses of maize suggest that its social significance must also have changed, both within its original homeland and in the new regions where it was eventually adopted. Definitive answers to these questions are not yet possible—mainly because we know so little about early maize distribution. Besides the well-known examples from several dry caves in three separate regions (Tamaulipas, Tehuacán, and Oaxaca), as pointed out by Smith [87, p. 1325], few macrobotanical samples of maize have been recovered from Pre-Ceramic sites in Mexico. The only directly dated maize remains (using AMS radiocarbon dating) from Pre-Ceramic contexts are restricted to 12 samples from the Tehuacán caves [48], 6 from the Ocampo Caves in Tamaulipas, [44, 85, pp. 373–374] and 2 from Guilá Naquitz in Oaxaca [66]. Despite this small number of directly dated specimens, it has been possible for researchers to detect trajectories of morphological and genetic changes in assemblages of maize cobs from these sites and conclude that Pre-Ceramic peoples were intentionally selecting for several characteristics. Benz and Long [6, p. 463], in their study of Tehuacán maize, suggest that before 2500 BC (ca. 4450 BP) humans were initially interested in selecting maize ears with more kernels; and only later did they select ears with larger kernel sizes. After 2500 BC the rate of change in ear morphology slowed, and people were possibly more concerned with increasing the number of ears per plant. Genetic analysis of maize from the Ocampo caves indicates people were selecting for increased protein and starch quality, and that some specimens were similar to modern maize by 4450 BP (ca. 2500 BC) [44, p. 1207]. Jaenicke-Després and her colleagues [44] also discovered, however, that as recently as 2000 BP maize from New Mexico still had an allele of the gene sugary-1 (su1) in common with teosinte; and that probably prevented it from producing the high-quality starch found in modern maize—a trait that, for example, gives maize starch the sticky consistency necessary in making tortillas.

One factor that has made it difficult to answer questions about the spread of maize is that the direct AMS dating of Pre-Ceramic maize in the United States, and to a lesser extent in Mexico, is not matched by similar developments to the south. Instead, almost all of the indications of Pre-Ceramic maize south and east of Oaxaca and into Central and South America come from two types of microbotanical remains: pollen and phytoliths. These types of remains have generally been recovered from cores in lakes and swamps, and sometimes cave deposits, and have been dated indirectly by association with charcoal or other organic materials also recovered from the cores or caves. Researchers have relied on these assemblages of microscopic phytoliths and pollen to determine the presence or absence of maize in this vast region, because Pre-Ceramic caves and open-air sites are both rare and have yielded few dateable maize macroremains. Here, I summarize the current studies of directly dated maize macrobotanical remains, map their distribution in the Americas, and compare these data with studies of indirectly dated maize microbotanical remains. The purpose of this comparison is to determine the extent to which these different views of maize tell us similar or differing stories about maize’s initial spread. During the past few years it has become clear that directly dated macrobotanical remains have yielded significantly younger dates than indirectly dated microbotanical remains. What are the implications of these discrepancies and how might they influence our models of the origins of maize agriculture? To make an initial attempt at answering these questions, I first map maize’s spread using the earliest directly dated maize macrobotanical remains in each region where samples exist and then map maize microbotanical remains by age, to show how these data provide a different picture of the spread of maize. Finally, I map the age distribution of stable carbon isotope values of human bone samples indicating a significant consumption of maize in the diet. These maps are meant to summarize our current knowledge of maize’s distribution and fill in the details that are suggested by earlier maps, such as Peter Bellwood’s [3, p. 147] excellent recent summary.

TEMPORAL FRAMEWORKS FOR ZEA MAYS’ EARLY DISPERSAL To understand the spread of maize it is necessary to accurately map its first occurrence in every region of the Americas. The two main methods for dating maize macrobotanical remains have been: (1) indirect dating, that is, by association with organic remains such as wood charcoal in archaeological deposits, and (2) the direct dating of maize macroremains using AMS radiocarbon dating (and occasionally conventional dating). Here, I concentrate on direct AMS dates using maize macroremains because indirect dates have often proven to be unreliable. Although individ-

Dating the Initial Spread of Zea mays

ual indirect dates may be correct in some cases (that is, truly associated with a given maize sample, as Smith [85] has shown for some of the Ocampo cobs), in many other cases they are not. As noted by Long and colleagues [48] for the Tehuacán maize, it is common for more recent macrobotanical remains to work their way downward, as a result of both natural and cultural disturbances, into earlier deposits and thereby be incorrectly associated with older organic materials (in Chapter 29, Rivera describes this problem for several Chilean sites, and Smith [88] documents the vertical movement of AMS dated cucurbit remains from deposits at Coxcatlán Cave).

DIRECT DATING OF MAIZE Table 4-1 presents the directly dated samples of maize used in this analysis. This is not a complete list of all directly dated maize in the Americas. Instead, I have included only the earliest sample from each site (or cluster of sites in a region), omitting later examples that will not shed additional light on the question of the initial spread of maize. So, for example, at Romero’s Cave in Tamaulipas, Mexico, I include the earlier of two dates on maize cobs from that cave. Unless otherwise noted, all dates are presented in uncalibrated radiocarbon (14C) years BP. Table 4-1 includes the radiocarbon sample’s laboratory identification number where available, as well as the published source of the data. The dates were then plotted on a map of the Americas using Surfer 8.0, a commercially available and widely used program. Surfer allows the dates to be plotted as isoclines, representing interpolated age ranges, and calculated using the program’s various grid interpolation algorithms. For the maps produced here, I have gridded the data using Surfer’s kriging algorithm. Figure 4-1 shows the distribution of the 30 direct dates (predominantly AMS) recorded for the earliest occurrences of macrobotanical maize remains. The isoclines, or “age contours,” are set at 500-year intervals and show the broad trends of dispersal based solely on known, dated specimens. As Bruce Smith [85] pointed out, there are huge gaps in our regional coverage, and a great deal more needs to be done to both date existing collections and to recover more samples from known contexts. The distribution of sites in Mesoamerica and North America, in Figure 4-1, shows a clear “hot spot” resulting from the earliest AMS dates from Guilá Naquitz Cave in Oaxaca (5420 ± 60 BP [Beta-132511], [66]) and San Marcos Cave in the Tehuacán Valley (4700 ± 110 BP [AA-3311], [48]). Radiating out from this is a series of successively younger maize dates with only a few from southern Mesoamerica and the bulk from northern Mexico and the American Southwest. This pattern suggests that maize

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spread rather slowly northward to Tamaulipas (Romero’s Cave [3930 ± 50 BP, Beta-85431], [85]) and later to Chihuahua (Cerro Juanaqueña [2980 ± 50 BP, INS-3983], [35]). From northern Mexico, maize was brought into the American Southwest by about 3000 radiocarbon years ago (e.g., Fresnel Shelter, New Mexico [2945 ± 55 BP, AA-6402], [93]). By 1500 to 2000 BP, maize spread out of the American Southwest and northeast into the major tributaries of the Mississippi River (e.g., the Holding Site, near Cahokia, Illinois [2077 ± 70 BP, AA-8717], [72]). The genetic characteristics of maize in the American Northeast are most similar to southwestern maize, suggesting a direct link between the two regions [50]. In Mesoamerica, the next earliest maize, after the Tamaulipas samples, comes from Chiapas, Mexico. Seven AMS dates have been made on maize from a cluster of sites in the Mazatán region along the Pacific Coast [8, 20]. The youngest of these comes from Aquiles Serdán (3000 ± 65 BP [Beta-62920], [20]) and the earliest is from the site of San Carlos (3365 ± 55 BP [Beta-62911], [20]). The only other directly dated maize samples in Mesoamerica are even later than the ones from the American Southwest. One cob fragment comes from San Andrés in Tabasco (2565 ± 45 BP [AA-33923], [70]) and another from El Gigante rock shelter in Honduras (2280 ± 40 BP [Beta-159055], [78]). It is surprising that no other early context (either PreCeramic or Early Formative) maize samples have yet been directly dated in Mesoamerica or Central America. One site in the Arenal Reservoir region of Costa Rica is reported to have a maize kernel in association with wood charcoal that has been conventionally dated to 4450 ± 70 [10, 80]. However, we must be cautious in accepting this date as an indication of early maize cultivation until the kernel itself can be directly dated using AMS. In South America (Figure 4-1) there have been few directly dated maize macrobotanical remains. Unfortunately, as with most of Central America, there are not yet any AMSdated samples of early maize from Colombia or Peru. There are, however, seven directly dated samples from Ecuador, Chile, and Argentina. The two earliest samples come from the Ramaditas site in Chile (2210 ± 55 [GX-21725], Chapter 29), and Gruta del Indio in Argentina (2065 ± 40 [GrN-5396] a conventional date [32]). Gil [32] also reports four more recent AMS dates on maize from several sites in the southern Mendoza region, not far from Gruta del Indio (these range from 740 BP ± 40 BP to 1045 ± 45 BP). Also included in Figure 4-1 is the AMS-dated sample from the Loma Alta site in coastal Ecuador [59, p. 223]. The actual date has not yet been published, but the maize sample is thought to be associated with deposits dated to 3500 BP (or later). This pattern for South America is surprising given the microbotanical evidence (discussed later) for the presence of maize in Central and South America at early dates. Early maize macroremains in the zone from 12° north latitude to

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TABLE 4-1 Country/Region

Dated material

United States New Mexico New Mexico New Mexico Arizona Arizona Arizona Arizona Arizona New Mexico New Mexico New Mexico Illinois New Mexico Tennessee Ohio

Tornillo Shelter Bat Cave Fresnal Shelter Milagro Three Fir Shelter Fairbank Cortaro Fan West End LA18091 Jemez Sheep Camp Shelter Holding (Cahokia) Tularosa Cave Icehouse Bottom Harness Mound

maize cobs (8 pooled) maize maize maize maize maize maize maize maize maize maize maize cob maize cob maize maize

Mexico Oaxaca Puebla Tamaulipas Tamaulipas Chiapas Sonora Chihuahua Tabasco

Guilá Naquitz San Marcos Cave Romero’s Cave Valenzuela’s Cave San Carlos La Playa Cerro Juanaqueña San Andres

Honduras Inland Ecuador Coastal Peru Coast Argentina Mendoza Chile North coast

14

C Method

Radiocarbon years BP

Sample ID number

Reference

Conventional AMS AMS AMS AMS AMS AMS AMS AMS AMS AMS AMS AMS AMS AMS

3175 ± 240 3010 ± 150 2945 ± 55 2930 ± 45 2880 ± 140 2815 ± 80 2790 ± 60 2735 ± 75 2720 ± 265 2410 ± 360 2290 ± 210 2077 ± 70 1920 ± 40 1775 ± 100 1730 ± 85

maize cob maize cob maize cob maize cob kernel maize maize cob maize cob

AMS AMS AMS AMS AMS AMS AMS AMS

5420 ± 60 4700 ± 110 3930 ± 50 3890 ± 60 3365 ± 55 3000 ± ? 2980 ± 50 2565 ± 45

Beta-132511 AA-3311 Beta-85431 Beta-85433 Beta-62911 INS-3983 AA-33923

[66, p. 2102] [48, p. 1037] [85, p. 373] [85, p. 374] [20; 8, p.164] [49, p. 345] [35, p. 1664] [70, p. 1372]

El Gigante

maize cob

AMS

2280 ± 40

Beta-159055

[78]

Loma Alta

kernels

AMS

3340 ± 60

I-4405 Beta-18198

[54, p.134] [77, p. 103; 76, p. 187]

Conventional

cob impressions

2928 ± 105

Y-1150

[22, pp. 68–72]

Conventional

Kernel

4450 ± 70

n/a

[10, 80]

Kernels

ca. 2550

phase

[73, p. 235; 60, p. 334]

990 ± 60

n/a

[30]

ca. 3150

n/a

[47, p. 118]

>2640 ca. 3500

n/a n/a

[59, pp. 230–231] [59, p. 232]

ca. 3000

n/a

[59, p. 232]

2190 ± 210

ISGS-510

[14, p. 254]

one Urabarriu (B2-b)

3130 ± 80 2990 ± 75 6070 ± 70

TX-4446 UGA-4526 GIF-6772

[34, p. 69; 89, p. 126] [71, pp. 10, 30] [9, p. 839]

phase endpoint Early Horizon

27 14C dates several dates GX-5076

[15, p. 277]

phase midpoint 1150–800 BC Late Middle Period

Guatemala 50 cob impressions, Cuadros Phase, 1000–900 BC

Costa Rica

Brazil Minas Gerais Ecuador Coastal

Peru Inland

Inland Casma

Conventional cobs cob fragments and kernels cob fragments and kernels cob fragments and kernels two kernels (earliest one is from unit B2) single cob at site maize unidentified unidentified

2925 ca. 3820 4140 ± 160

Chapter 28

phase midpoint 800–400 BC

Dating the Initial Spread of Zea mays

Venezuela Amazonia

[9, p. 838]

61

62

TABLE 4-3 Country/Region Mexico Oaxaca

Site name

Dated material

Dates on Materials Associated with Zea Pollen Samples 14

C Method

Associated Zea

Radiocarbon years BP

Sample ID number

Reference

8240

estimated midpoint between ca. 9500– 6980 14C years BP. AA38771 I-4405 CAMS-1770

[79, p. 229; 66, p. 2102]

[70, p. 1372] [54, pp. 132–137] [33, pp. 84–86]

not given

[52, 53]

Guilá Naquitz

organic materials

Conventional

pollen (teosinte)

San Andrés Zoapilco Laguna Pompal

wood n/a pollen residue

AMS Conventional AMS

pollen pollen pollen

6208 ± 47 5090 ± 115 4250 ± 70

Guatemala Pacific coast

Sipacate

wood

AMS

pollen

4600

Belize Caribbean coast

Cob Swamp

wood

Conventional

pollen

4610 ± 60

Beta-56775

[69, pp. 360–361]

Lake Yojoa

wood

Conventional

pollen

expected D = 0.17158). The maximum pairwise deviation was in the percentage of 10-rowed cobs. Collectively, these data suggest that there is a shift through time from the San Pedro phase through the Cienega phase toward higher row number. Included with the phase level samples is the Basketmaker II assemblage from Three Fir Shelter. Row number distribution is virtually identical with that of the spatially distant Cienega sites, some of which are roughly 500 km to the south. To evaluate the similarity between the Cienega sites and Three Fir Shelter, a Kolmogorov-Smirnov twosample test was used. At a probability of 0.01, the test determined that there were no significant differences between the two samples (observed D = 0.048, ∂15N(‰)

Modern/ archaeological

Habitat

fish

mojarra negra

mojarra

Chiclasoma sp.

Barra San Jose

−26.7

6.7

modern

estuary

fish

peje gallo robato??

unidentified

unidentified

Barra San Jose

−22.3

10.4

modern

estuary

fish

vieja

spotted sleeper

Eleotris picta

Puerto Madero

−28.2

4.9

modern

estuary

11.9

modern

marine

fish

calamar dardo

dart squid

Loliolopsis diomedeae

Puerto Madero

−16.6

fish

calandria

steeplined drum

Larimus acclivis

Puerto Madero

−15.7

fish

chacalin, camaroncillo

Pacific seabob

Xiphopenaeus riveti

Puerto Madero

−13.9

fish

chivo

goatfish

Pseudupeneus squamipinnis

Barra San Jose

−14.1

modern

marine

10.2

modern

marine

16.0

modern

marine

fish

cocinero

bigeye scad

Selar crumenophthalmus

Barra San Jose

−16.1

12.0

modern

marine

fish

corvina

silver weakfish

Isopisthus remifer

Barra San Jose

−14.5

14.9

modern

marine

fish

huachinango

Pacific red snapper

Lutjanus peru

Puerto Madero

−28.7

8.7

modern

marine

fish

jurel

Pacific crevalle jack

Caranx caninus

Barra San Jose

−14.8

15.2

modern

marine marine

liza

white mullet

Mugil curema

Paredon

−12.4

10.3

modern

liza

white mullet

Mugil curema

Barra San Jose

−20.9

4.9

modern

marine

fish

mojarra

mojarra

Cichlasoma sp.

Rio Angostura??

−13.3

22.7

modern

marine

fish

pampano (jurel verde)

green jack

Caranx caballus

Barra San Jose

−16.3

11.8

modern

marine

fish

peje caite

unidentified

unidentified

Barra San Jose

−14.6

13.4

modern

marine

fish

peje gallo

elephantfish

Callorhinchus callorynchus

Paredon

−14.2

16.7

modern

marine

fish

pelona

Leatherjacket

Oligoplites saurus

Paredon

−13.0

10.0

modern

marine

fish

pelona

Leatherjacket

Oligoplites saurus

Barra San Jose

−13.5

14.8

modern

marine

fish

pez vela

sailfish

Istiophorus platypterus

Puerto Madero

−15.4

13.2

modern

marine

fish

pulpo

octopus

Octopus sp.

Rio Coatan

−13.7

9.7

modern

marine

fish

raton del mar

Goode croaker

Paralonchurus goodei

Barra San Jose

−14.2

15.5

modern

marine

fish

raya gavilán

spotted eagle ray

Aetobatus narinari

Paredon

−12.0

18.5

modern

marine

fish

raya gavilán

spotted eagle ray

Aetobatus narinari

Barra San Jose

−15.8

13.0

modern

marine

fish

robalo

black snook

Centropomus nigrescens

Gulf Coast

−24.9

12.3

modern

marine

fish

sambuco de mar

inshore sand perch

Diplectrum cf. pacificum

Barra San Jose

−15.0

13.7

modern

marine

fish

bagre

river catfish

unidentified

Rio Angostura

−29.4

18.0

modern

river

fish

chacalin, camaroncillo

Pacific seabob

Xiphopenaeus riveti

Rio Coatan

−16.8

8.7

modern

river

fish

sardina

Pacific piquitinga

Lile stolifera

Rio Coatan

−19.2

6.8

modern

river

fish water

chato

Pacific smalleye croaker

Nebris occidentalis

Barra San Jose

−14.0

13.9

modern

salt

fish water

chavelita

yellowfin jack

Hemicaranx leucurus

Barra San Jose

−14.6

13.9

modern

salt

mammal

ardillón

pocket gopher

Orthogeomys cuniculus

Aquiles Serdan, 1B/6

−21.1

archaeological

terrestrial

mammal

ardillón

pocket gopher

Orthogeomys cuniculus

Aquiles Serdan, 1B/6

−23.9

archaeological

terrestrial

mammal

ardillón

pocket gopher

Orthogeomys cuniculus

Aquiles Serdan, 1B/N8

−23.1

archaeological

terrestrial

B. Chisholm and M. Blake

fish fish

armadillo

armadillo

Dasypus novencinctus

Aquiles Serdan, 1B/10

−21.6

archaeological

terrestrial

mammal

armadillo

armadillo

Dasypus novencinctus

Aquiles Serdan, 1B/6

−20.7

archaeological

terrestrial

mammal

armadillo

armadillo

Dasypus novencinctus

Aquiles Serdan, 1B/N8

−22.6

archaeological

terrestrial

mammal

conejo

cottontail rabbit

Sylvilagus sp.

Aquiles Serdan, 1B/6

−20.0

archaeological

terrestrial

mammal

conejo

cottontail rabbit

Sylvilagus sp.

Aquiles Serdan, 1B/N8

−22.3

archaeological

terrestrial

mammal

jabali

collared peccary

Tayassu tajacu

Aquiles Serdan, 1B/6

−21.9

archaeological

terrestrial

mammal

perro

dog

Canis familiaris

Aquiles Serdan, 1B/6

−19.6

archaeological

terrestrial

mammal

perro

dog

Canis familiaris

Aquiles Serdan, 1B/N8

−19.7

archaeological

terrestrial

mammal

tlacuache

opossum

Didelphis marsupialis

Aquiles Serdan, 1B/6

−20.8

−2.8

archaeological

terrestrial

mammal

venado

white tail deer

Odocoileus virginianus

Aquiles Serdan, 1B/6

−20.1

6.4

archaeological

terrestrial

mammal

venado

white tail deer

Odocoileus virginianus

Aquiles Serdan, 1B/N8

−19.0

1.5

archaeological

terrestrial

mammal

nutria

nutria

Myocastor coypus

Pampa Cantilena

−25.9

8.0

modern

estuary

mammal

nutria

nutria

Myocastor coypus

Pampa Cantilena

−26.7

10.7

modern

estuary

mammal

borrego

sheep

Ovis aries

Tapachula

−16.4

5.9

modern

terrestrial

mammal

borrego

sheep

Ovis aries

Tapachula

−16.8

8.8

modern

terrestrial

mammal

conejo

cottontail rabbit

Sylvilagus sp.

Paso de la Amada

−20.8

4.3

modern

terrestrial

3.9

mammal

perro

dog

Canis familiaris

Paredon

−11.7

10.1

modern

terrestrial

mammal

perro

dog

Canis familiaris

Buenos Aires

−14.0

8.5

modern

terrestrial

mammal

tlacuache

opossum

Didelphis marsupialis

Buenos Aires

−19.9

8.9

modern

terrestrial

mammal

venado

white tail deer

Odocoileus virginianus

Pampa Cantilena

−25.1

5.3

modern

terrestrial

mammal

venado

white tail deer

Odocoileus virginianus

Pampa Cantilena

−24.1

10.7

modern

terrestrial

mammal

venado

white tail deer

Odocoileus virginianus

Buenos Aires

−22.2

4.5

modern

terrestrial

reptile

cocodrilo

crocodile

Crocodylus acutus

Aquiles Serdan, 1B/6

−18.8

6.8

archaeological

estuary

reptile

cocodrilo

crocodile

Crocodylus acutus

Aquiles Serdan, 1B/6

−20.1

5.4

archaeological

estuary

reptile

cocodrilo

crocodile

Crocodylus acutus

Aquiles Serdan, 1B/6

−20.5

−3.4

archaeological

estuary

reptile

cocodrilo

crocodile

Crocodylus acutus

−20.0

0.1

archaeological

estuary

reptile

masacuate

boa snake

Boa constrictor

Aquiles Serdan

−19.7

archaeological

estuary

reptile

masacuate

boa snake

Boa constrictor

Aquiles Serdan, 1B/6

−21.2

archaeological

estuary

reptile

masacuate

boa snake

Boa constrictor

Aquiles Serdan, 1B/6

−21.6

reptile

tortuga

pond slider turtle

Trachemys sp.

