Natural inheritance

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NATURAL INHERITANCE BY

SIR FRANCIS GALTON

NATURAL INHERITANCE

BY

FRANCIS GALTON, F.R.S. AUTHOR OF

"llEBEDITARY OENIUS,n "INQUIRIES INTO RUMAN FACULTY," ETC.

CONTENTS. CH.APTER I.

PAGE

1

INTRODUCTORY • . . . . • CH.APTER IT. PROCESSES IN HEREDITY Natural and .Acquired Peculiarities, 4.-Transmutation of Female into Male measures, 5.-Particulate Inheritance, 7.-Family Likeness and Individual Variation, 9.-Latent Characteristics, 11.-Heritages that Blend, and those that are mutually Ex­ clusive, 12.-Inheritance of Acquired Faculties, 14. -Variety of Petty Inflnences, 16.

4

CHAPTER III. ORGANIC STABILITY • • , • • • . • , • • • • • • • • • • • • •

18

Incipient Structure, 18.-Filial Relation, 19.-Stable Forms 20.­ Subordinnte Positions of Stability, 25.-Model, 27.-Stnbility of Spol'-ts, 30,-Infertility of Mixed Types, 31.-Evolution not by Minute Steps only, 32. CH.APTER IV. SCHEMES OF DISTRIBUTION AND OF FREQUENCY Fraternities and Populations to be treated as units, 35.-Schemes of Distribution and their Grade�, 37.-The Shape of Schemes is independent of the number of Observations, 44.-Data for eighteen Schemes, 46.-Application of Schemes to inexact measures, 47.-Schemes of Frequency, 49.

35

CONTENTS.

vi

CHAPTER V. PAOl'J

51

NORMAL VARIABILITY • • •

Scheme of Deviations, 51.-Normal Curve of Distributions, 54.­ Comparison of the Observed with the Normal Curve, 56.--The value of a single Deviation at a known Grade, cletermines a Normal Scheme of Deviations, 60.-Two Measures at known Grades, determine a Normal Scheme of Measures, 61. The Charms of Statistics, 62.-Mechanical Illustration of the Cause of Curve of Frequency, 63.-Order in Apparent Chaos, 66.-­ Problems in the Law of Error, 66. CHAPTER VI.

71

DATA . . • . • • . • .

Records of Family Faculties, or R.F.F. data, 72.-Spechl Data, 78.-Measures at my .Anthropometric Laboratory, 79.-Experi­ ments in Sweet Peas, 79.

CHAPTER VII. DrscUSSION OF THE DATA OF STATURE • • • • . • • • • • • • •

83

Stature as a Subject for Inquiry, 83.-Marriage Selection, 85.­ Issue of Unlike Parents, 88.-Description of the Tables of Statu-re, 91.-Mid-Stature of the Population, 92.-Variability of the Population, 93.-Variability of Mid-Parents, 93.­ Va-riability in Co-Fraternities, 94.-Regression,-a, Filial, 95; b, Mid-Parental, 99; c, Parental, 100; a, Fraternal, JOB.­ Squadron of Statures, 110.-Successive Generations of a People, 115.-Natural Selection, 119.-Variability in Frater­ nities: First Method, 124 ; Second Method, 127; Third Method, 127; Fomth Method, 128; Trustworthiness of the Constants, 130 ; General view of Kinsliip, 132.-Separate Con­ tribution of each Ancestor, 13-t-Pedigree Moths, 136.

CHAPTER

vm.

DIRCUSSION OF THE DATA OF EYE COLOUR

Preliminary Remarks, 138.-Datn, 139.-Persistence of Eye Colour in tl:e Population, 140.-Fundamental Eye Colours, 142.-Principles of Calculation, 148.-Results, 152.

138

CONTENTS.

vii

CHAPTER IX.

PAO'£

THE ARTISTIC FACULTY

154

Data, 154.-Sexual Distribution, 156.- Marriage Selection, 157.­

Regression, 158.--Effect of Bias in Marriage, 162. CHAPTER X. DISEASE • • • • • • • • , • • • • • • • . • . • • . . • • • .

