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Title: Applied Eugenics

Author: Paul Popenoe and Roswell Hill Johnson

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APPLIED EUGENICS

BY

PAUL POPENOE

EDITOR OF THE JOURNAL OF HEREDITY (ORGAN OF
THE AMERICAN GENETIC ASSOCIATION),
WASHINGTON, D. C.

AND

ROSWELL HILL JOHNSON
PROFESSOR IN THE UNIVERSITY OF PITTSBURG

THE MACMILLAN COMPANY NEW YORK ? BOSTON ? CHICAGO ? DALLAS
ATLANTA - SAN FRANCISCO

MACMILLAN & CO. , LIMITED LONDON ? BOMBAY ? CALCUTTA MELBOURNE

THE MACMILLAN CO. OF CANADA, LTD. TORONTO

1918

_All rights reserved_

COPYRIGHT, 1918,

BY THE MACMILLAN COMPANY

Set up and electrotyped. Published October, 1918.




PREFACE


The science of eugenics consists of a foundation of biology and a
superstructure of sociology. Galton, its founder, emphasized both parts
in due proportion. Until recently, however, most sociologists have been
either indifferent or hostile to eugenics, and the science has been left
for the most part in the hands of biologists, who have naturally worked
most on the foundations and neglected the superstructure. Although we
are not disposed to minimize the importance of the biological part, we
think it desirable that the means of applying the biological principles
should be more carefully studied. The reader of this book will,
consequently, find only a summary explanation of the mechanism of
inheritance. Emphasis has rather been laid on the practical means by
which society may encourage the reproduction of superior persons and
discourage that of inferiors.

We assume that in general, a eugenically superior or desirable person
has, to a greater degree than the average, the germinal basis for the
following characteristics: to live past maturity, to reproduce
adequately, to live happily and to make contributions to the
productivity, happiness, and progress of society. It is desirable to
discriminate as much as possible between the possession of the germinal
basis and the observed achievement, since the latter consists of the
former plus or minus environmental influence. But where the amount of
modification is too obscure to be detected, it is advantageous to take
the demonstrated achievement as a tentative measure of the germinal
basis. The problem of eugenics is to make such legal, social and
economic adjustments that (1) a larger proportion of superior persons
will have children than at present, (2) that the average number of
offspring of each superior person will be greater than at present, (3)
that the most inferior persons will have no children, and finally that
(4) other inferior persons will have fewer children than now. The
science of eugenics is still young and much of its program must be
tentative and subject to the test of actual experiment. It is more
important that the student acquire the habit of looking at society from
a biological as well as a sociological point of view, than that he put
his faith in the efficacy of any particular mode of procedure.

The essential points of our eugenics program were laid down by Professor
Johnson in an article entitled "Human Evolution and its Control" in the
_Popular Science Monthly_ for January, 1910. Considerable parts of the
material in the present book have appeared in the _Journal of Heredity_.
Helpful suggestions and criticism have been received from several
friends, in particular Sewall Wright and O. E. Baker of the United States
Department of Agriculture.
PAUL POPENOE.

WASHINGTON, _June, 1918. _




TABLE OF CONTENTS


PAGE

PREFACE v

INTRODUCTION BY EDWARD A. ROSS xi


CHAPTER

I. NATURE OR NURTURE? 1

II. MODIFICATION OF THE GERM-PLASM 25

III. DIFFERENCES AMONG MEN 75

IV. THE INHERITANCE OF MENTAL CAPACITIES 84

V. THE LAWS OF HEREDITY 99

VI. NATURAL SELECTION 116

VII. ORIGIN AND GROWTH OF THE EUGENICS MOVEMENT 147

VIII. DESIRABILITY OF RESTRICTIVE EUGENICS 167

IX. THE DYSGENIC CLASSES 176

X. METHODS OF RESTRICTION 184

XI. THE IMPROVEMENT OF SEXUAL SELECTION 211

XII. INCREASING THE MARRIAGE RATE OF THE SUPERIOR 237

XIII. INCREASE OF THE BIRTH-RATE OF THE SUPERIOR 255

XIV. THE COLOR LINE 280

XV. IMMIGRATION 298

XVI. WAR 318

XVII. GENEALOGY AND EUGENICS 329

XVIII. THE EUGENIC ASPECT OF SOME SPECIFIC REFORMS 352
TAXATION 352
BACK TO THE FARM MOVEMENT 355
DEMOCRACY 360
SOCIALISM 362
CHILD LABOR 368
COMPULSORY EDUCATION 369
VOCATIONAL GUIDANCE AND TRAINING 371
MINIMUM WAGE 374
MOTHER'S PENSIONS 375
HOUSING 376
FEMINISM 378