Aquiles Serdan, 1B/6

−20.8

reptile

tortuga

pond slider turtle

Trachemys sp.

Aquiles Serdan, 1B/6

−19.5

reptile

tortuga casquito

mud turtle

Kinosternon sp.

Aquiles Serdan, 1B/6

archaeological

estuary

1.4

archaeological

estuary

archaeological

estuary

−19.8

6.8

archaeological

estuary

2.0

archaeological

estuary

reptile

tortuga casquito

mud turtle

Kinosternon sp.

−20.2

reptile

tortuga casquito

mud turtle

Kinosternon sp.

−19.9

archaeological

estuary

reptile

tortuga casquito

mud turtle

Kinosternon sp.

−21.1

archaeological

estuary

reptile

iguana

iguana

Iguana iguana

−23.1

archaeological

terrestrial

Aquiles Serdan, 1B/6

iguana

iguana

Iguana iguana

−22.1

vibora

unidentified

unidentified

−21.9

−0.3

archaeological

terrestrial

archaeological

terrestrial

(Continued)

171

reptile reptile

Diet in Prehistoric Soconusco

mammal

Family

Spanish common name

English common name

Scientific name

172

APPENDIX 2

(continued) Sample provenience

∂13C(‰)

>∂15N(‰)

Modern/ archaeological

Habitat

reptile

cocodrilo

crocodile

Crocodylus acutus

Pampa Cantilena

−22.9

4.2

modern

estuary

reptile

cocodrilo

crocodile

Crocodylus acutus

Vivero

−23.7

3.3

modern

estuary

reptile

cocodrilo

crocodile

Crocodylus acutus

Tapachula

−26.9

6.5

modern

estuary

reptile

masacuate

boa snake

Boa constrictor

Buenos Aires

−19.1

7.9

modern

estuary

reptile

masacuate

boa snake

Boa constrictor

Tapachula

−23.4

9.3

modern

estuary

reptile

masacuate

boa constrictor

Boa constrictor

Tapachula

−16.5

11.5

modern

estuary

reptile

tortuga

pond slider turtle

Trachemys sp.

Pampa Cantilena

−26.6

5.7

modern

estuary

reptile

tortuga

pond slider turtle

Trachemys sp.

Mazatan

−27.7

4.9

modern

estuary

reptile

tortuga casquito

turtle

Pampa Cantilena

−23.2

5.3

modern

estuary

tortuga casquito

mud turtle

Kinosternon sp.

San Lorenzo

−25.9

5.9

modern

estuary

tortuga casquito

mud turtle

Kinosternon sp.

Paredon

−16.9

6.4

modern

estuary

reptile

parlama

green sea turtle

Chelonia mydas

Barra

−14.7

12.6

modern

marine

reptile

tortuga

pond slider turtle

Trachemys sp.

San Lorenzo

−26.4

9.9

modern

river

reptile

cascabel

rattle snake

Crotalus durissus ssp.

Tapachula

−22.0

10.2

modern

terrestrial

reptile

cascabel

rattle snake

Crotalus durissus ssp.

Tapachula

−20.1

7.4

modern

terrestrial

reptile

iguana

iguana

Iguana iguana

Mazatan

−25.7

2.3

modern

terrestrial

reptile

iguana

iguana

Iguana iguana

Tapachula

−24.4

4.3

modern

terrestrial

reptile

iguana

iguana

Iguana iguana

Soconusco

−21.6

14.9

modern

terrestrial

reptile

vibora/sumbadora

unidentified

unidentified

Tapachula

−17.8

9.3

modern

terrestrial

shellfish

concha

clam shell

unidentified

Aquiles Serdan, 1B/N8

−20.8

−1.8

shellfish

camarone

Shrimp

unidentified

Barra San Jose

−25.4

shellfish

camarone

shrimp

unidentified

Barra San Jose

shellfish

camarone

shrimp

unidentified

Barra San Jose

shellfish

cangrejo

crab

unidentified

shellfish

cangrejo

crab

unidentified

archaeological

estuary

6.3

modern

estuary

−20.3

5.9

modern

estuary

−25.9

4.8

modern

estuary

Barra San Jose

−22.1

5.6

modern

estuary

Barra San Jose

−23.9

6.0

modern

estuary

shellfish

camarone

shrimp

unidentified

Paredon

−11.7

2.2

modern

marine

shellfish

camarone

shrimp

unidentified

Tonala

−17.9

2.1

modern

marine

shellfish

camarone grande

giant shrimp

unidentified

Puerto Madero

−14.4

10.7

modern

marine

shellfish

camarone tigre

tiger shrimp

unidentified

Puerto Madero

−14.2

12.2

modern

marine

shellfish

mejillón

mussel

Mytelis sp.

Puerto Madero

−16.0

8.2

modern

marine

shellfish

camarone

shrimp

unidentified

Rio Coatan

−15.7

10.5

modern

river

shellfish

cangrejo

crab

unidentified

Rio Angostura

−17.2

3.3

modern

river

B. Chisholm and M. Blake

reptile reptile

C

H

A

P

T

E

R

13 Early to Terminal Classic Maya Diet in the Northern Lowlands of the Yucatán (Mexico) EUGENIA BROWN MANSELL*, ROBERT H. TYKOT†, DAVID A. FREIDEL‡, BRUCE H. DAHLIN§, AND TRACI ARDREN¶ *Department of Anthropology, University of South Florida, Tampa, Florida † Department of Anthropology, University of South Florida, Tampa, Florida ‡ Department of Anthropology, Southern Methodist University, Dallas, Texas § Department of Sociology and Anthropology, Howard University, Washington, D.C. ¶ Department of Anthropology, University of Miami, Coral Gables, Florida

Introduction 173 Methods 174 Isotopic Studies of the Maya 174 Discussion and Conclusion 180

lands and southern lowlands in Belize, Honduras, and Guatemala have been the subject of isotopic studies, recently the northern lowlands, in particular the Yucatán peninsula of Mexico, have been the subject of such research. Twentytwo individuals from Yaxuná, in the interior, and five from Chunchucmil, on the coastal plain, were specifically selected to provide some data for the Yucatán. Bone and tooth samples were prepared using well-established procedures to ensure integrity and reliability, especially considering the poor preservation of many skeletal remains from this region. Stable carbon and nitrogen isotope ratios were then measured for bone collagen, and carbon isotope ratios were measured for bone apatite and tooth enamel. The results suggest significant differences between the two Classic Maya sites, with the residents of Yaxuná consistently the most dependent on maize. There was also greater dietary variation among the individuals at Chunchucmil, probably because of the availability of diverse resources and differences related directly to social status.

Glossary Bone apatite The mineral component of bone that reflects the overall diet. Bone collagen The fibrous protein component of bone that reflects the protein in the diet. Chunchucmil Maya site located in the western part of the Yucatán peninsula. Classic Maya Cultural period ca. AD 250–900. Typically divided into Early Classic (ca. AD 250–550) and Late Classic (ca. AD 550–900). Stable carbon and nitrogen isotope analysis Used to divide consumed foods into discrete, isotopic groups (i.e., 13 C to 12C and 15N to 14N), leading to the understanding of the diet. Tooth enamel The outer surface of teeth, which reflects the diet at the time of tooth formation. Yucatán peninsula Peninsula in southeast Mexico that extends into the Gulf of Mexico. Yaxuná Maya site located in the north central part of the Yucatán peninsula.

INTRODUCTION In 1990, Vogt [20] wrote that maize composes up to 70% of the modern Maya diet, but ethnographic information does not necessarily translate into the diet of the ancient Maya. Although current research tells us that maize was a vital component of their diet, how vital was it? Were there differences in consumption among social groups, between geographic locales, or between genders? This stable isotope study has given us one of our first opportunities to evaluate the importance of maize in the Classic-Period Maya (AD

For more than a quarter century, stable isotope analysis of human skeletal remains has been used to determine the diet of ancient people. For the ancient Maya, the main questions have been focused on the reliance on maize and how it changed over time. Although many areas of the Maya high-

Histories of Maize

173

Copyright © 2006 by Academic Press. All rights of reproduction in any form reserved.

174

E. B. Mansell et al.

Chunchucmil Yaxuna

Santa Rita Cuello La Milpa Lamanai Mojo Cay Baking Pot Uaxactun Barton Ramie Holmul Pacbitun Cahal Pech Itzan Seibal Caracol Altar de Sacrificios Dos Pilas Aguateca

Iximche

Kaminaljuyu La Blanca

Copan

FIGURE 13-1 Map showing sites in the Yucatán and adjacent regions. (Courtesy of Eugenia Brown Mansell)

250 to AD 1050) of the northern Yucatán peninsula and to study differences among the diets of differing status groups at Yaxuná and Chunchucmil, including elites at Yaxuná and a possible middle class at Chunchucmil (Figure 13-1). The two assemblages also have given us an opportunity to further assess differences in diet among the different geographical areas of Yucatán. Thanks to the previous stable isotope studies by White and Schwarcz [22], Powis and colleagues [13], Gerry [7], Wright and Schwarz [25], Tykot and colleagues [19], and others we have an increasingly complete picture of the diet of the Southern Lowland Maya in ancient times [17]. However, our knowledge of the Northern Lowland Maya has been lacking. This chapter presents what we hope is the first of many other isotopic studies in the Northern Lowlands. Our study looks specifically at the diet of Early to Late–Terminal Classic people who lived at the sites of Yaxuná and Chunchucmil, both located in the state of Yucatán, Mexico. The purpose of this research is to assess dietary trends and how they reflect social and economic status, gender (at Yaxuná), and access to nourishment within the communities both chronologically and spatially.

METHODS Because of typical Maya Lowland environmental factors (i.e., humidity and limestone underlying thin soil), the

human skeletal material found at both sites was poorly preserved. Collagen was extracted following established procedures [18], including using a dilute hydrochloric acid solution to demineralize the bones, followed by sodium hydroxide to neutralize humic acids, and a defatting solution with methanol and chloroform to remove residual lipids. Powdered bone apatite and tooth enamel samples were treated in sodium hypochlorite to remove organics, and then in an acetic acetate buffer to remove nonbiogenic carbonates. Most samples yielded no collagen at all, with only three individuals each from Yaxuná and from Chunchucmil yielding 1% or more of sample. However, apatite was extracted from all bone samples and most of the teeth available. All samples were run on Finnigan MAT stable isotope ratio mass spectrometers at the University of South Florida, one using a CHN analyzer for collagen samples and the other using a Kiel III device for bone apatite and tooth enamel samples. Collagen yields and C : N ratios were used to confirm the integrity of the collagen isotope results, which are reported in Table 13-1. The analysis of the stable carbon and nitrogen isotopes for collagen yields the percentage of dietary protein in the individual tested, whereas the analysis of the stable carbon isotopes for apatite yields knowledge of the overall diet in the test subject. The analysis of tooth enamel provides information on diet at the age of tooth formation.

ISOTOPIC STUDIES OF THE MAYA The Maya adapted themselves to a range of ecological zones, including highlands, lowlands, and the coastal plains. In Belize most isotopic studies have been performed at sites on the wide, flat coastal plains, including Lamanai [22], Baking Pot and Barton Ramie [7], Pacbitun [21], Cuello [19], Cahal Pech [13], Colha [23], Altun Ha [23], and on the coast at Mojo Cay [12]. One study has been reported from the west central mountains at Caracol [4]. Elsewhere in Mesoamerica, isotope studies also have been published from the Peten [25]. Research has been done on the Peten area of Belize with a study at La Milpa [11]; this chapter presents a new study that adds the Northern Lowlands to the growing volume of knowledge.

Yaxuná The site of Yaxuná is located approximately 20 kilometers southwest of Chichén Itzá (Figure 13-1). Its placement in the central northern third of the peninsular has several advantages for subsistence. There is a greater rainfall than the coastal plain for agriculture, low scrub jungle rather than the high tropical rain forest of the Southern Lowlands for ease of seeing prey and clearing land for milpa (maize fields), and a good trade location at a crossroads linking the site

175

Early to Terminal Classic Maya Diet in the Northern Lowlands of the Yucatán (Mexico)

TABLE 13-1 Results of Stable Isotope Analysis at Yaxuná and Chunchucmil d13Cco

d15Nco

d13Cap

Sex/Age

Burial 6

F 25–35

−3.3

I

Burial 7

F 25–35

−3.6

I

−2.3

Burial 8

F 30–40

−4.1

I2

−0.1

M

−0.8

M1

−0.9

−4.2

M

−2.6

−1.2

M1

−1.0

M3

−3.7

−11.8

6.6

Tooth

d13Cen

Yaxuná

−6.2

Burial 9

F?

−2.9

Burial 11

FA

−3.3

Burial 13B

M YA

−4.1

Burial 13C

M 40+

−3.4

Burial 15A

M 40+

−2.9

Burial 16

M 30–35

Burial 17

M 25–40

Burial 23

M 40–50

−2.6

Burial 24-1

A 22–28

−1.4

M1

−2.8

Burial 24-2

J 12–15

−3.0

PM1

−2.8

Burial 24-3

J 7–9

−2.8

I

−3.4

Burial 24-4

J 10–12

−3.1

I

−3.4

Burial 24-5

F 34–45

−2.3

C

−2.1

Burial 24-6

F 20–25

−3.0

M2

−1.7

Burial 24-7

M 55+

−2.3

PM

−4.0

Burial 24-10

F 20–25

−2.5

PM

−2.4

Burial 24-11

M 50+

−2.5

PM

−2.4

Burial 24-12

J 0–0.5

Burial 24-13

F 40+

ave.

−12.9

7.3

−12.3

7.3

−8.1

−12.3

7.1

−3.2

−3.5

std. dev.

0.4 13

0.3 15

−2.5

1.4 13

1.5 13

Chunchucmil

Sex/Age

d Cco

d Nco

d Cap

Kaab’ 9D1.4 1999

? J/YA

−14.7

6.4

−8.2

’Aak 9C1.8 2000

? 12+

−13.4

7.6

−4.5

M2

−6.3

−5.2

M1

−7.7

−5.6

M1

−5.8

’Aak 9C1.9 1999 Kaab’ 9D1.2 2000

?A

Muuch 10A22.9.1 2001

? YA?

ave.

−16.0

Tooth

d Cen

7.0

−3.4

−14.7

7.0

−5.4

−6.6

1.1

0.5

1.6

0.8

std. dev.

with the east coast of the peninsular via a 100-kilometer sacbe (raised causeway) to Cobá. From 1986 to 1996, the Yaxuná Archaeological Project under the direction of David Freidel mapped 1.5 square kilometers of the site center and other portions of the site, and excavated and consolidated several large structures (Figure 13-2). We examined 22 individuals from the site, described in detail by S. Bennett [1–3]. We sampled the entire contents of two royal tombs, dating to the Early Classic (AD 250–550 or 600), and also 10 individuals (five females, five males) recovered from nonelite contexts around the site. These burials were found

primarily within crypts in modest house mounds that dated, based on ceramics, to the Late–Terminal Classic period (AD 550/600–1000), probably between AD 700 and 900 (Figure 13-3). The North Acropolis at Yaxuná is a large centrally located platform 11 meters high with an approximately 300-squaremeter plaza. On this plaza are three large buildings, two of which contained tombs. In 1993, excavations were begun on the 16.5-meter building on the north side of the plaza. It was during these excavations that the first undisturbed royal tomb in Yucatán was uncovered. The floor of the tomb was

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FIGURE 13-3 Map of Platform 6F, showing Structures 3 and 4. (Courtesy of Eugenia Brown Mansell)

FIGURE 13-2 Map of the central portion of Yaxuná. (Courtesy of Eugenia Brown Mansell)

The following year a tomb in an 8-meter structure on the eastern side of the plaza was discovered. It contained the remains of 11 individuals: one male, four females, one individual of undetermined sex, and four children placed around a decapitated adult male who had been centrally placed in the tomb. The excavators believe that the royal people had been terminated, ending their lineage. They were entombed in a terminated elite ceremonial building, which had another structure built over it. As in the previous tomb, there were elite grave goods: ceramics, carved shell, greenstone, and obsidian blades. A description of each individual follows.

fine, white marl, and the walls were covered in coarse stucco. There were multiple ceramic vessels placed in the tomb, such as four sealed miniature vessels, a polychrome shallow bowl, black bowl with a spout, two cups, and a jar. Also included in the grave goods were a turtle carapace, carved deer bones, three carved jade jewels, a shell pendant carved in the shape of a turtle or frog, and a death head carved from a spondylus shell. The body of one individual (Burial 23) was that of a 40–50-year-old male, who until death had apparently enjoyed good health, with no serious infections or trauma, although there was evidence of arthritis. It was determined by the Yaxuná-Project archaeologists that this individual had been a ruler at Yaxuná [16]. There was no collagen present for this individual; however the δ13C values obtained for apatite (−2.6‰) and for third molar tooth enamel (−3.7‰) suggest a high dependence on maize or maize-fed animals, both as a youngster and as an adult.

A. Burial 24-7 was a centrally placed, older male (55 years old or older), who had been decapitated, and his skull placed in another part of the tomb; all physical data from the Yaxuná burials were taken from the field reports of Sharon Bennett [1–3]. He had an apatite δ13C value of −2.3‰ and tooth-enamel value of −4.0‰ from a premolar, which were similar values to the older male in Burial 23. B. Burial 24-1 was an adult between the age of 22 and 28 years; a definite sex assignment was not possible. The apatite signature was −1.4‰, and the tooth-enamel value was −2.8‰ for a first molar. C. Burial 24-2 was at least 12 years old, but no more than 15 years old, based on dental evidence, and no sex was assigned. The skull had been crushed. The individual was interred with a necklace of jade and shell. The δ13C value for apatite was −3.0‰, and the value for tooth enamel from a first premolar was −2.8‰. D. Burial 24-3 was a small child, with the dental and epiphyseal evidence indicating that the child was between 7 and 9 years old. Apatite δ13C was −2.8‰ whereas the enamel from an incisor yielded −3.6‰.

Early to Terminal Classic Maya Diet in the Northern Lowlands of the Yucatán (Mexico)

E. Burial 24-4 was also a child between the age of 10 and 12 with an apatite signature of −3.1‰ and enamel value of −3.4‰, also from an incisor. Both burial 24-3 and 24-4, although they were children, contained a rich array of grave goods. F. Burial 24-5 was an older female who was between the age of 34 to 45 years, with an apatite δ13C reading of −2.3‰ and enamel from a bicuspid reading −2.1‰. G. Burial 24-6 was a female, 20 to 25 years old, with cut marks on the left tibia and the right femur. This woman was interred with many grave goods of jade, shell, and so on, and a unique polychrome ceramic figurine. The apatite δ13C value was −3.0‰, and the enamel value from a second molar was −1.7‰. H. Burial 24-10 was a female, 20 to 25 years old. The apatite value was −2.5‰, and tooth-enamel value from a premolar was −2.4‰. I. Burial 24-11 was a male more than 50 years old. The apatite δ13C value was −2.5‰, and the tooth-enamel value from a premolar was −2.4‰. J. Burial 24-12 was an infant, approximately newborn to 6 months. Despite the young age, this was the only individual in the tomb to produce collagen data (δ13C = −12.3‰; δ13C = 7.3) along with bone apatite results (δ13C = −8.1). K. Burial 24-13 was a decapitated female who was, in all probability, more than 40 years old. Her apatite signature was −3.5‰. There were no teeth associated with this individual. The centrally placed male and the young female with the figurine were carefully placed in the tomb. All of the other individuals were literally tossed into the crypt, but the richness of the grave goods indicates that they were interred with all of the trappings of royalty. The single collagen result for this tomb, from the infant, is in line with the two other collagen values produced for the Late Classic nonelite individuals. This value most likely represents less dependence on C4 resources; however, there is a trophic level effect in breastfeeding. The apatite δ13C value of −8.1‰ for this infant was more negative than any of the other individuals tested, suggesting far less direct dependence on maize and maize products for children of such a young age. The other 10 individuals tested, five females and five males, were recovered from nonelite contexts around the site. The burials were found primarily within crypts in modest house mounds that date, based on ceramics, to the Late–Terminal Classic Period (AD 550 or 600–1000), probably between AD 700–900. A. Burial 6 was a 25–35-year-old female recovered from a crypt. She had a Cehpech sphere (Late–Terminal Classic) vessel over her head and another below the femur. The apatite δ13C value was −3.3‰, and the tooth enamel δ13C value from an incisor was −6.2‰.

