On the Origin of Species (Knickerbocker Classics) 1631064266, 9781631064265

Citation preview

ON

THE

ORIGIN

OF

SPECIES

ON

THE

ORIGIN

OF

CHARLES DARWIN

SPECIES

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© 2017 by Quarto Publishing Group USA Inc. First published in 2017 by Race Point Publishing, an imprint of The Quarto Group, 142 West 36th Street, 4th Floor, New York, NY 10018, USA T (212) 779-4972 F (212) 779-6058 www.QuartoKnows.com All rights reserved. No part of this book may be reproduced in any form without written permission of the copyright owners. All images in this book have been reproduced with the knowledge and prior consent of the artists concerned, and no responsibility is accepted by producer, publisher, or printer for any infringement of copyright or otherwise, arising from the contents of this publication. Every effort has been made to ensure that credits accurately comply with information supplied. We apologize for any inaccuracies that may have occurred and will resolve inaccurate or missing information in a subsequent reprinting of the book. Race Point titles are also available at discount for retail, wholesale, promotional, and bulk purchase. For details, contact the Special Sales Manager by email at [email protected] or by mail at The Quarto Group, Attn: Special Sales Manager, 401 Second Avenue North, Suite 310, Minneapolis, MN 55401, USA. 10 9 8 7 6 5 4 3 2 1 ISBN: 978-1-63106-426-5 Digital edition: 978-0-76036-139-9 Softcover edition: 978-1-63106-426-5 Editor: Milton Creek Editorial Services Cover Design: Phil Buchanan Cover Pattern: Amy Ormond Printed in China

CONTENTS

introduction to the new edition

vii

introduction

xv

an historical sketch i. variation under domestication

xxi 1

ii. variation under nature

35

iii. struggle for existence

50

iv. natural selection

68

v. laws of variation

116

vi. dificulties on theory

152

vii. instinct

185

viii. hybridism

219

ix. on the imperfection of the geological record

249

x. on the geological succession of organic beings

279

xi. geographical distribution

310

xii. geographical distribution—continued

344

xiii. mutual afinities of organic beings: morphology: embryology: rudimentary organs

370

xiv. recapitulation and conclusion

414



glossary

443



endnotes

462



the life and times of charles darwin

464



further reading

468

INTRODUCTION

TO THE

NEW EDITION

Charles Darwin’s On the Origin of Species, published in England in 1859, was written for the non-specialist and attracted considerable attention upon its publication. Presenting a variety of evidence for the theory of natural selection, the book generated passionate discussions among scientists, clergymen, philosophers, and the general public. Its first edition—the 1,250 copies of which sold out immediately for 15 shillings a print—was followed by five more editions in Darwin’s life. During that time, many corrections and revisions were incorporated into the text as replies to counterarguments and objections from scientists and clergymen. Based on Darwin’s lifelong research in botany, zoology, and geology, the book’s depth and breadth make it important to anyone interested in the development of the scientific and philosophical ideas that shaped the twentieth century, and in particular the life sciences. The namesake for evolution, On the Origin of Species drew a lot of attention outside Britain, especially in the US, and so far has been translated into twenty-seven languages. It has also generated many cultural memes, including the famous term “survival of the fittest” (coined by Herbert Spencer after reading Darwin’s book and introduced in 1869 to the book’s fifth edition) and the equally famous vii

viii F INTRODUCTION TO THE NEW EDITION

illustration The March of Progress (drawn by Rudolph Zallinger for the 1965 Time-Life book Early Man). “A man who dares to waste one hour of time has not discovered the value of life,” said the father of evolutionary biology, his own life exemplifying the truth in those words. Born in 1809 in Shrewsbury, England, to a wealthy family whose members included the abolitionist Erasmus Darwin and the entrepreneur Josiah Wedgwood, Charles Robert Darwin showed a taste for natural history from early childhood. Following his physician father, Darwin enrolled in the University of Edinburgh Medical School, at that time the best in England, but to the annoyance of his father, quickly found the lectures uninteresting and the surgeries stressful, and so neglected his coursework. As a result, his father sent him to Christ’s College, Cambridge, to become a parish priest. There, Darwin was exposed to the ideas of William Paley, the English clergyman known for his views on teleology and natural theology (and in particular, the argument for a divine design in nature); the writings of John Herschel, the natural philosopher; and the works of Alexander von Humboldt, the scientist traveler. After graduating Cambridge, Darwin planned to embark on his own career as a priest naturalist by setting off to Tenerife with his classmates to study the natural history of the tropics, but his plan was soon modified. In late summer 1831 he received a letter from his Cambridge mentor and friend, the botanist John Henslow, who recommended him to Captain Robert Fitzroy. Fitzroy was preparing the HMS Beagle for a two-year journey around the world, and Darwin’s (unpaid) post was designated as the ship’s naturalist. Darwin’s father objected to the trip, which he considered a waste of time, but his brother-in-law, Josiah Wedgwood, convinced him to give his blessing (and the funding) for it. After delays, the journey began in December 1831. It lasted almost five years, and aboard that ship the seeds for On the Origin of Species were sowed.