OLD AGE PENSIONS 384
SEX HYGIENE MOVEMENT 385
TRADES UNIONISM 388
PROHIBITION 389
PEDAGOGICAL CELIBACY 390

XIX. RELIGION AND EUGENICS 393

XX. EUGENICS AND EUTHENICS 402

APPENDIX A. OVARIAN TRANSPLANTATION 419

" B. DYNAMIC EVOLUTION 421

" C. THE "MELTING POT" 424

" D. THE ESSENCE OF MENDELISM 429

" E. USEFUL WORKS OF REFERENCE 436

" F. GLOSSARY 437




LIST OF ILLUSTRATIONS


FIGURE PAGE

1. Four Baby Girls at Once 6

2. The Effect of Nurture in Changing Nature 10

3. Height in Corn and Men 12

4. Why Men Grow Short or Tall 14

5. Bound Foot of a Chinese Woman 42

6. Defective Little Toe of a Prehistoric Egyptian 42

7. Effect of Lead as a "Racial Poison" 63

8. Distribution of 10-Year-Old School Children 76

9. Variation in Ability 77

10. Origin of a Normal Probability Curve 78

11. The "Chance" or "Probability" Form of Distribution 79

12. Probability Curve with Increased Number of Steps 80

13. Normal Variability Curve Following Law of Chance 80

14. Cadets Arranged to Show Normal Curve of Variability 82

15. Variation in Heights of Recruits to the American Army 82

16. How Do You Clasp Your Hands? 100

17. The Effect of Orthodactyly 102

18. A Family with Orthodactyly 102

19. White Blaze in the Hair 104

20. A Family of Spotted Negroes 104

21. A Human Finger-Tip 106

22. The Limits of Hereditary Control 106

23. The Distribution of Intelligence 106

24. The Twins whose Finger-Prints are Shown in Fig. 25 108

25. Finger-Prints of Twins 110

26. A Home of the "Hickory" Family 168

27. A Chieftain of the Hickory Clan 170

28. Two Juke Homes of the Present Day 172

29. Mongolian Deficiency 174

30. Feeble-Minded Men are Capable of Much Rough Labor 192

31. Feeble-Minded at a Vineland Colony 192

32. How Beauty Aids a Girl's Chance of Marriage 215

33. Intelligent Girls are Most Likely to Marry 216

34. Years Between Graduation and Marriage 217

35. The Effect of Late Marriages 218

36. Wellesley Graduates and Non-Graduates 242

37. Birth Rate of Harvard and Yale Graduates 266

38. Families of Prominent Methodists 263

39. Examining Immigrants at Ellis Island, New York, 303

40. Line of Ascent that Carries the Family Name 331

41. The Small Value of a Famous, but Remote, Ancestor 338

42. History of 100 Babies 344

43. Adult Morality 345

44. Influence of Mother's Age 347

45. The "Mean Man" of the Old White American Stock 425

46. The Carriers of Heredity 431




INTRODUCTION


The Great War has caused a vast destruction of the sounder portion of
the belligerent peoples and it is certain that in the next generation
the progeny of their weaker members will constitute a much larger
proportion of the whole than would have been the case if the War had not
occurred. Owing to this immeasurable calamity that has befallen the
white race, the question of eugenics has ceased to be merely academic.
It looms large whenever we consider the means of avoiding a stagnation
or even decline of our civilization in consequence of the losses the War
has inflicted upon the more valuable stocks. Eugenics is by no means
tender with established customs and institutions, and once it seemed
likely that its teachings would be left for our grandchildren to act on.
But the plowshare of war has turned up the tough sod of custom, and now
every sound new idea has a chance. Rooted prejudices have been leveled
like the forests of Picardy under gun fire. The fear of racial decline
provides the eugenist with a far stronger leverage than did the hope of
accelerating racial progress. It may be, then, that owing to the War
eugenic policies will gain as much ground by the middle of this century
as without it they would have gained by the end of the century.

This book could not have been written ten years ago because many of the
data it relies on were not then in existence. In view of inquiries now
going on, we may reasonably hope that ten years hence it will be
possible to make a much better book on the subject. But I am sure that
this book is as good a presentation as can be made of eugenics at its
present stage of development. The results of all the trustworthy
observations and experiments have been taken into account, and the
testing of human customs and institutions in the light of biological
principles tallies well with the sociology of our times.