177

B. Burial 7 was a 25–35-year-old female with a Cehpech sphere vessel and probable deer bones. The apatite reading was −3.6‰, and the tooth enamel δ13C value from an incisor was −2.3‰. C. Burial 8 was a 30–40-year-old female with an apatite signature of −4.1‰ and tooth enamel value of −0.1‰ from an incisor. Burial 8 also had a collagen value of −11.8‰. She was interred with Cehpech sphere vessel over the skull. D. Burial 9 was a female of indeterminate adult age, interred with shell pendants and deer bones. The apatite δ13C value was −2.9‰, and the tooth-enamel value for a molar was −0.8‰. E. Burial 11 was an adult female with an apatite δ13C reading of −3.3‰. There were no teeth associated with this burial. She had three Cehpech sphere vessels interred with her. F. Burial 13C was a robust male older than 40 years, who was probably a warrior because the decapitated skull of a young adult male (Burial 13B) was interred with him, and he also had multiple grave goods. The ceramics are late Cehpech, suggesting Terminal Classic. The apatite δ13C for the young adult male (13B) was −4.1‰ and the tooth enamel value was −0.9‰ for a first molar. The warrior (13C) has an apatite signature of −3.4‰, and there were no teeth from this individual. G. Burial 15A was a male more than 40 years old with a Cehpech vessel over his head. The apatite δ13C value was −2.9‰. There were no teeth. H. Burial 16 was a 30–35-year-old male interred in a crypt. His apatite δ13C signature was −4.2‰, and his tooth-enamel value from a molar yielded a reading of −2.6‰. I. Burial 17 was a male who was 25–40 years old, and his crypt was disturbed by the construction of the crypt for Burial 16. He had a collagen signature of −12.9‰, an apatite value of −1.2‰, and the results for tooth enamel from a first molar was −1.0‰. Overall there is a high degree of consistency in stable isotope values for all of these individuals, indicating a great dependence—about 60–70% on average—on maize and maize products for the whole diet (as visible from the apatite). The collagen data, however, suggest that only 50% of dietary protein was represented by C4-based plants (e.g., maize), indicating that the diet was supplemented by C3 plants (e.g., beans that have a higher protein percentages than maize) and wild animals (e.g., deer).

Chunchucmil Chunchucmil is located 27 kilometers east of the Gulf of Mexico (Figure 13-4). It is an area of the Yucatán peninsula that has low rainfall and poor soil with little depth. Current

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Muuch

Kaab’

’Aak 250 meters

N

Map of Central Chunchucmil, with quadrangle groups and sacbes highlighted in gray and the ’Aak, Muuch, and Kaab’ groups highlighted in darker gray. FIGURE 13-4 Map of the site of Chunchucmil (Yucatán) showing residential groups with analyzed human skeletal materials. (Courtesy of Eugenia Brown Mansell)

estimates state that at its peak during the late Early Classic (ca. AD 400–550 or 600) the population of the site could have reached 29,680 to 46,648 [6]. The estimate is based on the unusually large number of house mounds found at the site. Chunchucmil, with its aridity and thin, impoverished soil, could not have grown enough maize to sustain a population of this size. Chunchucmil residents would have been importing foodstuffs: maize from areas to the east with

richer farm lands, marine resources from the nearby coast, and various floral and faunal foodstuffs available in the nearby savanna area. The five individuals included in this study were found in modest house mounds, in nonelite contexts. At least one individual (Burial 2), however, had grave goods generally associated with higher-status individuals [8]. All residential groups of this period at Chunchucmil are characterized

Early to Terminal Classic Maya Diet in the Northern Lowlands of the Yucatán (Mexico)

179

Kaab' Residential Group

M M M M M

Structure 23

10 meters

N

FIGURE 13-5 Map of Kaab’ residential group, Chunchucmil. (Courtesy of Eugenia Brown Mansell)

by structures arranged around a patio and enclosed by a stone wall [9]. Osteological analyses have been done by Stanley Serafin [14]. Burial 1 was recovered from the Kaab’ Group, a residential unit of three medium-sized mounds arranged on three sides of a common patio and several smaller structures arranged around a second southeastern patio (Figure 13-5). The group is located 300 meters from the site center. Burial 1 was a dedicatory burial at the base of the only vaulted structure at the group, Structure 23 (Figure 13-6). It was contained in a cist in the construction fill of the structure under a red painted plaster floor. The skeletal material was in a flexed position. A Teabo-Red vessel was placed over the skull, and a Dzibical vessel was to the east of the long bones

[10]. Both vessels date to the Late Classic (AD 550 or 600–800). A complete skeleton was not recovered, but the parts appear to be those of a juvenile or a small adult. The collagen δ13C value of this individual was −14.7‰, and the apatite value was −8.2‰. There were no teeth. Burial 5 also was recovered in Structure 32 of the Kaab’ Group. It was found on top of the floor in the southeast corner of Room 2. Again, only a partial skeleton was recovered, the skull and long bones of an adult [10]. There was no collagen preserved, although the carbon isotope reading was −5.6‰ for apatite and −5.8‰ for tooth enamel from a first molar. Burials 2 and 3 were recovered from the ’Aak Group, another residential group of six structures located 600

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FIGURE 13-6 Map of Structure 23 showing burials, ’Aak residential group, Chunchucmil. (Courtesy of Eugenia Brown Mansell)

meters from the site center (Figure 13-7). Structure 23, the tallest (2 m) structure at the group, yielded two burials under large stone slabs at a depth of 130 centimeters. Burial 2 consisted of disarticulated bones surrounded by three complete vessels: one was an elaborately carved Acu bowl. In addition, there were numerous jade and greenstone objects, a celt, pendant, and multiple round and tubular beads (Figure 13-8). The individual was at least 12 years of age based on teeth recovered but probably older. The collagen δ13C value was −13.4‰, the apatite value was −4.5‰, and the toothenamel value for a second molar was −6.3‰. Burial 3, on the northern edge of the unit, had fewer remains than Burial 2, only the long bones and a scapula, gathered and perhaps bundled, were recovered under a tripod shallow bowl [8]. There was no collagen recovered. The apatite δ13C value was −5.2‰ and the enamel value for a first molar was −7.7‰. The vessels in both burials date to the late Early Classic (AD 400–550 or 600). Burial 6, possibly a young adult, was recovered under construction fill while excavating a unit in Structure 16 of

the Muuch Group, a small residential albarrada group, just north of ’Aak (Figure 13-9). Burial 6 was a secondary burial; the remains, consisting of a portion of the zygomatic arch, several long bone fragments, and three premolars, had been placed in a large Maxcanu cazuela (basin) (Figure 13-10). Dental evidence indicates that the individual was a young adult. The collagen δ13C value was −16.0‰, and the apatite value was −3.4‰. There was no enamel reading recovered. There were two identical Kanachen dishes and two nearly identical Hunabchen vessels dating to the Early Classic in association with the burial; all were crushed under construction fill [15]. As with Burial 3, these vessels dated to the late Early Classic period; all physical data from the Chunchucmil burials were taken from the field report of Serafin [14]. The burials from Chunchucmil, although not elite, had a large quantity of grave goods. This could represent a “middle class” with a market economy based on trade and exchange, because Chunchucmil probably controlled the second largest salt flats in Mesoamerica and the first salt flats reached when traveling from central Mexico. Even though the sample size is small, it is clear from the stable isotope data that neither maize nor maize-fed animals were quite the critical contributors to the diet as at Yaxuná, and supports the hypothesis that low rainfall and poor soil limited maize production. At the same time, there is no isotopic indication that maize was substituted for by any marine resources, because they likely would have increased δ13C and δ15N values in collagen and δ13C values in bone apatite and tooth enamel. Instead, it appears that there was increased reliance on C3 plants (e.g., squash and beans), whether locally produced or imported, and their consumers.

DISCUSSION AND CONCLUSION Comparison of the data from Yaxuná and Chunchucmil with published results for Pre-Classic, Classic, and PostClassic sites across the Maya area indicates that the importance of maize to dietary protein of these two sites from the northern lowlands was similar to many sites in Belize (Figure 13-11) but clearly less important than for sites in the Peten and Guatemala (Figure 13-12). The collagen carbon isotope data for Chunchucmil clearly suggest that maize was far less important in the diet there, when compared with the Belize sites and Yaxuná. The bone apatite carbon isotope data, which measures the whole diet, illustrate the importance of doing isotope analysis on more than collagen samples. Apatite data are especially important when the research is meant to address the significance of plant foods such as maize, which have low protein content. The bone apatite and collagen data produced for Yaxuná strongly suggest that maize (and/or other C4/CAM plants that were directly consumed by humans) was of significance to the

Early to Terminal Classic Maya Diet in the Northern Lowlands of the Yucatán (Mexico)

181

Structure 14 M M

Structure 16

Structure 13

M

Structure 17 M Structure 15

20 meters

N

FIGURE 13-7 Map of ’Aak residential group, Chunchucmil. (Courtesy of Eugenia Brown Mansell)

overall Maya diet in the central portion of the Yucatán peninsula, similar to Belize or other adjacent regions (Figure 13-13). In contrast, in Chunchucmil, which was located in a poor agricultural region and close to a variety of ecological regions and trading routes, people relied less on maize. At the same time, a greater percentage of dietary protein at Yaxuná and Chunchucmil, compared to Belize and elsewhere, must have ultimately come from foods with C3-like carbon isotope values. Although the lower nitrogen isotope ratios for both Chunchucmil and Yaxuná most likely indicate that their more negative collagen carbon isotope values did not result from greater consumption of typical terrestrial or riverine fauna, which are mostly protein and thus have a much greater effect on human collagen values than do plants, fauna in this region need to be isotopically tested, because they could have lower average nitrogen isotope

values compared to those from Belize. Another interpretation would be that beans and other legumes were of greater importance in the Yucatán than in Belize. The isotope data clearly indicate that other sources of information, perhaps faunal isotopic studies, about diet in the Yucatán must be examined to test the hypotheses and potential interpretations presented here. When compared with Chunchucmil, it appears that more rain and deeper soil allowed the people of Yaxuná to grow maize according to their needs; indeed, the people of modern Yaxuná rely on their milpa more than the contemporary people of Chunchucmil (Mansell, personal observation). The skeletal remains of ancient Yaxuná do not evidence a lack of sustenance; the population appears to have been in good health. There appears to be no evidence of gender and status differences in diet or a temporal difference. Their relatively

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M = in situ metate –M = metate reused in wall = albarrada

Str. 32 M M M

M M M M M

M M M M M

–M –M

M –M

20 meters

FIGURE 13-8 Map of Structure 22 showing burials, ’Aak residential group, Chunchucmil. (Courtesy of Eugenia Brown Mansell)

FIGURE 13-9 Map of Muuch residential group, Chunchucmil. (Courtesy of Eugenia Brown Mansell)

FIGURE 13-10 Map of Structure 16 showing burial, Muuch residential group, Chunchucmil. (Courtesy of Eugenia Brown Mansell)

N

183

Early to Terminal Classic Maya Diet in the Northern Lowlands of the Yucatán (Mexico)

14

delta 15N (per mil)

12

Baking Pot (LC) Barton Ramie (EC) Barton Ramie (LC) Cahal Pech (Pre-C) Cahal Pech (LC) Cuello (Pre-C) Lamanai (Pre-C) Lamanai (EC) Lamanai (LC/TC) Lamanai (Post-C) Lamanai (H) Pacbitun (EC) Pacbitun (LC/TC) La Milpa (LC/TC) Yaxuna Chunchucmil

10

8

6

Yaxuná

Chunchucmil

4

2

0 –20

–18

–16

–14

–12

–10

–8

delta 13C (per mil)

–6

–4

Note: Mojo Cay (coastal) not shown

FIGURE 13-11 Collagen stable isotope data for Yucatán sites of Chunchucmil asnd Yaxuná compared with data for sites in Belize. (Courtesy of Eugenia Brown Mansell)

14

delta 15N (per mil)

12 Aguateca (LC) Altar (Pre-C) Altar (EC) Altar (LC) Altar (TC) Dos Pilas (LC) Dos Pilas (TC) Holmul (EC) Holmul (LC) Itzan (LC) Seibal (Pre-C) Seibal (EC) Seibal (LC) Seibal (TC) Uaxactun (LC) Iximche (Post-C) Yaxuna Chunchucmil

10

Chunchucmil 8

6

Yaxuná 4

2

0

–20

–18

–16

–14

–12

–10

–8

–6

–4

delta 13C (per mil) FIGURE 13-12 Collagen data for Yucatán sites of Chunchucmil and Yaxuná compared with data for sites in the Peten and Guatemala. (Courtesy of Eugenia Brown Mansell)

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Cuello (Pre-C) Programme for Belize La Milpa (LC/TC) Chunchucmil (EC/LC) Yaxuná (EC/LC)

–12

–10

–8

–6

–4

–2

0

2

d13C apatite (per mil)

FIGURE 13-13 Bone apatite data for Chunchucmil and Yaxuná compared with selected sites in Belize. (Courtesy of Eugenia Brown Mansell)

greater reliance on maize, however, may have been directly related to their environment and the lack of diversity in its resources. In contrast, the people of Chunchucmil, unable to grow enough maize to feed their large population on the regionally marginal agricultural resources that the area provided, were probably fortunate that the site occupied a strategic location along a well-established maritime trade route through its port, Punta Canbalam, enabling the site to receive a diversity of subsistence goods. Also, the fact that they abutted an environmentally rich savanna and wetlands greatly improved their ability to provide a variety of nutrients for their population. Dietary gender differences cannot be studied with the Chunchucmil sample because the poorly preserved skeletal material cannot be sexed in most cases. Moreover, because all the burials were from nonelite contexts, we cannot evaluate dietary differences based on social status. Future investigations may possibly reveal whether the Chunchucmil elite and nonelite populations had a similar diet as those from Yaxuná. From these two small studies, it appears likely that environmental factors are a great determinate to a population’s reliance on maize in Northern Yucatán. We await other studies to confirm this conclusion. We feel confident that in the Northern Lowlands, the location of a site and the availability of local and foreign resources was a determining factor in the overall diet of the resident population.

Acknowledgments We would like to thank Aline Magnoni, Scott Hutson, and Traci Ardren for their help with the illustrations, suggestions, and patience during the writing of the chapter.

References Cited 1. S. Bennett. (1991). Burials at Yaxuná, Yucatán. The Selz Foundation Yaxuná Project. In: D. Freidel, C. Suhler, R. Cobos, (Eds.), Final report of the 1991 field season. México: INAH, Mérida, Yucatán. 2. S. Bennett. (1992). Burials from Yaxuná, Yucatán. The Selz Foundation Yaxuná Project. In: C. Suhler, D. Freidel, (Eds.), Final report of the 1992 field season. México: INAH, Mérida, Yucatán.

3. S. Bennett. (1993). The burial excavations at Yaxuná in 1993. The Selz Foundation Yaxuná Project. Final Report of the 1993 Field Season. México: INAH, Mérida, Yucatán. 4. D. Z. Chase, A. F. Chase, C. D. White, W. Giddens. (1998). Human skeletal remains in archaeological context: Status, diet, and household at Caracol, Belize. Paper presented at the 14th International Congress of Anthropological and Ethnological Sciences, Williamsburg, Virginia, July 27, 1998. 5. B. H. Dahlin, T. Ardren. (2002). Modes of exchange and their effects on regional and urban patterns at Chunchucmil, Yucatán, México. In: M. A. Masson, D. Freidel, (Eds.), Ancient Maya political economies. Walnut Creek, CA: Altamira Press. pp. 249–284. 6. B. H. Dahlin, T. Beach, S. Lazzader-Beach, A. Magnoni, S. R. Hutson, E. B. Mansell, D. Mazeau. (In press). Reconstructing agricultural selfsufficiency at Chunchucmil, Yucatán, México. Ancient Mesoamerica. 7. J. P. Gerry. (1993). Diet and status among the Classic Maya: An isotopic perspective. Ph.D dissertation. Cambridge, MA: Harvard University. 8. S. Hutson. (2000). Excavations in the ’Aak Group. In: W. Stanton, (Ed.), Pakbeh regional economy program: Report of the 2000 field season. México: INAH, Mérida, Yucatán. 9. S. Hutson, A. Magnoni, T. Stanton. (2004). House Rules? The practice of social organization in Classic Period Chunchucmil, Yucatán, Mexico. Ancient Mesoamerica, 15, 73–90. 10. A. Magnoni. (2001). Excavations at the Kaab’ Group. In: B. H. Dahlin, D. Mazeau, (Eds.), Pakbeh regional economy program: Report of the 2001 field season. México: INAH, Mérida, Yucatán. 11. E. B. Mansell, R. H. Tykot, F. Valdes, N. Hammond. (2000). Stable isotope analysis of human remains at La Milpa, Belize. Paper presented at the 65th Annual Meeting of the Society for American Archaeology, Philadelphia, Pennsylvania, April 5–9, 2000. 12. L. C. Norr. (1991). Nutritional consequences of prehistoric subsistence strategies in lower central America. Ph.D. dissertation. Urbana, IL: University of Illinois. 13. T. G. Powis, N. Stanchly, C. D. White, P. F. Healy, J. J. Awe, F. Longstaffe. (1999). A reconstruction of Middle Preclassic Maya subsistence economy at Cahal Pech, Belize. Antiquity, 73, 364–376. 14. S. Serafin. (2004). Osteological analyses of the human skeletal remains. In: S. R. Hutson, (Ed.), Pakbeh regional economy program: Report of the 2004 field season. México: INAH, Mérida, Yucatán. 15. T. W. Stanton. (2001). Horizontal excavations at the Muuch Group. In: B. H. Dahlin, D. Mazeau, (Eds.), Pakbeh regional economy program: Report of the 2001 field season. México: INAH, Mérida, Yucatán. 16. C. K. Suhler. (1996). Excavations at the North Acropolis, Yaxuná, Yucatán, México. Ph.D. dissertation. Dallas, TX: Southern Methodist University. 17. R. H. Tykot. (2002). Contribution of stable isotope analysis to understanding dietary variation among the Maya. In: K. Jakes, (Ed.), Archaeological chemistry. Materials, methods, and meaning. ACS Symposium Series 831. Washington, D.C.: American Chemical Society. pp. 214–230. 18. R. H. Tykot. (2004). Stable isotopes and diet: You are what you eat. In: M. Martini, M. Milazzo, M. Piacentini, (Eds.), Physics methods in archaeometry. Bologna, Italy: Società Italiana di Fisica. pp. 433–444. 19. R. H. Tykot, N. J. van der Merwe, N. Hammond. (1996). Stable isotope analysis of bone collagen, bone apatite, and tooth enamel in the reconstruction of human diet: A case study from Cuello, Belize. In: M. V. Orna, (Ed.), Archaeological chemistry: Organic, inorganic, and biochemical analysis. ACS Symposium Series 625. Washington, D.C.: American Chemical Society. pp. 355–365. 20. E. Z. Vogt. (1990). The Zinacantecos of Mexico: A modern Maya way of life. New York: Harcourt Brace Jovanovich. 21. C. D. White, P. F. Healy, H. P. Schwarcz. (1993). Intensive agriculture, social status, and Maya diet at Pacbitun, Belize. Journal of Anthropological Research, 49, 347–375.

Early to Terminal Classic Maya Diet in the Northern Lowlands of the Yucatán (Mexico) 22. C. D. White, H. P. Schwarcz. (1989). Ancient Maya diet: As inferred from isotopic and elemental analysis of human bone. Journal of Archaeological Science, 16, 451–474. 23. C. D. White, D. M. Pendergast, F. J. Longstaffe, K. R. Law. (2001). Social complexity and food systems at Altun Ha, Belize: The isotopic evidence. Latin American Antiquity, 12, 371–393.

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24. C. D. White, M. E. D. Pohl, H. P. Schwarcz, F. J. Longstaffe. (2001). Isotopic evidence for Maya patterns of deer and dog use at Preclassic Colha. Journal of Archaeological Science, 28, 89–107. 25. L. E. Wright, H. P. Schwarcz. (1996). Infrared and isotopic evidence for diagenesis of bone apatite at Dos Pilas, Guatemala: Paleodietary implications. Journal of Archaeological Science, 23, 933–944.

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14 The Importance of Maize in Initial Period and Early Horizon Peru ROBERT H. TYKOT*, RICHARD L. BURGER†, AND NIKOLAAS J. VAN DER MERWE‡ *Department of Anthropology, University of South Florida, Tampa, Florida † Department of Anthropology, Yale University, New Haven, Connecticut ‡ Archaeology Department, University of Cape Town, Rondebosch, South Africa

Introduction 187 Archaeological Sites Tested 188 Stable Isotope Analysis 191 Results and Discussion 193 Conclusion 195

gen and apatite from Pacopampa in highland northern Peru, and Cardal and Tablada de Lurin in the Lurin Valley on the central coast. Measurement of δ13C in apatite, which reflects the whole diet, is now recognized as an essential complement to δ13C and δ15N determinations for collagen, which represent only dietary protein, especially when both maize and marine foods may have been consumed. Hair segments from Mina Perdida, near the coast, are being analyzed to assess short-term or seasonal variations in diet. The Pacopampa results are consistent with data from Chavín de Huantar and Huaricoto, indicating that maize was of secondary importance in highland subsistence systems during the Initial Period and Early Horizon Period. Near the coast in Lurin, marine foods were dietary staples, although maize consumption increased during the first millennium BC. These dietary reconstructions are important for understanding the development of intensive agricultural systems in coastal and highland Peru and the complex relationship between the subsistence economy and the emergence of early civilizations.

Glossary Cardal A late Initial Period complex site in the lower Lurin Valley with maize phytoliths recovered from a public center. Early Horizon First millennium BC period in Peru characterized by such complex sites as Chavin de Huantar. Mina Perdida The oldest of the Initial Period U-shaped centers in the lower Lurin Valley, with special packets of preserved hair found in a ritual context. Pacopampa A large late Initial Period–Early Horizon public center in the northern highlands with evidence for significant contact with Chavin de Huantar. Tablada de Lurin An extensive cemetery complex in the lower Lurin Valley dating to the final centuries of the early Horizon to the initial centuries of the Early Intermediate Period.