INTRODUCTION TO THE NEW EDITION f ix

During the long voyage, which he documented in a journal (the journal was later shortened to become another best seller of that time, Voyage of the Beagle, published in 1839), Darwin made patient observations on geology, zoology, botany, and many other events and sceneries he witnessed in Patagonia, the Galapagos Islands, and Australia. These observations—in particular, the delicate differences in beaks between different types (now known as species) of finches in the Galapagos Islands; the fossils of giant Armadillo (glyptodontines) and their resemblance to modern armadillos; and the difference between the Patagonian Rhea (nandu in Guarani, the local preColombian language) and the previously described species—slowly led Darwin into the idea that species might not be fixed, but could change. This view contradicted contemporary beliefs shared by natural theologians and naturalists, according to which each species was fixed and unchangeable because it represented an idea in the mind of the creator, or was created for a specific purpose. The circumstances under which such changes could occur seem to have dawned on Darwin two years following his return to England, after he read Thomas Malthus’s An Essay on the Principle of Population, which was first published anonymously in 1798. In this essay Malthus argues that from a statistical standpoint, human populations, if unrestrained, breed beyond their means and struggle to survive. Connecting these ideas with the description of the world of plants as a constant war (due to Darwin’s contemporary, the botanist Candolle), Darwin seems to have established the following consequence on September 28, 1838, in his notebook On Transmutation of the Species: The final cause of all this wedging, must be to sort out proper structure, & adapt it to changes.—to do that for form, which Malthus shows is the final effect (by means however of volition) of this populousness on the energy of man. One may say there

x F INTRODUCTION TO THE NEW EDITION

is a force like a hundred thousand wedges trying [to] force every kind of adapted structure into the gaps in the economy of nature, or rather forming gaps by thrusting out weaker ones. This “force” would become natural selection, but it would take almost twenty years to spell out the theory and to publish it. In hindsight, the voyage of the Beagle transformed Darwin from a young man adrift into a scientific celebrity. He remains so today, on a par with other scientific giants such as Einstein and Newton. His portrait has become a cultural icon, and his theory of evolution stands at the basis of the life sciences. The theory has also left its cradle, and evolutionary explanations are now common in many domains outside the life sciences, including economics, game theory, cognitive science, and even the social sciences and humanities. What makes evolution so compelling are the basic and simple inferences and facts it rests on, which were explained and defended in On the Origin of Species. At the basis of the theory are several observations, made by Darwin during his voyage, which—together with additional facts he collected in England, and sound logical inferences—portray natural selection as a driving force behind the speciation of living organisms on earth. Today we know of additional mechanisms that contribute to this process, such as genetic drift and mutation, but these additions do not change the basic tenets of the theory as conceived by Darwin, namely, that from an evolutionary perspective, all that an individual organism can do during its lifetime is (1) either live long enough to reproduce and bring about offspring, or (2) die beforehand. Add this simple fact to the observation that in a given area resources (food, water, space), as well as the population size remain roughly constant, and you get a struggle for survival among individual organisms, brought upon by the constraints that the limited resources impose on their (potentially limitless) reproduction. And since not all individual organisms are

INTRODUCTION TO THE NEW EDITION f xi

identical and variation exists among them, those more suited (or more adapted) to the environmental constraints can survive long enough to reproduce and leave their heritable traits to future generations. In On the Origin of Species Darwin named this process natural selection and suggested that, through this process, life on earth (all existing animals and plants) has developed from one ancestor many years ago. It is quite remarkable that Darwin postulated two of the key theoretical elements in his theory long before empirical evidence for them was discovered. The underlying mechanisms for variation between individual organisms and the heritability of these variations—known today thanks to molecular biology to be the result of mutation and transcription of genetic information encoded in the DNA—were completely unknown to Darwin and his contemporaries. The laws of heritability were stated by Gregor Mendel (father of Mendelian genetics) only in 1865 and were later rediscovered in the twentieth century, and the central dogma of molecular biology (that DNA makes RNA, which, in turn, makes proteins, hence the sequential transfer of information) was stated as such only in 1958 by Francis Crick. But Darwin’s keen eye for observing natural phenomena and his collection of facts from his travels allowed him to bridge the gap between theory and evidence, and to turn biology upside down with a stroke of genius in 1859. Darwin was not alone in his ideas. Long before him many had proposed mechanisms for the succession of species and the variation between and among them. Lamarck (1744–1829), a French naturalist, supported a teleological view by which an organism passes traits it has acquired during its lifetime to its offspring. Many German biologists suggested that predetermined rules of development, similar to the development of embryos, guided this succession. But the one who came closest to Darwin, and may have even preceded him, was Alfred Russel Wallace (1823–1913).