164

Preliminary Problem, 165.-Data, 167.-Trnstworthiness of R.F.F. data, 167.-Mixture of Inheritances, 167.-CoNSUMP­ TION : General remarks, 171 ; Distribution of Fmtcrnitic�, 174; Severely Tainted Fraternities, 176; ConsnmptiYity, 181. -Data for Hereditary Diseases, 185. CHAPTER XI. LATENT

ELEMENTS . . , . . , . . . . . . . . . . . . . . . . 187 Latent Elements not very numerou�, 187 ; Pure Breed, l 89.­ Simplification of Hereditary Inquiry, 190. CHAPTER XU.

SUMMARY

• • . . . . • . . • ]!)2

viii

CONTENTS.

TABLES. The words by which the various Tables are here described, have been chosen for the sake of quick reference ; they are often not identical with those used in their actual heacJings, Nn. of the Tables.

1. 2.

3. 4.

5. 6. 7. 8.

SUBJECTS OF THE TABLES.

PAOE

Strengths of Pull arranged for drawing a Scheme . . . . . Data for Schemes of Distribution for various Qualities and Faculties . . . . . . . . . . . . . . . • . . . . . . Evidences of the general applicability of the Law of Frequency of Error . . . . . . . . . . . . . . . . . • . . . . Values for the Normal Curve of Frequency (extracted from the well-known Table) Values of the Probability Integral (extracted from the wellknown TaLle) . Values of the Probability Integral when the scale by which the Errors are measured has the Prob : Error for its Unit . Ordinates to the Normal Curve of Distribution, when its 100 Grades run from - 50°, through 0°, to + 50� Ditto when the Grades run from 0° to 100°. ( This Table is

199

.

es1Je1·ially adaptedfor use with Schemes)

Marriage Selection i°; respect to Stature 9a. Marriage Selection in respect to Eye Colour . _9b. Marriages of the Artistic and the Non Artistic JO. Issue of Parents who are unlike in Stature 11. Statures of adult children born to Mid Parents of Various Statures l 2. Statures of the Brothers of men of various Statures, from R F.F. data . . . . . . . . . . . . . . . . . 9.

.

200 201 202 202 203 204 205 206 206 207 207 208 209

CONTENTS. No. of the Tables.

13. 14. 15.

16. 17.

SUBJECTS OF 'rHE TABLF.S.

Ditto from the Special data . . . . . . Deviations of Individual brothers from their common Mid­ Fraternal Stature Frequency of the different Eye Colours in 4 successive Generations . . • . • • • • . . . . • . . . . . . . The Descent of Hazel-Eyed families . . . . . • . . Calculated contributions from Parents t1nd from Grandparents, according as they are Light, Hazel, or Dark eyed

ix l'AOE

210 211

212 213

18.

213 Examples of the npplication of Table 17 , . . . . . . . . . 214

19. 20.

Observed and calculnted Eye Colours in 16 groups of families 215 Ditto in 78 separate families . . . . . . . . . . . . . . . 216

21.

Amounts of error in the various calculations of anticipated Eye Colour • . . . • . . . . . 218 Inheritance of the Artistic Faculty . . . . . . . . . . . . 218

22.

APPENDICES. A.

Memoirs and Books on Heredity by the Author

B. Problems by J. D. Hamilton Dickson

c.

Experiments on Sweet Peas, bearing on the law of Regression . D. Good and bad Temper in English Families . E. The Geometric Mean in Vital and Social Statistics. F. Probable extinction of Families, 214 ; Discussion of the Problem by the.Rev. H. W. Watson, D.Sc. G. Orderly arrangement of Hereditary Data •

219 221 225 226 238 241 248

INDEX . . . • . . . • • . . . . . . . . . . . .. . . . . . . 257

NATURAL INHERITANCE

NATURAL INHERITANCE. CHAPTER I. IN T R O D U C T O RY.

I HAVE long been engaged upon certain problems that lie at the hase of the science of heredity, and during several years have published technical memoirs concern­ ing them, a list of which is given in Appendix A. This volume contains the more important of the results, set forth in an orderly way, with more completeness than has hitherto been possible, together with a large amount of new matter. The inquiry relates to the inheritance of moderately exceptional qualities by brotherhoods and multitudes rather than by individuals, and it is carried on by more. refined and searching methods than those usually · employed in hereditary inquiries. One of the problems to be dealt with refers to the curious regularity commonly observed in the statistical peculiarities of great populations during a long series of B

2

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