INTRODUCTION In Burger and van de Merwe’s 1990 article, it was concluded that maize was not the staple of highland Chavin civilization in the Mosna Valley or for the highland populations prior to this time in the neighboring Callejon de Huaylas [8]. However, it was recognized that this conclusion was not assumed to be valid for the other regions that played a role in stimulating Chavin civilization during the Initial Period or that interacted with it during Early Horizon. The different ecological conditions further to the north in the highlands of the Department of Cajamarca and in the arid coastal drainages of the Pacific created different challenges for

The relationship between food production and the development of complex societies has been an important focus of anthropological research in Peru, where maize traditionally was assumed to have been an important staple crop for Chavín civilization (ca. 850–200 BC) along the coast and in the highlands. Recent macrobotanical and chemical investigations have raised doubts about this hypothesis. In this study the relative contributions of maize and marine resources to pre-Hispanic Peruvian diet was determined through stable isotope analysis of human bone colla-

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farming from those at Chavin de Huantar and could have led to the incorporation of maize into the diet at different times and in different ways. In recognition of this, Burger and van der Merwe [8] wrote: Moreover, the far northern highlands are better suited for maize cultivation and less well suited for camelid herding because they are lower and moister. Until additional research is carried out, the role of maize in the development of the pre-Chavin and Chavinrelated cultures in these highland areas and on the coast remains very much an open question.

The analysis of the samples reported and discussed in this chapter are an attempt to use isotope analysis to address the question of maize consumption in some of the coastal and northern highland sites that played such an important role in the development of Chavin de Huantar. Although the number of samples is limited due to the scarcity of osteological and other human remains recovered from these archaeological centers, the findings shed light on dietary patterning and can serve as the basis for hypotheses that will be tested in the future as additional samples become available for study.

ARCHAEOLOGICAL SITES TESTED Pacopampa Pacopampa is a large public center established during the late Initial Period and occupied continuously through the

Early Horizon. Its most conspicuous remains consist of a series of terraced stone platforms with rectangular plazas, stone sculpture, masonry columns, and an elaborate stonelined drainage system. Pacopampa was considered to be a “colony” of Chavin de Huantar by Rebecca Carrion Cachot [10], but subsequent excavations at the site by Rosas and Shady [27, 28], Flores [16], Fung [17], and Morales [24, 25] have established the local character and development of this northern site, which is located only 150 kilometers south of the Ecuadorian border. Nevertheless, there seems to have been significant contact between Pacopampa and Chavin de Huantar throughout its occupation, and the ties between the sites were particularly close during Early Horizon. Today, Pacopampa is found within the District of Querocoto, Province of Chota, in the Department of Cajamarca at an elevation of 2140 meters above sea level (masl). The ceremonial core of Pacopampa covers approximately 10 hectares, an area comparable to the monumental core of Chavin de Huantar. As at Chavin de Huantar, some residential occupation exists at the site, although its full extent has yet to be determined. Morales [25, p. 117] estimates that if the residential areas are included, Pacopampa would cover an area 400 meters wide and 1000 meters long. Located roughly equidistant from the Pacific shores of northern Peru and the heavily forested tropical banks of the Marañon River, Pacopampa had strong exchange ties with coastal and eastern lowland peoples as well as the highland peoples further to the south, and these links have been confirmed by archaeological research [13, 31]. Unlike the formative center at Chavin de Huantar, which is located at the bottom of a deep valley at 3150 masl, Pacopampa is placed on the crest of a hill in the jalca zone (2000–2900 masl), about 1000 meters above the deeply entrenched Chotano River. As a consequence, most of the agricultural land within Pacopampa’s catchment area is in the surrounding quechua zone or the lower yunga-like temple zone (1200–2000 masl). These lands are suitable for

FIGURE 14-1 Map showing archaeological sites in Peru with stable

FIGURE 14-2 Panorama of the Pacopampa platforms and surrounding

isotope analyses.

environment. Photo: R. Burger.

The Importance of Maize in Initial Period and Early Horizon Peru

maize, manioc, sweet potato, fruit trees (such as chirimoya), and other crops that cannot thrive in the Chavin de Huantar area. Some native crops, such as arracacha, are popular in the Pacopampa area but are absent in the more southern highlands of Ancash. Because of this ecological setting, it is a distinct possibility that maize was a more important crop at Pacopampa than at Chavin de Huantar. Moreover, sites dating to the beginning of the Initial Period have only been found on steep slopes below the higher but more level lands surrounding Pacopampa [30]. Morales [25, p. 120] writes: Maize is a special case given that the geographic location of Pacopampa and the climate are the most apt for its cultivation. It is a seasonal cultivar using a dry farming technique, and each region produces two different varieties: a small hard one from the temple zone and a soft large one from the quechua zone. Maize never is grown alone since in the temple it is always grown with beans and in the quechua it is always together with squash.

German archaeologist Kaulicke [21, pp. 10–16] has suggested that the establishment of the large center at higher elevations in the quechua zone could have reflected a shift to an agricultural system emphasizing maize. It is also worth noting that the high altitude grasslands in far northern highlands around Pacopampa are moister than those around Chavin de Huantar and farther south, and the presence of camelids there appears to have first occurred as a result of the relatively late introduction of the domesticated llama (Llama glama) [23]. As a consequence of this ecological and historical pattern, the availability of large mammals in the Pacopampa area seems to have been somewhat restricted at least through the late Initial Period, and this may have had some effect on the introduction of maize into the diet. The samples analyzed were taken from an area known as El Mirador (the Lookout) located to the east of Pacopampa’s public architecture. Although some have treated El Mirador as a site separate from Pacopampa, its excavators have generally considered it to be one of the residential sectors surrounding the monumental core. El Mirador (PA–003) has been investigated by a series of archaeologists from the Universidad Nacional Mayor de San Marcos, first under the direction of Flores [16] and subsequently under the direction of Morales [24]. It has been described by Morales [25, p. 116] as containing the remains of worked stone, hearths, and kilns for making ceramics. Judging from their results, El Mirador was occupied from the late Initial Period until the Early Intermediate Period. The work has been limited in scope, but excavations of the lowest cultural level revealed a large ovoid structure that had been cut into bedrock. The edges of the floor were ringed with stones, which may have once supported a conical thatch roof covering the building. The structure was associated with abundant food refuse, broken pottery, and elaborate shattered figurines. Morales (personal communication) interpreted this building as the residence of religious specialists serving the temple area and

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given the presence of cut and burnt human bone amidst the faunal remains, hypothesized that ritual cannibalism took place. The pottery associated with the ovoid building and human remains falls within the Pacopampa Pacopampa Phase of Rosas and Shady or the Fase Apogeo of Morales, tentatively dated to the late Initial Period. He estimates the date of this phase to 1000–800 BC [25, p. 118]; judging from the style, it appears to be at least partially coeval with the Urabarriu Phase at Chavin de Huantar, dating to roughly between 900–600 BC. From the large sample of human remains recovered by Morales [25] at El Mirador, 11 rib samples were selected and exported with permission of the Instituto Nacional de Cultura for isotopic analysis. The samples came from units 4–6 in layer C and were associated with Fase Apogeo (or Pacopampa Pacopampa Phase) pottery. An effort was made to select ribs that, based on their size, color, and other features, represented different individuals. In addition, one large mammal rib, probably from a deer, was also analyzed for comparison with the human remains.

The Manchay Culture Sites of the Lurin Valley The Lurin Valley is a medium-sized valley on Peru’s central coast that is best known for the archaeological site of Pachacamac, one of the most important pilgrimage centers in late Pre-Hispanic times. At present, the valley is located immediately to the south of Lima, although it is quickly being incorporated in the capital’s sprawling suburbs. Long before Pachacamac was established, the Lurin Valley was characterized by the Manchay culture, a pre-Chavin cultural pattern that extended from Lurin through the Rimac Valley, the Chillon Valley, and the Chancay Valley. The most conspicuous expression of this culture was numerous public centers with monumental terraced platforms arranged in a U-shaped ground plan around a large rectangular plaza area. The Manchay flourished in the lower and middle valley areas of the central coast during the Initial Period (1800–800 BC, uncalibrated) and survived at some sites into the first centuries of the Early Horizon (800–650 BC, uncalibrated). In the Lurin Valley, seven civic–ceremonial centers have been identified in the lower valley and three in the middle valley. The centers of the Manchay culture seem to have been established at different points during the Initial Period, and this pattern has been interpreted as reflecting the gradual settlement of the valley by irrigation-based farmers as newly constructed gravity canals gradually brought the valley’s bottomland into cultivation, thus allowing the population to rise. The Manchay culture has been hypothesized to have been one of the principal sources of inspiration for highland Chavin culture, and contact existed between the central coast centers and Chavin de Huantar at the end of the Initial Period [2, 7].

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Since 1985, Burger and Salazar have been conducting research on the Manchay culture centers in the Lurin Valley, carrying out excavations at three of the civic– ceremonial centers. The arid climate of the central coast favors good preservation of the floral remains, but the intensive irrigation that has gone on in this area probably since late Pre-Ceramic times has offset these favorable environmental conditions. Macrobotanical studies of remains from the Manchay centers in the Lurin Valley by Umlauf [40] and Chevalier [11] have identified a wide range of cultivated and wild plants of economic value. Although these include macrobotanical maize remains, they are extremely rare and appear to be of secondary importance. However, in a phytolith study of one U-shaped center, Cardal, maize phytoliths proved to be abundant and widespread in all of the excavation units sampled. Given the preservation and sampling bias of the macrobotanic and phytolith studies, it would be premature to generalize about the importance of maize to Initial Period diet without additional kinds of analyses. Of the three centers investigated, Manchay Bajo has yet to yield human remains of any kind. Burials were found at Cardal on the summit of its central pyramid and in the residential area behind it, and 38 individuals were sampled for isotopic analysis.

Mina Perdida The site of Mina Perdida (PV48–117) is located 7.5 kilometers inland from the Pacific Ocean at 100 meters above sea level. Situated only 0.5 kilometer from the modern town of Pachacamac, which was established in colonial times following the destruction and abandonment of the Pre-Hispanic temple and settlement of the same name, Mina Perdida is the largest and oldest of the U-shaped centers in the Lurin Valley. The badly damaged site covers approximately 30 hectares, and its central terraced pyramid rises 22 meters above the valley floor. Judging from 18 C14 measurements, the site was established around 2000 BC and continued to thrive until 900 BC, in calibrated radiocarbon years. The site appears to have been abandoned before the emergence of Chavin civilization in the highlands. Excavations behind the central pyramid encountered evidence of temporary residential occupation during the late Initial Period, but there is little surviving evidence of a permanent population at the site. In the residential area, abundant shellfish and fish remains were recovered, but no fishing paraphernalia was recovered. This has led Burger [7] to suggest that the people associated with Mina Perdida, like those associated with Cardal, were probably farmers who obtained their marine foods by trading with fishermen and fisherwomen living along the shoreline at sites such as Curayacu or Chira-Villa. Abundant fish and shellfish remains have been encountered in all of the midden strata at Mina Perdida, Cardal, and Manchay Bajo, and it can be assumed that these marine

FIGURE 14-3 Central platform mound at Mina Perdida, Valley of Lurin. Photo: R. Burger.

animals were the principal sources of protein for the population [3, 18]. Occasional bones of ocean birds, inland birds, sea mammals, and wild large mammals (deer and wild camelid) were also encountered in small quantities. The hair samples analyzed for this study come from the 1991 excavations in the low stone-faced platform that constitute the left arm of the U-shaped complex. This area, known as sector IA, had been damaged by heavy machinery, but excavations revealed a complex series of small incremental additions that resulted in the growth of the platform both horizontally and vertically. Most of these additions consisted of the creation of stone retaining walls holding back stone, gravel, and/or earth. These artificial fills rarely contained cultural materials of any kind. During its final widening, coarse stone walls were built at short intervals perpendicular to the older platform wall; one of these small additions was unique because it included large quantities of cultural materials such as ceramics, textiles, fragments of native copper foil, and shell and plant remains [4, 6, 7]. Also in this fill were small packets of hair carefully secured by wrapping horizontal hairs around the packets. The reason for creating these packets of hair is unknown, but it is worth noting that hair has special symbolic power in the central Andes, and the first hair cutting ceremony remains an important rite of passage for children in traditional Quechua households. In contemporary Peru, hair is sometimes used in witchcraft and other rituals, so it retains some of its power even after it has been cut. All of the materials in the fill appear to be homogeneous and to date to the late Initial Period. A sample from a fiber bag that held the fill that included the hair samples produced a date of 2870 ± 90 BP (1210–920 CAL BC), and the hair should predate this time. Carbon sample taken from the fill in which the hair was found dated to 3050 ± 90 BP (1430–1160 CAL BC), and a sample taken from a wall built immediately before the deposition of the materials yielded

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under the direction of Makowski [22]. An attempt was made to select individuals whose sex and approximate age was known and to draw upon the full range of individuals along these two dimensions.

STABLE ISOTOPE ANALYSIS

FIGURE 14-4 Beginning of excavations in Sector IA, the damaged left arm of the U-shaped complex of Mina Perdida, where the hair samples analyzed were recovered. Photo: R. Burger.

a date of 2960 ± 90 BP (1320–1040 CAL BC). Although it is possible that the hair samples could have been taken from an older context and redeposited, it is likely that they date sometime between 1410–1090 CAL BC. In the selection of the nine samples, an effort was made to select hair samples with diverse visual characteristics from different contexts, and it is assumed that the nine samples represent nine separate individuals.

Tablada de Lurin In the lower Lurin Valley, extensive cemeteries exist on a sandy plateau at 100 meters above sea level above the north banks of the drainage. This area has been intensively studied by scholars from the Pontificia Universidad Catolica del Peru, Lima, beginning in 1958 and, thus far, half a hectare has been exposed revealing 437 burials [9]. The cultural affiliation of these burials pertains to the pre-Lima culture of the late Early Horizon–early Early Intermediate Period, and the date of the materials is estimated as falling between 200 BC–AD 200 [22, p. 92]. This culture followed the collapse both of the Manchay culture in the valley and of the Chavin culture whose influence is evident on those groups still living in the lower reaches of the valleys on the central coast. Although the Tablada de Lurin does not include residential or public architecture, relatively nearby sites with such remains have been documented for Lurin, most notably in the area of Villa Salvador [32, 33]. The cemetery is only 12 kilometers from the Pacific, and marine foods feature prominently in the burials and the midden of the coeval residential zone at Villa Salvador, so it can be assumed that marine foods remained an important part of diet. The sample of human bone analyzed from Tablada de Lurin came from burials excavated by the PUC project

The extraction and preparation of all 71 samples (69 human, 2 deer) was performed in the Archaeometry Laboratories, Harvard University, using well-established methods [35, 38]. The isotopic analysis was done on a VG Prism II stable isotope ratio mass spectrometer using an on-line Carlo Erba CHN analyzer for sample combustion. Carbon and nitrogen isotope data (Table 14-1) are reported relative to the PDB and AIR standards respectively using the delta (δ) notation with units in parts per mil (‰). Precision is ± 0.1 for δ13C and ± 0.2 for δ15N. The integrity of individual samples was assessed from their collagen yield (≥1%) and the ratio of elemental C : N produced by combustion (accepted if between 2.9 and 3.8). Although all 11 of the Pacopampa samples produced reliable isotope results, only 5 of the 12 Tablada de Lurin samples produced reliable collagen values, with three samples yielding no collagen at all, and 4 resulting in unacceptable C : N ratios when analyzed on the mass spectrometer. Data were also produced for the two deer samples from Pacopampa and Tablada de Lurin. Preservation was much worse for Cardal, with only 2 of the 38 individuals yielding any organic sample, and the isotopic results for both of those were rejected based on their unreliable C : N ratios. In contrast, reliable results were obtained, as expected, on the hair samples from Mina Perdida, which were carefully cleaned before isotopic analysis. In addition to carbon and nitrogen isotope results for homogenized samples from all nine individuals, reliable carbon isotope values were obtained for small, short-length increments for three individuals to investigate potential seasonal variation in diet. Because empirical evidence indicates that hair is about 1‰ lighter than bone collagen for δ13C, this difference has been taken into account in making comparisons with isotopic values of bone collagen in the discussion later. To also supplement the collagen data, which mainly reflects dietary protein, bone apatite samples were subsequently prepared in the Laboratory for Archaeological Science at the University of South Florida (USF) from all of the individuals from Pacopampa and Tablada de Lurin, and from a subset of 10 individuals from Cardal. These samples were analyzed at USF on a Finnigan MAT Delta Plus XL mass spectrometer equipped with a Kiel III individual acid bath system. Collagen carbon isotope values of about −20‰ are generally predicted for omnivorous human diets on the basis of direct or indirect consumption of C3 plants, whereas bone

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TABLE 14-1 Isotope Results for Peru Samples Tested in this Study Context/Sample No. El Miradaor, Pacopamapa Pp-c5 Pp-c5 Pp-c5 Pp-c6 Pp-c6 Pp-c6 Pp-c4 Pp-c4 Pp-c4 Pp-c4 average std. dev. Tablada de Lurin N169-173/E178-191, context 47 N595-100/E55-60, context 38 N171-174/E177-180, context EF#3 N125-135/E127-133, context 19 N590-95/E65-70, context 150EE S104-107/E6S-70, context 234 N171-174/E177-189, context GF31 N169-173/E178-181, context 47II Recinto 4, context 1 S104-107/E65-70, context 29III N125-135/E1227-133, context 17-I average std. dev. N123-126/E127-134, context 48-cc3 Cardal SM16 SM23 SM24 SM25 SM26 SM28 SM30 SM31 SM32 SM33 average std. dev. Mina Perdida Sector IA, unit 186, lens 6 Sector IA, unit 204, fill 10 Sector IA, units 167/188, lens 4 Sector IA, exc. 2, lens 8 Sector IA, unit 194/200, lens 11 Sector IA, unit 167, lens 4 Sector IA units 153/165, lens 3 Sector IA unit 167, lens 4 Sector IA units 194/206, lens 16 average std. dev. Sector IA, unit 204, fill 10 Sector IA, units 194/200, lens 11 Sector IA, unit 167, lens 4 Sector IA, unit 167, lens 4

Description

d13Cco

d15Nco

d13Cap

human rib human rib human rib human rib human rib human rib human rib human rib human rib human rib

−19.6 −19.6 −18.9 −18.4 −19.1 −19.4 −19.0 −19.1 −19.6 −19.6 −19.3 0.4

6.5 6.7 7.0 7.2 5.7 6.9 6.8 6.9 6.5 7.6 7.6 0.5

−10.8 −10.5 −11.4 −10.0 −10.1 −9.8 −9.6 −13.1

adult male adult male 21–23 adult female #4 adult female male, 17–20 adult female adult female adult male male 19–22 female > 30 adult female

−12.9

14.1 14.0

−9.1 −12.0

13.2 15.2

−8.4 −4.9 −7.8 −5.9 −4.8 −5.0 −4.3 −4.6

−11.5 −10.4 −11.2 1.3 −19.6

14.6 15.4 14.4 0.7 11.5

deer?

hair segments hair segments hair segments hair segments

−6.2 −4.9 −5.7 1.3 −11.5 −9.1 −12.0 −14.1 −12.0 −12.9 −13.3 −13.6 −13.1 −14.1 −13.6 −12.8 1.4

human bone human bone human bone human bone human bone human bone human bone human bone human bone human bone

human hair human hair human hair human hair human hair human hair human hair human hair human hair

−9.0 −9.0 1.2

−17.9 9.8 −21.0 12.7 −18.2 8.7 −17.7 9.3 −17.9 10.5 −17.9 11.0 −17.9 10.2 −17.4 11.2 −17.0 12.0 −18.1 10.6 1.1 1.2 −20.4/−20.5/−21.0/−20.7/ −20.1/−20.5 −17.7/−17.8/−17.9/−18.5 −16.7/−16.7/−16.1/−16.8 −16.9/−16.8/−16.6/−16.9

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apatite carbon isotope values for C3 consumers are thought to be in the range −16 to −14‰ on the basis of empirical data and on carbon isotope fractionation studies done on rats [1]. For inland sites where consumption of marine foods was unlikely, more positive values would strongly suggest the presence of maize in the Andean diet.

appear to have composed the bulk of their subsistence base. Our data (Table 14-1; Figure 14-5) further amplify the variability in Pre-Columbian Peruvian subsistence patterns and also illustrate the importance of isotopically analyzing both bone collagen and bone apatite when addressing the importance of plant foods in the diet.

Pacopampa

RESULTS AND DISCUSSION Although maize has been described as “the grain that civilized the New World,” [12, p. 1792] it is already clear that there was considerable variability in Pre-Columbian subsistence patterns, both in time and space. Coastal populations in Peru [14, 15, 34] and Ecuador [36, 41] relied extensively on marine foods and on maize in later periods. Similarly, although noticeable quantities of maize were consumed by highland populations in both the central [8] and northern Andes, its importance varied geographically and chronologically [37, 39]. Significant change over time in the importance of maize was in fact expected based on the ethnohistorical evidence [26, 29], which indicates that maize was the preeminent crop at the time of Spanish contact in the early sixteenth century AD. This has now been supported by stable isotope analyses of Inca period samples from Machu Picchu and Jauja [5, 19, 20], where maize does

The collagen carbon isotope results for Initial Period Pacopampa (δ13C = −19.3 ± 0.4‰, n = 11) at first suggest a pure C3 diet, with insignificant contributions from maize or marine foods. The bone apatite results (δ13C = −10.3 ± 1.2, n = 10), however, strongly support an estimate of maize and maize by-products representing at least 25% of the whole diet. Because maize is only about 10% protein, the negative carbon value for collagen can best be explained by the consumption of a significant amount of animal protein. Besides domesticated llama, wild deer, guinea pigs, and other animals may have been consumed regularly. There is little collagen carbon isotope difference between the Pacopampa individuals and the earlier study of four individuals from Chavin de Huantar (δ13C = −18.9 ± 0.1‰) [8], but without bone apatite analyses from the latter, it is not possible to state that maize was of similar importance at both sites. In comparison with data available for highland

18

delta 15N (per mil)

15

12 Pacopampa 9

Tablada de Lurin Mina Perdida

6

3

0 –24

–21

–18

–15

–12

–9

–6

delta 13C (per mil) FIGURE 14-5 Carbon versus nitrogen isotope values for bone collagen from sites in this study. Stable isotope ratios for hair corrected +1.0‰ to simulate collagen values.