xii F INTRODUCTION TO THE NEW EDITION

Like Darwin, Wallace did extensive fieldwork as a naturalist, in his case in the Amazon basin and the Malay Archipelago, and was considered an authority on the geographical distribution of species. His intuitions about evolution and natural selection are evident in papers he published in the early 1850s. These papers caught the eyes of two of Darwin’s acquaintances, Charles Lyell and Edward Blyth, who brought them to Darwin’s attention, and urged him to publish his book to establish priority. Correspondence between Darwin and Wallace, and in particular a draft of a paper Wallace sent Darwin in 1858, shows that the two naturalists were thinking alike and reaching the same conclusions. Darwin, however, had already been working on his book for several years at that point, and had enjoyed social and scientific stature far greater than Wallace. In effect, Darwin was instrumental in getting Wallace’s paper read at the Linnean Society of London in 1858, and some historians argue that without Darwin, Wallace’s views would not have been taken seriously. As is always the case in matters of scientific priority, the Darwin-Wallace relationship has sparked a controversy among historians of science, but the consensus today is that the arguments for a conspiracy that robbed Wallace of an alleged priority on evolution and natural selection are unconvincing. In many respects, our (sub)species, Homo sapiens sapiens, has by now removed itself from the confluence of natural selection. We are able to control (and nowadays even destroy) our environment and resources, and we are able (albeit not yet allowed by norms and laws) to control our hereditary information flow. Yet Darwin regarded our species as quite insignificant in the great chain of beings, continuous with all other life forms. In another best seller of his time, The Descent of Man, and Selection in Relation to Sex, published in 1871, Darwin spells out his views on the evolution of the human race. The book had many interpretations, and since its publication has contributed to heated debates, still ongoing today, on social Darwinism and eugenics. It is

INTRODUCTION TO THE NEW EDITION f xiii

also one of the sources of the never-ending clash between evolution and religion, and the ideas it proposes have generated no end of political controversy in countries where the separation of religion from public education has put science on trial. As science marches on into the third millennium, we have deepened our understanding of evolution, natural selection, and the molecular mechanisms that underlie variation and the heredity of traits. Thus we have come closer to solving Darwin’s “mystery of mysteries,” which he pointed to in the first paragraph of his introduction to On the Origin of Species—we are closer, but not close enough to solving the separate mystery of the origin of life itself. Darwin’s own opinions on this eternal question may have shifted throughout the years. In the 1861 third edition of On the Origin of Species, he says: “It is no valid objection that science as yet throws no light on the far higher problem of the essence or origin of life.” Darwin iterates his conscious avoidance of tackling the problem in a letter to Joseph Dalton Hooker on March 29, 1863, in which he writes: “It is mere rubbish thinking, at present, of origin of life; one might as well think of origin of matter.” But careful readings of all his texts and letters show that he always regarded the question of the origin of life to be susceptible to scientific inquiry. In an often-cited letter to the same addressee in 1871 he wrote: It is often said that all the conditions for the first production of a living being are now present, which could ever have been present. But if (and oh what a big if) we could conceive in some warm little pond with all sorts of ammonia and phosphoric salts,—light, heat, electricity present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present such matter would be instantly devoured, or absorbed, which would not have been the case before living creatures were formed.

xiv F INTRODUCTION TO THE NEW EDITION

The origin of life—“in some warm little pond”—remains a mystery to the Homo sapiens sapiens, the naked ape who has inherited the earth, but evolution, the process that ensued once life had originated, has become a major building block in our theory of living organisms. Charles Darwin, its author, is central to our understanding of the scientific inquiry that led us to where we are today, and to our awareness of our place in the great chain of life. On the Origin of Species is thus not only an important book for us as scientists, it is also an important book for us as human beings.

Amit Hagar PhD is professor and chair of the Department of History and Philosophy of Science and Medicine, and adjunct professor of intelligent systems engineering at Indiana University, Bloomington. He is the author of Discrete or Continuous: The Quest for Fundamental Length in Modern Physics (Cambridge) and numerous articles on the foundations of physics and computer science. His areas of research span the philosophy of science, the foundation of physics and computer science, and more recently, the biophysical modeling of solid tumors.