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18

15 La Chimba Im-11

delta 15N (per mil)

12

Socapamba La Florida HS 9

La Florida LS Pacopampa

6

Chavin de Huantar Huaricoto

3

0 –24

–21

–18

–15

–12

–9

–6

delta 13C (per mil) FIGURE 14-6 Comparison of isotope data for sites in highland Peru and adjacent regions.

Ecuador (Figure 14-6), we see far less intrasite variability in the isotopic values for these two highland Peruvian sites. Individuals at the roughly contemporary site of La Chimba in northern highland Ecuador, at a considerably higher elevation (3200 masl), have not only noticeable quantities of maize in their protein diet but also considerable variation in its representation [37]. Later period sites in northern Ecuador exhibit even greater intrasite variability in maize consumption, in one case (La Florida) correlating to status differences [39].

Cardal Although it is unfortunate that no isotopic data for bone collagen from the Cardal samples were produced, the bone apatite results (δ13C = −12.8 ± 1.4‰, n = 10) are directly relevant to the whole diet and therefore the importance of maize and marine foods. Although one individual has a more positive carbon isotope value (−9.1‰), it is at first surprising that the bone apatite values are more negative than those obtained for the highland Pacopampa site, especially considering the abundance of maize phytoliths found and the proximity of the Pacific, not to mention the large amount of fish and shells recovered at Cardal. The limited isotope data for Cardal, therefore, strongly suggest less maize consumption than at Pacopampa and other sites, indicating that there

was significant variation in local agricultural and dietary practices. The significance of nonanimal dietary protein (e.g., from domesticated maize) is also expected to have been much greater in the highlands because wild mammals were scarce in most highland valleys.

Mina Perdida The isotopic values for the hair samples tested for nine individuals from contemporary Mina Perdida, close to Cardal and even closer to the Pacific coast, may be directly compared with the collagen results for the highland sites, again considering the impact of marine foods on isotope ratios. But first, an offset adjustment must be made because δ13C for hair is 1–2‰ more negative than collagen. The uncorrected values on the homogenized hair samples (δ13C = −18.1 ± 1.1‰, δ15N = 10.6 ± 1.2‰, n = 9) suggest fairly consistent dietary practices among the individuals represented. Whereas the noticeably enriched average carbon isotope ratio, compared with the highland sites, could be explained by greater significance of maize in the diet, the significantly enriched nitrogen isotope ratios strongly suggest that these values are due to marine foods contributing to the protein diet. This is supported by the finds at Mina Perdida, which, like Cardal, include refuse with huge amounts of shell, fish bone, and other marine products. With

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only hair samples for Mina Perdida, it is not possible to estimate the importance of low-protein maize in the diet. Somewhat surprisingly, there were negligible carbon isotopic differences for the sequential hair subsamples for the three individuals tested, suggesting little seasonal variation in the consumption of marine foods. The noticeable range in δ15N values for the nine individuals, however, does infer some variation in marine food consumption, perhaps in the particular kinds of fish and shellfish. Overall, because the Mina Perdida data are from hair samples, the heterogeneity observed may be a result of short-term dietary variability rather than different overall subsistence habits.

Tablada de Lurin The smaller sample of five individuals from the much later site of Tablada de Lurin is heavily enriched in both carbon and nitrogen isotopes for collagen and in carbon isotopes for bone apatite. Although the higher nitrogen values most likely reflect an even greater percentage of seafood (or at least of higher trophic-level fish and sea mammals), the even greater shift in collagen and apatite carbon isotope values strongly supports the idea that maize had become a significant dietary complement to marine foods by this time. This is not surprising considering that contemporary sites in coastal Ecuador [41] have much more enriched—and

variable—δ13C values, and at least in Ecuador have a history three millennia long of increasing maize reliance (Figure 14-7). The isotopic values of the Chorrera phase sites are instead similar to later Early Intermediate Period coastal sites in Peru, including Tablada de Lurin, Villa El Salvador [15], and Viru Valley sites 11 and 59 [14]. Significant dietary variation among sites is also not surprising, especially for Late Intermediate Period and Late Horizon societies where the local economy (and thus food availability) was politically controlled, as demonstrated by stable isotope studies at Pacatnamu [42] and several sites in the Osmore Valley [34]. Nevertheless, this considerable delay in the shift to intensive maize agriculture in Peru should be explored further.

CONCLUSION Other than stable isotope indications of maize consumption, the specific foods contributing to human diet can be positively identified mainly from faunal and archaeobotanical remains and ceramic residues found at archaeological sites. Along with ethnohistoric information, the entire process of food production, distribution, storage, ritual use, and so forth is best understood through the integration of such data. Stable isotope analyses provide significant, quantitative data,

18

Valdivia 1-3

15

Valdivia 4-7

delta 15N (per mil)

Machalilla Chorrera

12

Guangala Bahia/Manteno 9

Modern coastal Viru site 11 Viru site 59

6

Viru S100, 71 Viru 51, 217 Tablada de Lurin

3

Mina Perdida

0 –24

–21

–18

–15

–12

–9

–6

delta 13C (per mil) FIGURE 14-7 Comparison of isotope data for sites in coastal Peru and adjacent regions.

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especially about the importance of maize and its variation among sites and individuals. Further research on available domesticated plants, and on both wild and domesticated fauna, at the sites investigated in this study would add to the precision of our interpretations. Until then, we may tentatively conclude that domesticated maize was a significant and regular contributor to human diet by the late Initial Period, at least at some highland Peruvian sites when complex societies such as Chavin de Huantar developed; but it was not the dietary staple that it became in later prehistoric times. We can also observe that the stronger reliance on maize in the diet appears to have occurred in Ecuador centuries before it did in Peru, where it seems to have had a more important role in the highlands before it did along the coast.

References Cited 1. S. H. Ambrose, L. Norr. (1973). Experimental evidence for the relationship of the carbon isotope ratios of whole diet and dietary protein to those of bone collagen and carbonate. In: J. Lambert, G. Grupe, (Eds.), Prehistoric human bone: Archaeology at the molecular level. Berlin: Springer-Verlag. pp. 1–37. 2. R. L. Burger. (1992). Chavin and the origins of Andean civilization. London: Thames and Hudson. 3. R. L. Burger. (1997). The U-shaped pyramid complex, Cardal, Peru. National Geographic Research, 3, 363–375. 4. R. L. Burger, R. B. Gordon. (1998). Early Central Andean metalworking from Mina Perdida, Peru. Science, 281, 1108–1111. 5. R. Burger, J. A. Lee-Thorp, N. J. van der Merwe. (2003). Rite and crop in the Inca state revisited: An isotopic perspective from Machu Picchu and beyond. In: R. L. Burger, L. C. Salazar, (Eds.), The 1912 Yale Peruvian scientific expedition collections from Machu Picchu human and animal remains. New Haven, CT: Yale University Publications in Anthropology. pp. 119–137. 6. R. L. Burger, L. Salazar-Burger. (1998). A sacred effigy from Mina Perdida and the unseen ceremonies of the Peruvian Formative. RES, 33, 28–55. 7. R. L. Burger, L. Salazar-Burger. (2005). Investigaciones arqueológicas en Mina Perdida, Valle de Lurín, Perú. In: R. Burger, K. Makowski, (Eds.), Valle de Pachacamac I. Lima: Pontificia Universidad Catolica del Perú. 8. R. L. Burger, N. J. van der Merwe. (1990). Maize and the origin of highland Chavin Civilization: An isotopic perspective. American Anthropologist, 92, 85–95. 9. M. Cárdenas. (1990). Tablada de Lurín. Excavaciones 1958–1989. Patrones Fuerarios Tomo I. Instituto Rivera Aguero. Lima: Pontificia Universidad Catolica del Peru. 10. R. Carrión Cachot. (1948). La cultura Chavín: dos nuevas colonias Kuntur Wasi y Ancón. Revista del Museo Nacional de Antropología y Arqueología, 2, 99–172. 11. A. L. Chevalier. (2002). L’exploitation des plantes sur la cote peruvienne. Ph.D. dissertation. Universite de Geneve, Switzerland. 12. E. Culotta. (1991). How many genes had to change to produce corn? Science, 252, 1792–1793. 13. C. Elera. (1993). El complejo cultural Cupisniques: antecedentes y dessarrollo de su ideología religiosa. Senri Ethnological Studies, 37, 229–257. 14. J. E. Ericson, M. West, C. H. Sullivan, H. W. Krueger. (1989). The development of maize agriculture in the Viru valley, Peru. In: T. D. Price, (Ed.), The chemistry of prehistoric human bone. Cambridge, MA: Cambridge University Press. pp. 68–104.

15. N. Falk, R. H. Tykot, M. Delgado, E. A. Pechenkina, J. Vradenburg. (2004). Differential subsistence adaptations of agriculturalists and herders of the early intermediate period in the Lurin Valley, Peru: New data from stable isotope analysis. American Journal of Physical Anthropology, 123, 93. 16. I. Flores Espinoza. (1975). Excavaciones en el Mirador, Pacopampa. Seminario de Historia Rural Andino. Lima: Universidad Nacional Mayor de San Marcos. 17. R. Fung Pineda. (1975). Excavaciones en Pacopampa, Cajamarca. Revista del Museo Nacional, 41, 129–210. 18. M. Gorriti. (2005). El consumo de moluscos en el sito formativo de Mina Perdida. In: R. Burger, K. Makowski, (Eds.), Valle de Pachacamac I. Lima: Pontificia Universidad Católica del Perú. 19. C. Hastorf. (1990). The effect of the Inca State on Saysa agricultural production and crop consumption. American Antiquity, 50, 262–290. 20. C. Hastorf, S. Johannessen. (1993). Pre-Hispanic political change and the role of maize in the Central Andes of Peru. American Anthropologist, 95, 115–138. 21. P. Kaulicke. (1976). El Formativo de Pacopampa. Seminario de historia rural Andina. Lima: Universidad Nacional Mayor de San Marcos. 22. K. Makowski. (2002). Power and social ranking at the end of the Formative Period: The lower Lurín Valley cemeteries. In: W. H. Isbell, H. Silverman, (Eds.), Andean archaeology I. London: Blackwell. pp. 89–120. 23. G. R. Miller, R. L. Burger. (1995). Our father the cayman, our dinner the llama: Animal utilization at Chavin de Huantar. American Antiquity, 60, 421–458. 24. D. Morales Chocano. (1980). El dios felino en Pacopampa. Seminario de Historia Rural Andina. Lima: Universidad Nacional Mayor de San Marcos. 25. D. Morales Chocano. (1998). Investigaciones arqueológicas en Pacopampa, departamento de Cajamarca. Boletín de Arqueología PUCP 2, pp. 113–126. 26. G. Reichel-Dolmatoff. (1961). Agricultural basis of the sub-Andean chiefdoms of Colombia. In: J. Wilbert, (Ed.), The evolution of horticultural systems in native South America: Causes and consequences. Antropológica Supplemento no. 2. Caracas: Sociedad de Ciencias Naturales La Salle. pp. 83–100. 27. H. Rosas LaNoire, R. Shady Solis. (1970). Pacopampa, un centro formativo de la sierra norperuana. Seminario de Historia Rural Andina. Lima: Universidad Nacional Mayor de San Marcos. 28. H. Rosas LaNoire, R. Shady Solis. (1974). Sore el periodo formativo en la sierra del exremo norte del Perú. Arqueológicas, 15, 6–35. 29. F. Salomon. (1986). Native lords of Quito in the age of the Incas: The political economy of north Andean chiefdoms. Cambridge, MA: Cambridge University Press. 30. J. I. Santillana. (1975). Prospección arqueológica en Pacopampa. Seminario de historia rural Andino. Lima: Universidad Nacional Mayor de San Marcos. 31. R. Shady Solis, H. R. LaNoire. (1979). El complexjo Bagua y el estema de establecimiento durante el Formativo en la siera norte del Perú. Nawpa Pacha, 17, 109–142. 32. K. Stothert. (1980). The Villa el Salvador site and the beginning of the early intermediate period in the Lurin Valley, Peru. Journal of Field Archaeology, 7, 279–295. 33. K. Stothert, R. Ravines. (1977). Investigaciones arqueológicas en Villa el Salvador. Revista del Museo Nacional, 43, 157–226. 34. P. Tomczak. (2003). Prehistoric diet and socioeconomic relationships within the Osmore Valley of Southern Peru. Journal of Anthropological Archaeology, 22, 262–278. 35. R. H. Tykot. (2004). Stable isotopes and diet: You are what you eat. In: M. Martini, M. Milazzo, M. Piacentini, (Eds.), Physics methods in archaeometry. Bologna, Italy: Società Italiana di Fisica. pp. 433– 444.

The Importance of Maize in Initial Period and Early Horizon Peru 36. R. H. Tykot, J. E. Staller. (2002). The importance of early maize agriculture in coastal Ecuador: New data from la Emerenciana. Current Anthropology, 43, 666–677. 37. R. H. Tykot, N. J. van der Merwe, J. S. Athens. (1996). The dietary significance of prehistoric maize in the northern Andes: An isotopic perspective. Paper presented at the 61st Annual Meeting of the Society for American Archaeology, New Orleans Louisiana, April 11, 1996. 38. R. H. Tykot, N. J. van der Merwe, R. L. Burger. (1996). Isotopic investigations of dietary dichotomies: The importance of maize and marine foods to initial period/early horizon subsistence in highland and coastal Peru. Paper presented at the 30th International Symposium on Archaeometry, Urbana, Illinois, May 23–24, 1996. 39. D. H. Ubelaker, M. A. Katzenberg, L. G. Doyon. (1995). Status and diet in precontact highland Ecuador. American Journal of Physical Anthropology, 97, 403–411.

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40. M. Umlauf. (2005). Restos Botánicos de Cardal durante el Período Inicial, costa central del Perú. In: R. Burger, K. Makowski, (Eds.), Valle de Pachacamac I. Lima: Pontificia Universidad Catolica del Perú. 41. N. J. van der Merwe, J. A. Lee-Thorp, J. S. Raymond. (1993). Light, stable isotopes and the subsistence base of Formative cultures at Valdivia, Ecuador. In: J. B. Lambert, G. Grupe, (Eds.), Prehistoric human bone: Archaeology at the molecular level. Berlin: SpringerVerlag. pp. 63–97. 42. J. W. Verano, M. J. DeNiro. (1993). Locals or foreigners? Morphological, biometric, and isotopic approaches to the question of group affinity in human skeletal remains recovered from unusual archaeological contexts. In: M. K. Sandford, (Ed.), Investigations of ancient human tissue: Chemical analyses in anthropology. Langhorne, PA: Gordon and Breach Science Publishers. pp. 361–386.

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15 Maize on the Frontier Isotopic and Macrobotanical Data from Central–Western Argentina ADOLFO F. GIL*, ROBERT H. TYKOT†, GUSTAVO NEME‡, AND NICOLE R. SHELNUT§ *Departamento de Antropología, Museo de Historia Natural de San Rafael, San Rafael, Mendoza, Argentina † Department of Anthropology, University of South Florida, Tampa, Florida ‡ Departamento de Antropología, Museo de Historia Natural de San Rafael, San Rafael, Mendoza, Argentina § Department of Anthropology, University of South Florida, Tampa, Florida

Introduction 199 Zea mays on the Frontier: A South American Case 201 The Study Area 201 Domesticates: Maize and Other Resources in the Late Holocene 202 Isotopic Ecology and Human Diet: δ13C and δ15N Information 202 Late Holocene Human Diet and the Use of Maize 207 The Zea mays Frontier Adoption Model 211 Final Remarks 212

southern boundary of Pre-Hispanic maize agriculture and appeared to be an ideal location to explore the ways in which this cultigen was introduced. To understand this complex process, we introduce macrobotanical, archaeofaunal, and stable carbon and nitrogen isotope data from the southern region of province of Mendoza. We initially present the archaeobotanical and archaeofaunal record of late Holocene human occupation. The archaeological record for maize, its chronology and abundance is then presented and analyzed in comparison to other resources. The isotopic information includes late Holocene human bone collagen and apatite and tooth enamel samples, as well as animal and plant food resources from several environmental zones. We analyze these data and discuss the role of maize and temporal and spatial aspects of regional variability. Our results indicate that in general maize was never an economic staple and that there was an important variability in C4 resources use (possibly maize) in the past 4000 years. In contrast, the isotopic data and the kinds of resources exploited show a significant variability between lowland and highland piedmont. In light of these data, we discuss various models for the spread of maize in Argentina.

Glossary Guanaco Common name of Lama guanicoe. It is an important wild camelid of South America and is the biggest terrestrial game. It was an important subsistence resource to Pre-Hispanic hunter–gatherers. Intensification Process Greater foraging efficiency in response to resource scarcity. This implies bigger extraction cost of food and more productivity by area as a response to include in the human diet lower return rates resources. Piedmont The first elevation of the mountains in the transition between the lowland and the highland. In southern Mendoza the altitude is around 1300–1800 meters above sea level (masl). Puelches Historic hunter–gatherers who lived south of Mendoza during the Spanish contact.

INTRODUCTION In the past decades there has been an increase in efforts to understand not only the origins of plant domestication but also the incorporation of foreign domesticates imported from neighboring regions [61, 62]. Some research is focused on maize in North America [23, 25] and in South America [26, 59, 65]. In general, maize has been seen as central to

The introduction of maize is vital to understanding the dispersal of domesticates in Southern America. The Central–Western region of Argentina is thought to be the

Histories of Maize

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Copyright © 2006 by Academic Press. All rights of reproduction in any form reserved.

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domestication or assumed to be an important cause of cultural change where this resource appeared in the archaeological record. On the frontier, the region where the spread of this resource stopped, it is possible to expect some different regional histories and different consequences of the human strategies with respect to the places where the resources come, but there is little previous research on this topic [23, 25, 62]. This chapter focuses on the incorporation of maize in the southern Pre-Hispanic record, in the region located between northwest Argentina and north Patagonia (Figure 15-1). This region, central and southern Mendoza,

has been proposed as the South American farming frontier, and some hypotheses about the arrival of farming and its chronology have been published [32, 35, 52, 53]. In recent times, accelerator mass spectrometry (AMS) chronology was applied to maize, and stable isotope studies were used to discuss these hypotheses [20, 21, 46, 47]. In this study, the macrobotanical evidence, direct chronology, and stable carbon and nitrogen isotope data on resources and human archaeological samples are presented to understand the meaning of maize in its southern record. The isotopic information includes Holocene human bone collagen, bone

CORDILLERAN

R IV

ER

9

4

1 5 2

15 11

14 13 12

RIVER

16

R VE RI

3 6

PIEDMON T

AN D

ES

R RIVE

7 LA PAYUNIA

10 8

PATAGONIA

1. Cueva India embarazada; 2. Arroyo El Desecho; 3. Cerro Mesa; 4. Tierras blancas; 5. Ojo de agua; 6. El Chacay; 7. El Manzano; 8. Agua del Toro; 9. Capiz Alto; 10. La Matancilla; 11. Caæada Seca; 12. Jaime Prats; 13. Rincon del Atuel; 14. Gruta del Indio; 15. Medano Puesto Diaz; 16. RQ 1. FIGURE 15-1 The Pre-Hispanic archaeological sites considered in the chapter where domesticates were recorded.

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apatite, and tooth enamel samples, and animal and plant food resources from different environmental regions in central and southern Mendoza. With this information, the relevance of maize in the diet and its spatial and temporal variability is discussed.

ZEA MAYS ON THE FRONTIER: A SOUTH AMERICAN CASE The most important advance in the study of the incorporation of domesticates in Argentina was made in the 1970s. Little research has been developed regarding this topic [8], and few advances have been made in the past two decades [1, 39]. However, in worldwide research on plant domestication and its spread an important methodological, theoretical, and empirical advance has been realized in the past decade [61]. New standards about remains-recovery techniques, taxonomic identification, and chronology have been proposed, and they need to be incorporated firmly in the study of first farming populations in South America [48, 49, 60]. In South American research, it is suggested that domestication and spread was a slow process, which [1, 8] included different plants [48]. In the central–western part of Argentina, the present archaeological knowledge about the first farming and its role in Pre-Hispanic population has been developed in the same condition as in the rest of northwest Argentina. Until recently the flotation technique was not systematically used, and there are only a few domesticated samples directly dated [4, 21, 38, 39]. Almost all of the archaeological evidence of domesticates in this region come from dry caves. Research surrounding domesticates has generally focused on the chronology of the earliest domesticates, and this has usually been interpreted as evidence of an agricultural economy. The topic generally has been studied with cultural history reconstruction as a primary goal [18, 35, 38, 39]. Important points of debate have centered on whether the first domesticate was associated with ceramics, the chronological order of incorporation, and hypotheses about the origin of these “first farmers” [5, 18, 39, 54]. But little research had been done about the consequences of domesticate incorporation or the subsequent evolution of domesticates in the new human niche. In general terms, it has been assumed that the first record of domesticates has been a causal relationship with the transition to farming, the sedentary life, and the incorporation of ceramic technology [5]. The explanation for the arrival of domestication generally was from a move of human population or diffusions, but few studies have explored the endpoints of the spread and the subsequent history of domesticates after their incorporation. Some research hypothesizes ecological characteristics as significant factors in explaining this region as the last part where domesticates were used in Pre-Hispanic times [5, 33].

There is some regional variability in central–western Argentina in reference to the cultigens associated with the first records of domesticates. In San Juan there are PreHispanic records of Chenopodium quinoa, Cucurbita maxima, Cucurbita pepo, Lagenaria siceraria, Phaseolus vulgaris posteriorly Zea mays; and Arachis hypogaea has been recorded in the latest times [17, 51]. It was not a simultaneous incorporation process, and the first incorporation was quinoa and zapallo and later maize and bean [17]. North of Mendoza, Chenopodium quinoa, Lagenaria siceraria, and probably Zea mays are the oldest cultigens recorded [6, but see 18 for a discussion). In central southern Mendoza (see detail) Zea mays, Chenopodium quinoa, Cucurbita sp., and Phaseolus vulgaris are recorded contemporarily [38; but see 36, the Cucurbita sp.], and Lagenaria siceraria is chronologically recorded later [21]. The antiquity of maize in central–western Argentina has been a topic of acrimonious debate [5, 18, 39]. Some research has proposed an early entry of maize (ca. 4000 years BP) based basically on a kernel of maize [5, 6]. Other research accepts a later chronology to this domesticate (ca. 2000 years BP) [18, 35, 39]. The direct radiocarbon evidence on maize is in consort with the latter, but few directly dated Zea mays samples have been archaeologically recorded in the southern part of this region [21]. In general, the record of domesticates has been interpreted as the consequence of farming society settlement (see details in reference 19) and generally proposed in its first phase as “incipient farming” [17, 35]. If not in all cases, there are trends to assume the arrival of experimental farming families over a previous hunter–gatherer occupation [17, 39, 54, 63]. Recently alternative strategies to hunter–gatherer– farming dichotomy have been proposed and temporalspatial variability regarding the presence and use of maize is beginning to be considered [21, 47].

THE STUDY AREA The central and southern areas of Mendoza, located between 33–37° S and 70–67° W, is characterized by its environmental diversity, which includes the Andes Cordillera, a piedmont fringe extending along the mountain front, and a large plain (lowlands) (see Figure 15-1). Archaeologically this geographic portion is includes a mix of cultural areas or subareas: the southern part of central–western Argentina, a transition between central–western Argentina and Patagonia, and northern Patagonia. It is drained by several major streams: the Diamante, Atuel, and Grande rivers. The discharges of these streams are mainly controlled by snowfalls on their headwaters, which were repeatedly glaciated during the Pleistocene [66]. The Andes Cordillera consists of several North–South trending mountain ranges with mean elevations of

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5000–6000 masl and peaks up to 6500 masl, deeply eroded by both fluvial and glacial processes resulting in broad valleys. At ca. 35° S the mountain landscape is interrupted by the Huarpes depression, a structurally controlled depositional basin of relatively flat surface filled with PlioPleistocene deposits, placed between the High Andean ranges and the uplifted San Rafael Block (Figure 15-1). The piedmont fringe consists of several late Cenozoic alluvial fans and aggradations roughly situated between 1800 and 1000 masl, originating a series of gently sloping surfaces where the present fluvial system is degraded. The plain is an extensive landform descending from 400 to nearly 200 masl at the Desaguadero river. This plain is composed of alluvial sediments deposited by the Diamante and Atuel rivers and covered by a complex and extensive sand dune field. The southernmost part of this lowland comprises the La Payunia volcanic field, an area characterized by an irregular relief resulting from the occurrence of numerous volcanic cones, some reaching almost 3800 masl (Payún Liso volcano) with extensive basaltic plains [22]. The volcanic field has been eroded by local fluvial systems of ephemeral streams. Plant communities of several different phytogeographic provinces (i.e., Monte, Patagonia, High Andes, Subantarctic) are distributed following both altitudinal and latitudinal gradients [12].

DOMESTICATES: MAIZE AND OTHER RESOURCES IN THE LATE HOLOCENE Figure 15-1 shows the Pre-Hispanic archaeological sites where domesticates were recorded. Tables 15-1 and 15-2 list the plants and animals identified at archaeological sites (Figure 15-1). In Table 15-3 there is a list of domesticates recorded in the region with a detailed radiocarbon chronology. There are some observations to be made from the resource information. First, the cultigens recorded are Zea mays, Cucurbita sp., Chenopodium quinoa, Phaseolus vulgaris, and Lagenaria sp. Second, domesticates are less abundant than wild plants [28]. Third, Zea mays is the more ubiquitous domesticate: There are 17 sites with cultigens recorded and 16 have Zea mays; only one with Zea mays, Cucurbita sp., Chenopodium quinoa, Phaseolus vulgaris, and 12 with only Zea mays (Table 15-3). Fourth, it is clear that the domesticates, and particularly Zea mays, are more frequent in the middle Atuel Valley surrounding lowlands than in the rest of central–southern Mendoza (Figure 15-1; Table 15-3). The archaeological record of domesticates start ca. 2200 14C years BP, but only one site has domesticates directly dated in this early time (Gruta del Indio). Already by 1000 14C years BP there is wider distribution of domesticates, basically Zea mays, in central–southern Mendoza (Table 15-3). The wild plants

used are primarily algarrobo (Prosopis ssp.), Chenopodiaceae, Amaranthaceae, among others [27]. In general, they are C3 plants, but an exception can be Amaranthaceae [10]. Regional comparisons about the significance of different wild taxa in the human diet are complicated by the fact that there is only one archaeological site with quantitative archaeobotanical data available. There is no evidence of animal domestication or archaeofaunal reports of domestication in either central–southern Mendoza or in the rest of central–western Argentina [43]. Only in San Juan province there is archaeological evidence that could indicate the presence of domesticates in recent times [17]. In terms of caloric yield, guanaco (Lama guanicoe) have been the more important animal exploited, but the diversity of species exploited had a significant variability during the late Holocene and across the region [44]. Others species exploited were Rheidae, Dasypodidae, Testudinidae, and others [43, 44].

ISOTOPIC ECOLOGY AND HUMAN DIET: δ13C AND δ15N INFORMATION Well-established procedures for extracting bone collagen and bone and tooth enamel apatite were performed in the Laboratory for Archaeological Science at the University of South Florida [64]. Whole and fragmented bone (about 1 gram) and tooth samples were cleaned using ultrasonic vibration and distilled water. From the cleaned bone, 10 milligrams of bone powder were extracted for apatite analysis. Likewise, 10 milligrams of tooth enamel were extracted using a dental drill. Bone collagen was extracted using 2% HCl for 72 hours, dissolving base-soluble contaminants using 0.1 M NaOH (24 hours before and after demineralization), and separating residual lipids with a mixture of methanol, chloroform, and water for 24 hours. Collagen pseudomorphs were analyzed using a CHN-analyzed, coupled with a Finnigan MAT Delta Plus XL, stable isotope ratio mass spectrometer set up with a continuous flow. The reliability of collagen results were determined by percentage yield during processing, and validated by C : N ratios during analysis. Carbonate from apatite and enamel samples was also extracted using established techniques, specifically, the removal of organic components using bleach (24 hours for enamel, 72 hours for apatite), and of nonbiogenic carbonates using buffered 1 M acetic acid (24 hours). Carbonate samples were analyzed using a similar Finnegan MAT Delta Plus XL mass-spectrometer, coupled with a Kiel III device. The precision of the University of South Florida (USF) analyses is about ±0.1‰ for carbon and ±0.2‰ for nitrogen. Results are reported relative to the PDB and AIR standards. Isotopic information for local resources was obtained from 11 faunal samples (6 species) and 13 plant samples (11

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TABLE 15-1 A List of the Plants and Animals Identified at Archaeological Sites Shown in Figure 15-1 [27] Archaeological sites

Taxa Equisetum sp.

Gruta del Indio

Agua de los Caballos-1

Agua de la Mula-1

Ponontrehua

—

—

—

X X

Gramineae

X

X

X

Pappaphorum sp.

—

—

—

X

Phragmites comunis

X

—

—

—

Stipa sp.

X

—

—

—

Scirpus sp.

X

—

—

—

Stipa sp.

X

—

—

—

Sporobolus mendocinus

—

X

Cortaderia sp.

X

—

—

X

Tillandsia sp.

—

—

X

—

Ximenia americana

X

—

X

X

Chenopodiaceae

—

X

—

—

Chenopodium aff. hircinum

—

X

—

—

Chenopodium sp.

—

X

—

—

Amaranthaceae

X

X

—

—

Amaranthus caudatus

X

—

—

—

Bougainvillea spinosa

—

—

—

X

Atamisquea emarginata

—

—

X

—

Prosopis sp.

X

X

X

X

Caesalpinia gilliesii

—

—

X

—

Cassia aphylla

—

—

X

—

Geoffroea decorticans

X

X

X

X

Cercidiun australe

—

X

X

X

Larrea cuneifolia

X

X

—

X

Bulnesia retama

—

X

—

X

Schinus polygamus

—

X

X

—

Condalia microphylla

—

X

X

X

Sphaeralcea mendocina

—

X

—

—

Cactaceae

—

X

X

X

Cereus aethiops

—

X

—

—

Denmoza erythrocephala

—

X

Trichocereus candicans

—

X

X

X

Opuntia sulfurea

—

X

—

—

—

Verbenaceae

—

Cucurbitaceae

X

—

—

X

—

—

Proustia cuneifolia

—

—

X

X

Xanthium spinosum

—

X

—

—

Baccharis sp. ?

—

—

—

—

TABLE 15-2

A List of the Plants and Animals Identified at Archaeological Sites Shown in Figure 15-1 La Corredera

Los Leones-3

Los Leones-5

X

X

—

—

—

X

—

—

—

Cueva de

Alero Puesto

Cueva A°

Agua de Los

Puesto

Luna

Carrasco

Colorado

caballos-1

Ortubia-1

Ave indet.

X

X

X

X

—

Ave grde.

X

X

—

—

—

Ave chica

X

X

—

—

—

—

Taxa

Los peuquenes

Arroyo Malo-3

Arroyo Malo-1

Ojo de Agua

La Peligrosa-1 El Indígeno

X

X

—

X

—

X

—

—

—

X

—

—

X

—

—

—

—

Emberizidae

X

—

—

X

—

—

—

—

—

—

—

—

—

—

Zenadia auriculata

—

—

—

X

—

—

—

—

—

—

—

—

—

—

Eudromia elegans

—

—

—

X

—

—

—

—

—

—

—

—

—

—

Falconidae

X

—

—

—

—

—

—

—

—

—

—

—

—

—

Passeriiforme

X

—

—

X

—

—

—

—

—

—

—

—

—

—

Rheidae

X

X

—

—

—

X

—

—

—

—

—

X

X

—

Pterocnemia pennata

X

X

—

—

—

—

—

—

—

—

—

—

—

—

Rhea americana

—

X

—

—

X

—

—

—

—

—

—

X

—

—

Dasypodidae

X

X

X

X

X

X

X

X

—

X

—

X

X

—

Euphratyni

X

X

—

—

—

—

—

—

—

—

—

—

—

—

Chaetophractus sp.

X

X

—

—

—

—

—

—

—

—

—

—

—

—

Chaetophractus villosus

X

X

—

—

—

—

—

—

—

—

—

—

—

—

Zaedyus pichyi

X

X

—

X

—

—

X

X

—

—

—

—

—

—

Carnívoro

X

X

X

X

—

—

—

—

—

X

—

—

—

—

Conepatus sp.

X

X

—

—

—

—

—

—

—

—

—

—

—

—

Felis concolor

X

—

—

—

—

—

—

—

—

—

—

—

—

—

Artiodactyla

X

X

X

X

X

X

—

—

X

X

X

—

—

X

Camelidae

X

X

—

X

X

X

X

—

X

X

X

X

X

X

Lama Guanicoe

X

X

X

X

—

—

—

—

X

X

X

X

—

X

Ozotocerus bezoarticus

—

X

—

—

—

—

—

—

—

—

—

—

—

—

Lagidium viscacia

—

—

X

—

—

—

—

—

—

—

—

—

—

—

Mammalia indet

X

X

X

X

X

X

—

X

X

X

X

X

X

X

Mammalia (big size)

X

X

X

X

X

X

X

—

X

X

X

X

X

X

Mammalia (médium size)

X

—

—

X

—

—

—

—

—

—

—

—

—

—

Mammalia (small size)

—

X

—

X

X

X

X

—

—

—

—

—

—

—

Herviboro

—

—

—

X

X

—

—

—

X

—

—

—

—

—

Chiroptera

—

—

—

—

—

—

—

—

—

X

—

—

—

—

Reptilia

—

—

—

—

—

X

—

—

—

—

—

—

—

—

Iguánide

—

—

—

—

X

X

—

—

—

—

—

—

—

—

Testudinidae

—

—

—

X

X

X

—

—

—

—

—

—

—

—

Mollusca

—

—

—

—

—

—

—

—

X

—

—

—

—

—

Microvertebrados

X

X

X

X

X

X

X

—

X

X

—

—

X

—

205

Maize on the Frontier

TABLE 15-3 Southern Mendoza Domesticated. It is included the direct radiocarbon chronology or samples with direct primary contextual association. Archaeological site

Radiocarbon date

Taxa

References

2210 ± 90 (GrN-5493) 2095 ± 95 (GrN-5398) 2200 ± 70 (LP-823) 2065 ± 40 (GrN-5396)

Phaseolus vulgaris Phaseolus vulgaris Chenopodiun quinoa Zea mays Cucurbita sp.

[29, 30, 31, 38, 53, 55]

Reparo de las Pinturas Rojas

Zea mays

[34]

Zanjón del Morado

Zea mays

[34]

Cueva del Cerro Negro

Zea mays

[34]

Reparos del Rincón

Zea mays

[34]

Zea mays

[21, 31, 53]

Cueva Patas de Puma

Zea mays

[53]

Cueva Kilómetro 15

Zea mays

[53]

Cueva de la Bruja

Zea mays

[53]

Cueva Ponontrehue

Zea mays Cucurbita sp.

[34, 38]

Cueva Agua de la Mula

Zea mays Cucurbita sp.

[38]

Gruta del Indio

Zanjón del Buitre

605 ± 40 (AA-26195)

Gruta de Las Tinajas

modern (LP-1137)

Zea mays Cucurbita moschata

[40]

El Indígeno

1045 ± 45 (AA-26192)

Zea mays Lagenaria sp.

[37, 41, 42] [37, 41, 42]

Agua de los Caballos

365 ± 40 (AA-26196) 740 ± 40 (AA-26194)

Zea mays Zea mays

[20]

Puesto Ortubia-1

910 ± 40 (AA-26197)

Zea mays

[20]

Los Leones-5

Cucurbita sp. (?)

[20]

Puesto Carrasco

Lagenaria sp.

[14]

taxa) from this region (Table 15-4). The isotopic analyses indicate that, in general, the animals have a low value in δ13C (−19.2‰) and average δ15N value (4.6‰). In contrast, plants have a low δ13C value (−21.8‰) with average δ15N (7.2‰). The Zea mays δ13C values (avg. = −9.6‰) have no significant difference from corn samples from other regions, and they are enriched in carbon isotopic value in contrast to all noncorn plants tested. The δ15N value on domestic plants is highly variable with Cucurbita maxima and Lagenaria sp. having the highest values and Chenopodium quinoa, Phaseolus vulgaris, and Zea mays having the lowest values. The δ15N value on wild plants is higher in lowland than in highland areas with significant differences between the samples tested so far. This may be caused by differential responses to arid conditions and is the subject of further testing. The range of carbon isotope values in guanaco collagen sample is unexpectedly large (−19.1 to −14.2‰). A similar situation has been observed in North America with Bison bison [63]. The guanaco samples from lowlands have more

enriched δ13C. The other guanaco isotopic information comes from the piedmont and highland areas and is similar to guanaco isotopic values from other parts of Patagonia, around −19‰ [3, 15]. Camelid collagen samples recorded in the Puna, Fernández, and Panarello show a correlation between altitude and isotopic values, with the guanaco from low altitudinal levels having carbon isotopic values that are higher in respect to high altitudinal guanaco [15]. Cavagnaro [9] shows a clear pattern of grass distribution as a function of altitude where C4 is dominant at lower elevations and C3 is dominant in higher elevations. This grass distributional pattern parallels isotopic information from L. guanicoe in these regions. But there is only one sample of guanaco from each region and more information about the carbon isotopic value from this species will be obtained to check this trend. Another aspect to consider about the isotopic value of resources is that the δ15N value for highland resources is lower than in the rest of central–southern Mendoza. Unfortunately, there is not at present δ15N for fauna from lowland

206

TABLE 15-4 Taxa

Environment

Southern Mendoza Resources Isotopic Information (δ13C and δ15N) Location

Sample code

C:N

d15N ‰

d13Cco ‰

Code

d13Cca ‰

Code

d13Cen ‰

Lama guanicoe

Highland

Arroyo El Desecho-10 (A1-3-3-311)

USF-6170

3.3

—

−19.1

USF-5905

−10.7

—

—

Lama guanicoe

Lowlands

Agua de Los Caballos-1 (A1-11-414)

USF-6171

3.3

—

−14.2

USF-5906

—

—

—

Lama guanicoe

Footplain

Cueva de Luna (D4-6-67)

USF-6172

3.3

4.0

—

USF-5907

−11.1

—

—

Lama guanicoe

Highland

El Indígeno (H21-2)

—

—

—

—

—

—

USF-6173

−9.1

Lama guanicoe

Highland

El Indígeno (H21-3-18580)

USF-6179

3.4

4.3

−18.8

USF-5913

−8.9

—

—

Cholephaga melanoptera

Footplain

Actual (Malargue)

USF-6174

3.3

4.1

−22.0

USF-5908

−11.5

—

— —

Footplain

Alero Pto. Carrasco (S87-5-2)

USF-6175

3.4

5.7

−20.0

USF-5909

−11.8

—

Footplain

Alero Pto. Carrasco (S91-3B-36)

USF-6176

3.4

4.6

−20.6

USF-5910

−12.1

—

—

Pterocnemia pennata

Footplain

Alero Pto. Carrasco (S91-4-1553)

USF-6180

3.4

4.9

−21.0

USF-5914

−11.5

—

—

Lagidium viscacia

Highland

Arroyo El Desecho-10 (A1-6-2-402)

USF-6177

3.4

3.7

−19.3

USF-5911

−9.1

—

—

Chaetophractus villosus

Footplain

Alero Pto. Carrasco (S87-4-71)

USF-6178

3.3

5.6

−17.7

USF-5912

−11.1

—

—

Zea mays

Lowland

Cueva Zanjón del Buitre (seed)

USF-6181

—

3.4

−9.7

—

—

—

—

Zea mays

Lowland

Gruta del Indio (N°3500, seed)

USF-6182

—

3.9

−9.6

—

—

—

—

Cucurbita maxima

Lowland

Gruta del Indio (level 4; cáscara)

USF-6183

—

13.1

−23.2

—

—

—

—

Lagenaria sp.

USF-6184

—

10.4

−25.4

—

—

—

—

Chenopodium sp.

USF-6185

—

6.9

−27.6

—

—

—

—

−23.9

—

—

—

—

−24.9

—

—

—

—

Prosopis sp.

Lowland

Rincón del Atuel (fruit, actual)

USF-6186

—

Prosopis sp.

Lowland

Agua de Los Caballos-1 (level 6, endoca)

USF-6191

—

11.6

Cassia arnotiana

Highland

Arroyo Malo, actual (fruit)

USF-6187

—

1.6

−25.4

—

—

—

—

Phaseolus vulgaris var. oblongus

Lowland

Gruta del Indio (atuel II, seed)

USF-6188

—

5.5

−24.0

—

—

—

—

Geoffroea decorticans

Lowland

Agua de los Caballos (level 6, endocarpo)

USF-6189

—

14.0

−20.2

—

—

—

—

Geoffroea decorticans

Lowland

Rincón del Atuel (fruit, actual)

USF-6190

—

—

−20.8

—

—

—

—

Condalia microphylla

Lowland

Cuadro Benegas (actual, fruit)

USF-6192

—

—

−25.3

—

—

—

—

Schinus polygamus

Highland

Arroyo Malo, actual (fruit)

USF-6193

—

1.6

−24.4

—

—

—

—

A. F. Gil et al.

Rhea americana Pterocnemia pennata

207

Maize on the Frontier

areas, where a large number of the human samples come from. In this study, we processed 29 human samples, obtaining 25 δ15N and δ13C values for collagen (δ13Cco), 26 δ13C for carbonate (δ13Cca), and 16 δ13C for enamel (δ13Cen) (Table 15-5). These samples range chronologically over the past 5500 years, but primarily date to the past 2000 years (Table 15-5). They came from lowland (21 human samples from 9 archaeological sites), piedmont (6 human samples from 6 archaeological sites), and highland (2 human samples from 2 archaeological sites) regions. These samples have a δ15N average of 10.3‰ (SD: 1.4; range 6.4 to 12.9‰) and a δ13Cco average of −16.0‰ (SD: 1.5; range −18.8 to −13.9‰). In bone apatite, the δ13C average is −10.3‰ (SD: 1.5; range −13.0 to −7.9‰) and in the enamel the δ13C average is −10.5‰ (SD: 1.6; range −12.7 to −8.6‰). The δ13Cen average has little difference with δ13Cca. These results can be interpreted in terms of the C3/C4 ratio for the diet as showing a significant variability. In other regions, such as the Great Basin and the American Southwest, the carbon isotopic collagen value for great maize consumers range between −9.5 and −7.0‰ [10]. These authors propose three categories that represent real but not strictly categorical differences in diets: a) those who subsisted on diets high in C3 foods ( −14‰); and c) those subsisting on mixed diets (−17 to −14‰). The central–southern Mendoza isotopic values are significantly different from each other, but the average δ13Cco values (−16‰) show a mixed diet with medium to low or indirect consumption of C4. In our study, most individuals are in the third category, the first group is the second most abundant, and only one individual shows a high C4 foods diet. There are some differences in the isotopic values between lowland and highland piedmont regions. The δ13Cco values are more enriched in lowland samples (avg. = −15.3‰) than in highland piedmont samples (avg. = −17.4‰), but there is no significant variation in δ13Cca. The diet in highland piedmont areas was basically composed of more C3 resources in the protein fraction than in the lowland region, whereas the whole diet values are similar. This can be the result of more C4 protein in the diet, perhaps from more enriched guanaco in the lowlands than in the highlands, and/or by some C4 plant in diets poor in protein (the C4 plant probably more consumed is Zea mays). The lack of correlation between δ13Cco and δ15N suggest that the δ13Cco variation is due to direct or indirect C4 consumption (Figure 15-2). The human δ15N values are higher than the fauna tested and can indicate both arid–semiarid stress and the importance of meat consumption. There is no significant difference in δ15N values between lowland and highland piedmont samples, but there is an unexpectedly low highland outlier (sample AF-2038) that is difficult to explain.

There is a modest correlation (r2 = 0.42) between δ13Cco and δ13Cca, but there must have been some variation in the protein portion of the diet (Figure 15-3). It could be the result of diets with low animal consumption or the consumption of animals with enriched δ13C, such as the lowland guanacos [15]. It is significant to explore the difference between δ13Cco and δ13Cca (δ13Cca-co) as shown in Table 15-5, where an important range is observed in human samples with values between 3.9 and 7.6. Controlled feeding experiments demonstrated some meaning to these differences [2]. When δ13Cca-co is greater than 4.4, a diet of C4 carbohydrates and C3 protein is suggested. In contrast, if δ13Cca-co is less than 4.4, dietary protein is more enriched than that of whole diet. In general, the southern Mendoza human samples have δ13Cca-co greater than 4.4. This trend in δ13Cca-co is accepted as a pattern consistent with a situation where C4 plants (e.g., maize) are introduced into a C3 diet [24]. Only some lowland samples have δ13Cca-co less than 4.4, but they are near 4.4. In Figure 15-4 the relationship between δ13Cco and chronology is shown. The samples have been grouped each 1000 years and differentiation between highland piedmont and lowland regions is indicated. For the chronological definition, direct radiocarbon data, associated dated samples, and relative chronology have been used. There does not appear to be continuous enrichment in δ13Cco through time as would be expected from continuous incorporation of corn in the diet, as in other regions of the Americas (e.g., [10]). The highest average δ13Cco values are recorded between 3000 and 1000 BP (−14‰) basically centered in human samples from lowland sites dated 2800–1800 BP. For post1000 BP, there is a slight average decline to more negative δ13Cco (Figure 15-4), but there is greater variability within each temporal unit. Similar trends can be observed in the carbonate fraction of δ13C. It appears that consumption of the C4 resources starts around third millennium BP (sample GIRA70) at Gruta del Indio and that more enrichment of δ13Cco values come from lowland sites. In Figures 15-5 and 15-6 any chronological trends are analyzed only with human samples with direct radiometric data (i.e., those with direct chronology plus directly associated samples from the same archaeological site). In general these figures show no consistent trend to increase the isotopic value through time, with significant variability within each period. The specific locality from which samples were obtained, and the need for more samples from certain periods, may be limiting our interpretation.

LATE HOLOCENE HUMAN DIET AND THE USE OF MAIZE Recently the role of maize in diets of this region has been analyzed from different archaeological indicators [21, 46, 47]. The oldest macrobotanical remains of Zea mays in

208

TABLE 15-5

Human Samples with Isotopic Information (δ13C and δ15N)

Sample

Site

Area

Age and sex

USF

C:N

d15N

d13Cco

USF

d13Cca

USF

d13Cen

d13Cca-co

Lab code

AF-2036

India embarzada

highland

Female 16–20

6206

3.3

9.7

−17.5

6207

−10.1

6208

−10.8

7.4

AF-2038

El Desecho

highland

Female 39–49

6217

3.4

6.4

−18.8

6218

−11.2

—

—

AF-508

Cerro Mesa

piedmont

Male 38–49

6209

3.3

10.8

−17.9

6210

−12.2

6211

—

14

C

±

Temporal

AA-54672

2576

61

3

7.6

AA-54671

5502

60

6

5.7

—

—

—

1

piedmont

Female +50

7329

—

10.9

−17.9

7330

−13.0

7331

−12.7

4.9

—

—

—

1

Tierras Blancas

piedmont

Male 30–48

7332

—

9.5

−15.5

7333

−8.2

7334

−10.8

7.3

LP-890

200

—

1

AF-2022

Ojo de Agua

piedmont

Male 15–18

6194

3.3

10.5

−18.5

6195

—

6196

−11.9

—

LP-921

1280

50

2

Ent 3

El Chacay

piedmont

Male 25–30

7341

—

7.9

−16.2

7342

−9.2

7343

−10.2

7.0

AA-59591

2321

66

3

AF-510 AF-2025

El Manzano

piedmont

Male 35–43

7335

—

10.2

−17.2

7336

−12.5

7337

−12.8

4.7

—

—

—

—

Agua del Toro

lowland

Female 35–49

6212

3.3

12.9

−16.5

6213

−11.3

—

—

5.2

LP-1368

210

60

1

ENT-2

Capiz Alto

lowland

Female

6226

3.4

11.7

−14.9

6227

−10.6

6228

−9.6

4.3

LP-1381

1120

60

1

AF-505

La Matancilla

lowland

Male 45–50

6197

3.3

11.9

−16.0

6198

−10.1

—

—

5.9

LP-1379

470

50

1

CS-10001

Cañada Seca

lowland

Male 30–45

6199

3.3

11.6

−15.7

6200

−9.0

—

—

6.7

LP-1374

1420

60

2

lowland

Male +50

7349

—

10.4

−14.5

7350

−10.1

7351

−8.8

4.4

—

—

—

2 2

AF-2019 AF-2018

lowland

Male 30–40

7354

—

11.5

−14.3

7355

−9.8

7356

−9.0

4.5

—

—

—

AF-2020

lowland

Male 35–49

7357

—

11.3

−14.3

7358

−9.5

7359

−8.7

4.8

LP-1184

1790

50

2

lowland

Male (?) 35–49

7346

—

9.8

−17.4

7347

−13.5

7348

−13.5

3.9

AA-59590

1887

42

2

JP-1155

lowland

Female 20–24

6219

3.4

10.6

−16.8

6220

−10.2

6221

−8.6

6.6

—

—

2

JP-1352

lowland

34–49

7338

—

9.9

−16.3

7339

−10.6

7340

−11.2

5.7

AA-59589

1880

49

2

JP1155

lowland

7344

—

10.9

−16.0

7345

−9.3

—

—

6.7

—

—

—

2

JP/J4

AF-503

Jaime Prats

Rncon del Atuel

AF-500

—

lowland

Male 34–45

6203

—

—

—

6204

−7.9

6205

−9.9

—

—

—

—

2

lowland

Male >50

6222

—

—

—

6223

−8.1

—

—

—

LP-1370

1760

70

2

AF-500

lowland

Male +50

7365

—

9.5

−15.2

—

—

—

—

—

—

—

—

2

AF-503

lowland

Female 35–45

7366

—

9.2

−13.9

—

—

—

—

—

—

—

—

2

Gira-70

Gruta del Indio

GIRA-831

lowland

Adult

6201

3.3

10.8

−14.0

6202

−9.8

—

—

4.2

AA-54670

2879

37

3

lowland

25–49

7363

—

—

—

7364

−10.5

—

—

—

AA-59588

3944

46

4

GIRA-27

lowland

Adult

6224

—

—

—

6225

−11.9

—

—

—

—

—

—

—

AF-13894

lowland

perinatal

7352

—

9.8

−15.0

7353

−10.1

—

—

4.9

—

—

—

—

AF-681

Medano Puesto Diaz

lowland

Female 40–45

7360

—

8.7

−15.6

7361

−10.2

7362

−10.7

5.4

AA-59587

2865

52

3

MGA-1

RQ-1

lowland

—

6214

3.3

10.9

−14.2

6215

−8.9

6216

−8.7

5.3

—

—

—

—

A. F. Gil et al.

AF-673 AF-1082

209

Maize on the Frontier

14 13

15

N

12 11

lowland

10

highland & piedmont

9

highland-piedmont

8 lowland 7 6 5 4 –20

–18

–16 13

–14

–12

Cco

FIGURE 15-2 Correlation 15N/13Cco.

–6 –7 –8 2

R = 0.4238

13

Cca

–9 –10 –11 –12 –13 –14 –20

–19

–18

–17

–16

–15

13

Cco

FIGURE 15-3 Correlation 13Cco/13Cca.

–14

–13

–12

210

A. F. Gil et al.

–12 –13 –14 2

R = 0,0159 highland & piedmont lowland lowland highland

–16

13

Coc

–15

–17 –18

2

R = 0,2326

0-1000

1000-2000

2000-3000

3000-4000

4000-5000

–20

5000-6000

–19

0

FIGURE 15-4 Temporal trends 13Cco.

–12

–13

–14

13

Cco

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central–southern Mendoza are recorded ca. 2000 BP in the Atuel Valley, but are more ubiquitous after 1000 years BP [21]. Novellino and colleagues [47] analyzed the latitudinal variation in dental caries in central–western Argentina. They observed no correlation between δ13Cco value and caries frequency but a light latitudinal decrease in caries frequency that could indicate a relationship with the use of maize and other cariogenic resources (Prosopis ssp.?). In a recent paper it was proposed that δ13Cco of human samples from central–southern Mendoza have significant variation, from −20.2 to −14.1‰ [21]. No chronological change was observed in values of that paper’s collagen samples, which dated between ca. 2200 and 200 BP, a period in which there is a record of corn in the region. In this research there is now isotopic information on resources and δ13Cco, δ13Cca, δ13Cen, and δ15N information from human remains recorded in the past ca. 5500 years BP, that were not previously available. These isotopic values confirm the significant range of variation of the diet and add some significant knowledge. First, in the highland and piedmont regions the C4 resources were not generally significant in human diets. Second, in the lowland the human diet was highly variable between individuals with little C4 diet and others with moderate C4 diet. The more positive carbon isotopes values are grouped in the mid Atuel Valley, basically in Rincón del Atuel, Gruta del Indio, and Cañada Seca, but at the same time other close archaeological sites (e.g., Jaime Prats), have more negative isotopic values. In Jaime Prats, and between contemporary human samples, there is a wide range of variation in the δ13C values (Table 15-5). It exemplifies the high variability that characterizes the ratio of C3/C4 resources on the diet. Third, in reference to the temporal trends, these values show some individuals where the carbon isotope ratios are higher before 1000 years BP. It contrasts with the macrobotanical evidence for Zea mays, which shows a more ubiquitous record after 1000 years BP. The first record of Zea mays is later than the enriched δ13C samples from Gruta del Indio (Gira-70). Fourth, if the incorporation of Zea mays were an adaptive change, it would be expected to result in a continuous enrichment of δ13C, but that is not observed. Fifth, another important aspect to mention is that C4 resources never were uniformly used by the late Holocene human population in southern Mendoza. Instead, a high variability is observed for all times but especially in the lowlands. For north Mendoza there are few isotopic values available [16, 47]. The three samples come from the western mountain region and range over the past 2000 years. The δ13C data show an enrichment trend from −14 to −12‰; these values are higher than central–southern Mendoza but more isotopic values are requested to study the temporal variability in this part. For San Juan the first isotopic results are emerging and may show more temporal enrichment and spatial variability [56]. Preliminarily the general enrichment observed for San Juan and north Mendoza human samples

is not visible in central and southern Mendoza human samples.

THE ZEA MAYS FRONTIER ADOPTION MODEL Central–southern Mendoza is the South American frontier of Pre-Hispanic maize expansion [19, 21, 39]. The ethnographic descriptions present hunter–gatherers living with neighbors farming to the north and probably to the west in modern Chile [11, 50]. The chronicles describe an exchange pattern between the hunter–gatherers, called Puelches, and their transcordillerean farming neighbors. Maize was one of the products obtained by these hunter–gatherers [7, 45]. In historic times, maize was obtained in this form, but it needs to be explored if it happened before. If so, the meaning of social life and subsistence need to be analyzed in greater depth. In contrast, the significance of maize in the diet and its role in these groups needs to be studied. It is difficult to evaluate the significance of maize as a dietary staple if it were obtained by exchange [20, 21], in concordance with δ13C values for human samples recorded in the past 1000 years. In general, C4 resources were more important in the lowlands than in the highland piedmont areas, and in general less important than in north Mendoza and San Juan [47, 56]. The temporal trends of C4 plant consumption was as important—and variable—between 2800 and 1800 years BP as it was later. This point is interesting because maize was recorded archaeologically more abundant and regionally spread in the past 1000 years than before. This can be interpreted as a variation in the significance of C4 (maize?) in the diet. This high variability shows an economic or “adaptive” diversity, as also proposed for the Great Basin Freemont by Simms [57, 58]. This human strategy can be expected as a response to harsh environments where the cost of cultivating maize, and the adaptive risk and uncertainty, makes it highly unreliable within both a social and natural context. The data from the southern periphery show at least three periods of corn use. In the first period, when maize was incorporated in the lowlands, it was a medium to low component of diet. This occurred some time between 3000 and 2000 years BP if we consider the human samples chronology and their associated isotopic values. In central–southern Mendoza there is only one site with corn from this time, Gruta del Indio. Probably this strategy is what Lagiglia [39] calls “incipient farming exploration and colonization.” In later times, δ13Cca is higher (Figure 15-6) and shows a bigger difference than δ13Cco (Figure 15-5). Low-protein plant foods (e.g., maize) are reflected in carbonate when consumed in small quantities and are reflected in collagen only when consumed in sizeable proportions [24]. Some individ-

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FIGURE 15-6 Temporal 13Cca radiocarbon.

uals consumed medium amounts of C4 in their diets whereas others did not significantly consume these resources. At present, there are no maize samples attributed to the earlier dates, although around 2000 BP an intensification process appears to have started as a response to resource–human demography unbalance that could have affected the rest of central–southern Mendoza [41, 42]. Other authors, in relationship to this intensification process, propose farming pressure as a demographic growth from the north [13], but the relationship between intensification and farming expansion remains to be studied. Finally, the group of samples from the past 1000 years shows a lesser dependence on maize. There are maize samples to the south of Gruta del Indio, and they are more ubiquitous, with a wide geographic distribution. The oldest corn is recorded at the highland site of El Indígeno. The explanation for the decrease in isotopic δ13C value, or its lack of increase through time, is a point that needs to be considered but is consistent with historic information that does not describe maize use in this region by local societies.

FINAL REMARKS In the past decades, there has been an increased effort on the part of archaeologists to explain the adoption of new crops by populations or in the spread of domesticates [23].

It is difficult at this time to support the dualistic perspective where many scholars see the boundary between hunter–gatherers and agriculturalists as a continuum [62]. Maize was not used in the same way in all places and in all periods in South America [49]. The frontier of corn in the Pre-Hispanic record is a good region to evaluate the precondition, cause, and consequences of maize incorporation into the subsistence diet. Now the isotopic information shows a significant variation in C4 resources, both spatial and temporal, and it demonstrates that C4 resources were never a quantitatively significant part of human diets. But it is also necessary to understand isotopic variation compared with bioanthropological information about affiliation, mobility, and other indigenous resources. Some points are emerging and some problems as well. The information on resources shows that human samples from the highland piedmont regions are more likely to have δ13C values that directly reflect maize consumption, whereas the values obtained for guanaco in the lowlands make it difficult to measure direct maize consumption. Other aspects to consider include the potential of δ13C and δ15N values to reflect territoriality or mobility, or both, as an implication of significant variations in the isotopic structure of resources between lowland and highland piedmont regions. Another point that emerges is the relationship between the intensification process proposed to Atuel high valley, the chronology of the first corn, and the high variation on diet recorded in

Maize on the Frontier

the lowlands. The relationship among subsistence, technology, and land use, which could be recorded around 2000 years BP as a consequence of this process, needs to be analyzed with the domestication record and maize use. If this process is a response to macroregional change (i.e., farming expansion), it needs to be evaluated [13]. The lack of correlation between the archaeological abundance of maize and its consumption (as isotopically inferred) is a point that also needs to be explored. Variables including the role of maize in the diet, modes of obtaining it, and connections between different human populations (e.g., production vs. exchange; human migration vs. local incorporation) must be analyzed and discussed further. It is important not to confuse diet, strategies, subsistence, and technology in the discussion [62]. In the methodological aspect, the application of flotation, detailed archaeobotanical studies, and the increase of directly dated maize can confirm or deny the trends suggested here. Our data suggest that there is clear evidence of use of other C4 resources (i.e., Amaranthaceas), but no detailed archaeobotancal studies are available that discuss its significance in human diet, and it could be underrepresented in the interpretation of δ13C values. Finally, the ethnographic pattern of hunter–gatherers who obtained maize through exchange needs to be analyzed from a diachronic perspective to differentiate its dietary importance from those regions where it was locally cultivated and to more clearly understand its incorporation into various regional subsistence diets and its possible significance to demography, sedentism, and to complexity.

Acknowledgments Research was funded by Agencia Nacional de Investigación Científica y Técnica and Fundación Antorchas. We thank Paula Novellino and Humberto Lagiglia for providing some human samples and their valuable help in different stages of this research. All mistakes and omissions remain our own.

References Cited 1. M. Albeck. (2000). La vida agraria en los andes del sur. In: M. Tarragó, (Ed.), Los Pueblos originarios y la conquista. Buenos Aires, Argentina: Nueva Historia Argentina 1. pp. 187–228. 2. S. Ambrose, L. Norr. (1993). Experimental evidence for the relationship of the carbon isotope ratios of whole diet and dietary protein to those of bone collagen and carbonate. In: J. Lambert, G. Grupe, (Eds.), Prehistoric human bone: Archaeology at the molecular level. Berlin: Springer-Verlag. pp. 1–37. 3. R. Barbarena. (2003). Los límites del mar. Isótopos estables en Patagonia Meridional. Buenos Aires, Argentina: Sociedad Argentina de Antropología. 4. R. Bárcena. (1998). Arqueología de Mendoza. Las Dataciones Absolutas y sus Alcances. Mendoza, Argentina: EDIUNC, Universidad Nacional de Cuyo. 5. R. Bárcena. (2001). Prehistoria del Centro Oeste Argentino. In: E. Berberian, A. Nielsen, (Eds.), Historia Argentina Prehispánica. Córdoba; Argentina. pp. 561–634.

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45. G. Neme, A. Gil. (2004). Aportes para la Discusión del Intercambio en el sur de Mendoza. Report Manuscript. Departamento de Antropología. Mendoza, Argentina: Museo de Historia Natural de San Rafael. 46. P. Novellino, R. Guichón. (1999). Formas de subsistencias e isótopos estables en el sur de Mendoza. Revista de la Asociación Argentina de Antropología Biológica, 2, 323–334. 47. P. Novellino, A. Gil, G. Neme, V. Durán. (2004). El Consumo de maíz en el holoceno tardío del oeste argentino: Isótopos Estables y caries. Revista Española de Antropología Americana, 34, 85–110. 48. D. Pearsall. (1992). The origin of plant cultivation in South America. In: C. W. Cowan, P. J. Watson, (Eds.), The origins of agriculture. Washington, D.C.: Smithsonian Institution Press. pp. 173–205. 49. D. Pearsall. (1994). Issues in the analysis and interpretation of archaeological maize in South America. In: S. Johannessen, C. Hastorf, (Eds.), Corn and culture in the prehistoric New World. pp. 245–272. 50. M. Planella, B. Tagle. (2004). Inicios de presencia de cultígenos en la zona central de Chile, Períodos Arcaico y Agroalfarero Temprano. Chungara, 1 volumen especial, 387–399. 51. F. Roig. (1977). Frutos y Semillas Arqueológicos de Calingasta, San Juan. In: M. Gambier, (Ed.), La Cultura de Ansilta. San Juan: Instituto de Investigaciones Arqueológicas y Museo. pp. 216–250. 52. C. Rusconi. (1945). El maíz en las tumbas indígenas de Mendoza. Darwiniana, 7, 117–119. 53. C. Rusconi. (1962). Poblaciones pre y posthispánicas de Mendoza. 4 volúmenes. Mendoza, Argentina: Gobierno de Mendoza. 54. J. Schobinger. (1999). Las tierras Cuyanas. Nueva Historia de la Nación Argentina, 1, 159–180. 55. J. Semper. (1962–1968). H. Lagiglia, Excavaciones Arqueológicas en el Rincón del Atuel (Gruta del Indio). Revista Científica de Investigación, 1, 89–158. 56. N. Shelnut, A. Gil, R. Tykot, G. Neme, T. Michielli. (2004). Isótopos Estables y Dieta en el Centro Oeste Argentino: Recientes Datos Obtenidos Sobre Muestras Humanas de San Juan. Paper presented on the 14° Congreso Nacional de Arqueología Argentina, Río Cuarto, Córdoba. 57. S. Simms. (1986). New evidence for Fremont adaptive diversity. Journal of California and Great Basin Anthropology, 8, 204–216. 58. S. Simms. (1990). Fremont transition. Utah Archaeology, 6, 1–6. 59. J. Smalley, M. Blake. (2003). Sweet beginnings. Stalk sugar and the domestication of maize. Current Anthropology, 44, 675–703. 60. B. Smith. (1994/1995). The origins of agriculture in the Americas. Evolutionary Anthropology, 3, 174–184. 61. B. Smith. (2001). The transition to food production. In: G. Feinman, D. Price, (Eds.), Archaeology at the millennium: A sourcebook. New York: Kluwer Academic/Plenum Publisher. pp. 199–229. 62. B. Smith. (2001). Low–level food production. Journal of Archaeological Research, 9, 1–43. 63. K. Spielmann, M. Schoeninger, K. Moore. (1990). Plains–Pueblo interdependence and human diet at Pecos Pueblo, New Mexico. American Antiquity, 55, 745–765. 64. R. H. Tykot. (2004). Stable isotopes and diet: You are what you eat. In: M. Martini, M. Milazzo, M. Piacentini, (Eds.), Physics methods in archaeometry. Proceedings of the International School of Physics “Enrico Fermi” Course 154. Bologna, Italy: Società Italiana di Fisica. pp. 433–444. 65. R. H. Tykot, J. Staller. (2002). The importance of early maize agriculture in Coastal Ecuador: New data from La Emerciana. Current Anthropology, 43, 666–677. 66. M. Zárate. (2002). Los ambientes del tardiglacial y Holoceno en Mendoza. In: A. Gil, G. Neme, (Eds.), Entre montañas y desiertos: Arqueología del sur de Mendoza. Buenos Aires, Argentina: Sociedad Argentina de Antropología. pp. 9–42.

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16 Dietary Variation and Prehistoric Maize Farming in the Middle Ohio Valley DIANA M. GREENLEE Department of Anthropology, University of Washington, Seattle, Washington

Introduction 215 Late Woodland and Late Prehistoric Subsistence Records 217 Theory and Method 217 The Isotope Record of Dietary Change 220 Geographic Variation in Maize-Based Farming Systems 222 Conclusions 229

varied both geographically and temporally; initial efforts to account for this variation are summarized.

INTRODUCTION The archaeological record of eastern North America shows substantial temporal and geographic variation in the composition of prehistoric maize-dominated subsistence systems. Geographically, one could choose any of several subareas of the East as the setting for detailed research into why maize-based subsistence systems appeared when and where they did and in the forms they did. The archaeological record of the middle Ohio River valley is particularly appealing in this regard because of the apparent rapidity and degree to which maize came to dominate subsistence systems there. In addition, with stable carbon isotope ratios for more than 370 individuals from 49 occupations, dietary data are sufficiently dense to allow examination of intercommunity variation in middle Ohio Valley maize consumption through time and across space. The study area (Figure 16-1) covers a large portion of the hydrological territory of the Ohio River. The character of the landscape throughout this area is highly variable, ranging from broad floodplains to constricted bottoms along tributary streams, from rolling uplands to narrow snaking ridges, and from mild to substantial topographic relief [19, 37]. Importantly, physiography influences several variables (e.g., local climate, ecology, soils, amount of land available for settlement and/or cultivation) that can impact the structure and content of local subsistence systems. Subsistence and settlement systems varied substantially over the 12,000–13,000 years or so [15] of documented human occupation in the middle Ohio Valley, and it is becoming clear that traditional developmental schemes cannot account for that record. Models that rely on gradual,

Glossary Catchment The area surrounding a settlement that is exploited for resources. Catchment analysis involves determining the distance individuals travel to obtain resources and the distribution of those resources within that territory. Because they differ in terms of their return rates, different resources will be exploited in catchment territories of different size. Diet The consumption of resources by an individual. Subsistence system A subsistence system is the set of activities by means of which resources, both edible and inedible, are acquired by a group of people. Stable carbon isotope analysis of collagen derived from archaeological human skeletal remains is a useful way to track dietary variation associated with the appearance and spread of maize-dominated subsistence systems in inland eastern North America. The isotopic record of the middle Ohio Valley is well suited for examining the trajectory of dietary change associated with the spread of maize farming in the region. The earliest maize-based subsistence systems in the Ohio Valley appear abruptly ca. AD 900. Dietary change (when and where it happened) occurred rapidly—on the order of a generation or so. Following the establishment of maize-based farming systems in the region, isotopic diet

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FIGURE 16-1 The middle Ohio Valley in eastern North America. Archaeological locales with δ13C data, listed in Table 16-1, are shown. Symbol fill indicates data source: black, all data generated by the author; gray, some data generated by the author, some by others; white, all data generated by others.

Dietary Variation and Prehistoric Maize Farming in the Middle Ohio Valley

directional change in settlement or subsistence are inadequate in the face of accumulating archaeological data [cf. 27]. The settlement record, for example, shows an apparent oscillating cycle of community dispersion and nucleation throughout Ohio Valley prehistory [14] rather than a gradual, or progressive, increase in the size and complexity of settlements as is often assumed. With respect to the subsistence record, archaeologists tend to assume a gradual transition from foraging to farming systems as populations incrementally replaced their wild resources with cultivated crops. We cannot yet say if this was how indigenous cultivated plants were integrated into Ohio Valley foraging systems, but the subsequent appearance of maize-based farming systems appears to have been more abrupt [29]. It is the latter subsistence change that is of interest here. Even though maize fragments in the Ohio Valley have been dated directly to ca. AD 330 [21], they do not appear in substantial frequencies in archaeobotanical assemblages until the end of the Late Woodland (AD 400–1000) period [74]. After that, maize continued to be a significant, if not the major, contributor to Late Prehistoric (AD 1000–1650) archaeobotanical assemblages in the Ohio Valley [55, 70]. Thus, if we seek to examine dietary variation associated with the appearance and spread of specialized maize-based farming systems in the Ohio Valley, relevant samples must come from the Late Woodland and Late Prehistoric periods.

LATE WOODLAND AND LATE PREHISTORIC SUBSISTENCE RECORDS Early Late Woodland archaeobotanical assemblages of the middle Ohio Valley are consistent with a generalized subsistence system [29]. They contain remains from the Eastern Agricultural Complex (EAC) plants (goosefoot [Chenopodium berlandieri], maygrass [Phalaris caroliniana], erect knotweed [Polygonum erectum], sunflower [Helianthus annuus], sumpweed [Iva annua], and little barley [Hordeum pusillum]), along with cucurbits and a diverse assortment of wild plant resources, particularly nuts, and occasionally maize [72, 74, 75]. By the end of the Late Woodland period, maize had largely supplanted the native crops and wild plant resources in some archaeobotanical assemblages [69, 70, 74]. Faunal remains are dominated by white-tailed deer, although many other taxa (e.g., elk, bear, turkey, raccoon, rabbit, and squirrel) are represented as well [6, 50]. Late Prehistoric archaeobotanical assemblages, dominated as they are by maize remains, reflect more specialized subsistence systems than Late Woodland ones [29]. Maize ubiquity is high, nuts and fruits remain fairly ubiquitous, and the average ubiquity of EAC plants is lower in most Late

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Prehistoric assemblages than in preceding Late Woodland assemblages [28]. Beans, squash, sunflower, and chenopod are minor contributors [54, 70]. This stands in contrast to some other regions of the East (e.g., the central Mississippi River valley), where cultivated native plants continued to contribute significantly to assemblages even after maize was a staple crop. Late Prehistoric faunal exploitation differed subtly from the Late Woodland period, with increased frequencies of wild turkey and opossum presumably reflecting habitat changes associated with maize farming [28, 29]. Even though successful maize farming systems established an artificial ecology known as a maize agroecology, subsistence systems still mirrored subtleties of the local context.

THEORY AND METHOD Theoretical Framework Evolutionary theory provides a useful framework for explaining why subsistence systems changed as they did [30, 35, 53, 73]. From this perspective, the differential success of particular subsistence alternatives is explained as a product of natural selection. A subsistence adaptation that significantly increases individual fitness spreads at a greater rate than one that marginally increases it. Accordingly, the rapid replacement of a generalized foraging subsistence adaptation by a specialized farming one would indicate that the latter provided a significant advantage to individuals. An “engineering analysis” can establish under what conditions and in what ways one variant is better than another. Archaeologists who balk at the use of evolutionary theory to account for the trajectories of cultural phenomena often cite what they see as two problems: (1) that evolutionary theory cannot account for the distribution of variants that are not genetically transmitted, and (2) that evolutionary theory denies “cultural selection” or human intention as playing an explanatory role. Evolutionary archaeologists [e.g., 16, 53] take a broader view of evolution than those who adhere to a strict biological formulation, and at the same time, they regard people, like other organisms, as subject to evolutionary processes. Thus, evolutionary archaeologists do not see either of these issues as particularly problematic. With respect to the first issue, transmission, evolutionary theory requires heritable variants, but it does not specify a particular means of transmission. (Recall that Darwin formulated the theory in the absence of knowledge regarding the principles of genetic inheritance.) Cultural transmission (i.e., learning) is a potentially significant source of change (perhaps more so than genetic transmission) because learning occurs more or less continuously, involves considerably more organisms, and has fewer biological constraints (e.g., reproductive life span). Through learning, variants may

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spread more widely and more rapidly than through biological reproduction. To the extent that any variant affects behavior (a component of an individual’s phenotype), it is subject to natural selection [45]. The notion of “replicative success” [44] describes the differential spread of variants without regard to how they are transmitted—a variant that presents a greater advantage relative to other variants, no matter how it is transmitted, is transmitted with greater frequency. The second issue is why evolution does not give explanatory power to “cultural selection” or human intention. Does our ability to solve problems guide evolution? No. Certainly, we (and other animals) make what we believe are informed decisions, and we hope for favorable outcomes, but things do not always turn out the way we intend. We cannot always predict the ultimate consequences of our actions. Indeed, we can probably all think of cases where the outcome was not what we intended (e.g., thalidomide use by pregnant women relieved morning sickness but also produced severe birth defects and high early mortality rates among resulting “thalidomide babies”; tube wells in Bangladesh and West Bengal, India, reduced the transmission of waterborne diseases, but they also produced a potentially worse problem— extremely high rates of arsenicosis, or arsenic poisoning). If the outcome of an action bears no relation to the underlying intent, intention cannot be used in an explanatory role. What is important, though, is that some behaviors, regardless of underlying intentions, increase the replicative fitness of their practitioners under some conditions, whereas others do not.

Generating Dietary Data Questions about variation in the dietary consumption of maize by people in inland eastern North America are best addressed through the analysis of stable carbon isotopes of human skeletal tissues. Indeed, dietary data have been generated using collagen from archaeological human bones from Ohio Valley locales for more than 25 years (Table 16-1). Changes in extraction protocols, isotope measurement technology, and sample quality evaluation over the years have undoubtedly introduced some variation in these data, however any errors do not appear to be systematic [28]. Many of the stable isotope data used here were generated as part of the author’s dissertation.a Several variables (collagen a For each individual, two collagen samples were independently extracted and analyzed. The collagen extraction protocol involved mechanical cleaning of the bone, followed by dissolution of the mineral fraction in dilute acid (0.25 M HCl); the demineralized bone was gelatinized in slightly acidic hot water (0.01 M HCl), filtered, and freeze-dried [9, 28]. Although some researchers recommend a NaOH soak as part of the extraction protocol, tests indicate that this step does not produce significantly different results among a sample of these Ohio Valley individuals [28]. Ten mg of collagen extract were weighed into a clean Vycor boat along with manganese dioxide, copper oxide, and silver wire. Each boat was placed

extract yield, carbon and nitrogen concentrations, elemental C/N, amino acid composition) indicate that the protein fraction of these middle Ohio Valley archaeological human skeletal samples generally is well preserved, and thus extracted collagen δ13C values should reflect biological levels at the time of death. Experimental data on rodents [2, 67] indicate that the stable carbon isotopic composition of extracted collagen varies more closely with the isotopic composition of dietary protein (r = 0.774; p = 0.001) than with the whole diet (r = 0.656; p = 0.008). Because maize is a relatively low protein food, its contribution to the overall diet is likely to be underrepresented by the isotopic composition of collagen. This observation has two implications for studies of stable carbon isotopic diet that use collagen. First, collagen δ13C values show clearly when maize came to dominate the diet, but they are less sensitive for tracking the trajectory of low-level maize use before then. Second, although qualitative differences in diet among individuals may be identified, quantitative reconstructions of maize consumption (i.e., the percentage of maize contributed to the diet) based on collagen δ13C values are not appropriate. Although the isotopic composition collagen is most closely reflective of dietary protein, it is important to note that in diets not characterized by nutritionally or isotopically extreme conditions (i.e., in the kinds of diets one might find among free-range organisms), collagen appears to reflect the isotopic composition of the whole diet rather well. The collagen–diet relationship is further improved when one recognizes that the range of potential diets in a “natural” setting is more limited than in experimental ones (e.g., in eastern North America, the probability of diets with C4 protein and C3 carbohydrate bases is quite low). Figure 16-2 shows δ13C values obtained from controlled feeding experiments with rodents and pigs consuming diets that are both nutritionally adequate and within the range of diets consumed prehistorically in the Ohio Valley. The diet–tissue relationship is strongly significant (r = 0.941; p < 0.001). Thus, in a “natural” setting like the Eastern Woodlands, the isotopic composition of bone collagen should reflect the isotopic composition of the whole diet.

in a clean Vycor ampule, evacuated, and sealed before being combusted at 900°C for one hour. Carbon dioxide in the combusted samples was purified cryogenically before isotopic measurement on a Micromass 903 mass spectrometer in the Quaternary Isotope Laboratory, University of Washington. Unlike current generation mass spectrometers, which obtain simultaneously δ13C and δ15N values, this mass spectrometer was not configured to measure 15N/14N ratios. The mean difference (±1 SD) in δ13C values between each pair of archaeological replicates in the dissertation is −0.015 ± 0.015‰. When the measurements of a pair of replicates differed by more than 0.25‰, a third extraction was obtained; a third extract was necessary for 27 of the 251 individuals analyzed in the dissertation (23 of the 177 individuals included in this paper).

Dietary Variation and Prehistoric Maize Farming in the Middle Ohio Valley

TABLE 16-1 Middle Ohio Valley Archaeological Deposits with δ13C Data on Archaeological Human Bone, Estimated Calendrical Age, Number of Individuals Analyzed, Average δ13C Values, and References from Which the Dietary Data are Obtained Name

Calendrical age range (plotted agea)

n

d13C mean ± 1 SD

References

Anderson village

AD 1220–1380 (AD 1280)

8

−10.63 ± 0.21

28

Baldwin

AD 1290–1400 (AD 1340)

2

−12.38 ± 0.17

28

Barker’s Bottomb

(AD 1270) (AD 1450)

1 1

−12.04 −16.13

Robert F. Maslowski, p.c.

Baum

AD 1000–1250 (AD 1100)

10

−12.51 ± 3.11

Buckner

AD 1350–1500 (AD 1400)

8

−9.41 ± 0.84

56

Bunnel Kame

(AD 1360) (AD 1410)

1 1

−18.30 −13.94

28

Campbell Island

AD 1330–1490 (AD 1430)

3

−16.15 ± 3.65

28

28, 57

Capitol View

AD 1350–1550 (AD 1410)

2

−11.10 ± 2.24

56

Childersb

AD 800–1100 (AD 1000)

7

−15.07 ± 3.81

Robert F. Maslowski, p.c., 28

Chilton

AD 130–320 (AD 240)

8

−21.03 ± 0.48

28

C. L. Lewis

390–200 BC (300 BC)

16

−20.69 ± 0.09

28

Cleek-McCabe

AD 1050–1280 (AD 1220)

2

−10.45 ± 0.60

28

Continental Constructionb

AD 720–990 (AD 890)

1

−20.66

28

Cramer

AD 1000–1250 (AD 1125)

3

−14.29 ± 5.37

28

Edwin Harness

(AD 400)

3

−22.67 ± 1.45

3

DuPont

(2500 BC)

10

−21.8 ± 0.93

68

Enos Holmes Mound

AD 1020–1200 (AD 1120)

8

−10.81 ± 0.65

28

Feurt

AD 1250–1400 (AD 1325)

22

−10.87 ± 1.02

28, 57

Gartner

AD 1000–1250 (AD 1150)

15

−11.77 ± 2.65

57

Guard

AD 1060–1260 (AD 1200)

15

−9.35 ± 0.74

28

Hardin Village

AD 1450–1650 (AD 1600)

50

−11.64 ± 0.92

7

Hawkins Ridge

AD 780–980 (AD 890)

2

−20.41 ± 0.05

28

Henderson Mound #2

AD 380–560 (AD 440)

2

−20.39 ± 0.07

28

Hobson

AD 1100–1200 (AD 1150)

1

−9.89

28

Horseshoe Johnson

AD 1220–1280 (AD 1270)

1

−15.76

28

Incinerator

AD 1200–1400 (AD 1300)

39

−11.11 ± 0.61

Killen

AD 1100–1400 (AD 1300)

14

−9.22 ± 0.95

12, 57 28

Larkin

AD 1440–1640 (AD 1490)

3

−9.97 ± 0.47

56

Man

AD 1440–1600 (AD 1480)

6

−9.95 ± 0.79

5

Newtown Firehouse

AD 990–1100 (AD 1020)

4

−20.40 ± 0.13

28

O. C. Voss

AD 1000–1280 (AD 1250)

6

−11.22 ± 1.04

28

Oglesby-Harris

AD 1040–1260 (AD 1170)

1

−19.04

28

Proctor Rockshelter

AD 400–1000 (AD 800)

1

−20.12

28

Riker

AD 1400–1650 (AD 1460)

4

−13.40 ± 0.85

28

Roseberry Farm

AD 1000–1300 (AD 1170)

5

−11.08 ± 1.77

25

Sand Ridge

(1500 BC)

2

−21.00 ± 0.57

28, 68

(Continued)

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TABLE 16-1 (continued) Calendrical age range (plotted agea)

n

d13C mean ± 1 SD

Schomaker

AD 1280–1450 (AD 1370)

1

−12.07

28 3

Name

References

Seip

(AD 325)

5

−22.06 ± 1.03

Slone

AD 1350–1550 (AD 1440)

17

−9.77 ± 0.86

7, 28

State Line

AD 1210–1380 (AD 1280)

9

−9.21 ± 0.55

28

Turpin

AD 540–980 (AD 960) AD 1050–1280 (AD 1210)

16 25

−15.46 ± 5.21 −10.49 ± 1.46

Uffermanb

1410–1270 BC (1350 BC)

1

−20.11

28

Watson

AD 1000–1250 (AD 1150)

1

−10.28

28

Wood-73

AD 980–1200 (AD 1020)

1

−19.04

28

W. S. Cole

AD 890–990 (AD 930)

2

−11.45 ± 1.27

28

Zencor

AD 540–960 (AD 690)

14

−20.17 ± 0.13

28

28, 68

a

Age assigned for plotting purposes, see [28] for discussion regarding establishment of chronological values. b The human burials were apparently deposited more recently than the bulk of the occupational debris at Childers, Continental Construction, and Barker’s Bottom, and burials were apparently deposited earlier than the bulk of the occupational debris at Ufferman.

FIGURE 16-2 Collagen δ13C data versus whole diet for rats [2], mice [67], and pigs [2, 28, 32, 67]. Diets shown here are both nutritionally adequate and within the range one might expect to find in inland eastern North America.

THE ISOTOPE RECORD OF DIETARY CHANGE The first collagen δ13C evidence for significant maize consumption in the middle Ohio River valley dates to roughly AD 900 (Figure 16-3), 600 years or so after its first known appearance in the region. Thus, the several-hundredyear “gap” between the first documented presence of maize remains and maize’s domination of subsistence systems seen in the archaeobotanical record is also apparent in the stable isotope record. (Again, because the isotopic composition of collagen is a product primarily of protein consumption, collagen δ13C values may not reflect low levels of maize consumption prior to maize becoming a major contributor to the diet.) This is a common, as yet largely unexplained,

feature of the subsistence record in many areas of the East [35, 64]. Although it is commonly assumed by archaeologists that dietary change occurs through incremental increases in the consumption of particular resources through time, there is no evidence for a gradual increase in maize intake in the Ohio Valley [29]. When it occurred, subsistence specialization appears to have happened quite abruptly, presumably within a generation or so. That is, there was no gradual “transition” from a subsistence system based on hunting– collecting–gardening of EAC plants to one based on maize farming. I do not imply that the entire population of the region changed its diet within one generation, but wherever and whenever that dietary change occurred, it did so rapidly. This did not happen everywhere in the East; the isotopic record of southern Ontario [34, 40, 58], for example, is more consistent with a gradual increase in maize consumption through time. Jane E. Buikstra [10] has previously observed regional differences in the trajectories of maize-based diets in North America. She found, for instance, that the incorporation of maize into the diets of groups from the Nashville Basin of Tennessee and the Ohio Valley was more rapid and extreme than it was for groups from Ontario or Missouri. Although Buikstra did not offer a specific reason for why dietary change was more rapid in some areas than in others, she implied that it may reflect the variety of maize used (i.e., rapid dietary changes might be associated with the introduction of a new, presumably better-adapted variety of maize into those areas). In contrast, Robert C. Dunnell and I hypothesize that variation of dietary change may be explained by a combination of ecological conditions and pre-existing agricultural technologies [17].

Dietary Variation and Prehistoric Maize Farming in the Middle Ohio Valley

221

FIGURE 16-3 Stable carbon isotope record for the middle Ohio Valley.

Multiple Populations?

Recent Efforts to Account for Dietary Change

Probably of equal interest to the observation that there is no evidence for a gradual “transition” to maize-based farming systems in the Ohio Valley is the apparent long-term continuance of a small population with little or no dietary commitment to maize. Whenever these individuals have been encountered previously in Late Prehistoric contexts [e.g., 57], they were assumed to be associated with earlier occupations at those locales. Although not all of the “relatively late, relatively isotopically depleted (