I cannot understand how any conscientious person, dealing in a large way
with human life, should have the hardihood to ignore eugenics. This book
should command the attention not only of students of sociology, but, as
well, of philanthropists, social workers, settlement wardens, doctors,
clergymen, educators, editors, publicists, Y. M. C. A. secretaries and
industrial engineers. It ought to lie at the elbow of law-makers,
statesmen, poor relief officials, immigration inspectors, judges of
juvenile courts, probation officers, members of state boards of control
and heads of charitable and correctional institutions. Finally, the
thoughtful ought to find in it guidance in their problem of mating. It
will inspire the superior to rise above certain worldly ideals of life
and to aim at a family success rather than an individual success.

EDWARD ALSWORTH ROSS.

The University of Wisconsin
Madison, Wisconsin
July 1918.




APPLIED EUGENICS




CHAPTER I

NATURE OR NURTURE?


At the First Race Betterment Conference held at Battle Creek, Mich. ,
many methods were suggested by which it was believed that the people of
America might be made, on the average, healthier, happier, and more
efficient. One afternoon the discussion turned to the children of the
slums. Their condition was pictured in dark colors. A number of
eugenists remarked that they were in many cases handicapped by a poor
heredity. Then Jacob Riis--a man for whom every American must feel a
profound admiration--strode upon the platform, filled with indignation.

"We have heard friends here talk about heredity," he exclaimed. "The
word has rung in my ears until I am sick of it. Heredity! Heredity!
There is just one heredity in all the world that is ours--we are
children of God, and there is nothing in the whole big world that we
cannot do in His service with it. "

It is probably not beyond the truth to say that in this statement Jacob
Riis voiced the opinion of a majority of the social workers of this
country, and likewise a majority of the people who are faithfully and
with much self-sacrifice supporting charities, uplift movements, reform
legislation, and philanthropic attempts at social betterment in many
directions. They suppose that they are at the same time making the race
better by making the conditions better in which people live.

It is widely supposed that, although nature may have distributed some
handicaps at birth, they can be removed if the body is properly warmed
and fed and the mind properly exercised. It is further widely supposed
that this improvement in the condition of the individual will result in
his production of better infants, and that thus the race, gaining a
little momentum in each generation, will gradually move on toward
ultimate perfection.

There is no lack of efforts to improve the race, by this method of
direct change of the environment. It involves two assumptions, which are
sometimes made explicitly, sometimes merely taken for granted. These
are:

1. That changes in a man's surroundings, or, to use the more technical
biological term, in his nurture, will change the nature that he has
inherited.

2. That such changes will further be transmitted to his children.

Any one who proposes methods of race betterment, as we do in the present
book, must meet these two popular beliefs. We shall therefore examine
the first of them in this chapter, and the second in Chapter II.

Galton adopted and popularized Shakespere's antithesis of _nature_ and
_nurture_ to describe a man's inheritance and his surroundings, the two
terms including everything that can pertain to a human being. The words
are not wholly suitable, particularly since nature has two distinct
meanings,--human nature and external nature. The first is the only one
considered by Galton. Further, nurture is capable of subdivision into
those environmental influences which do not undergo much change,--e. g. ,
soil and climate,--and those forces of civilization and education which
might better be described as culture. The evolutionist has really to
deal with the three factors of germ-plasm, physical surroundings and
culture. But Galton's phrase is so widely current that we shall continue
to use it, with the implications that have just been outlined.

The antithesis of nature and nurture is not a new one; it was met long
ago by biologists and settled by them to their own satisfaction. The
whole body of experimental and observational evidence in biology tends
to show that the characters which the individual inherits from his
ancestors remain remarkably constant in all ordinary conditions to which
they may be subjected. Their constancy is roughly proportionate to the
place of the animal in the scale of evolution; lower forms are more
easily changed by outside influence, but as one ascends to the higher
forms, which are more differentiated, it is found more and more
difficult to effect any change in them. Their characters are more
definitely fixed at birth. [1]

It is with the highest of all forms, Man, that we have now to deal. The
student in biology is not likely to doubt that the differences in men
are due much more to inherited nature than to any influences brought to
bear after birth, even though these latter influences include such
powerful ones as nutrition and education within ordinary limits.

But the biological evidence does not lend itself readily to summary
treatment, and we shall therefore examine the question by statistical
methods. [2] These have the further advantage of being more easily
understood; for facts which can be measured and expressed in numbers are
facts whose import the reader can usually decide for himself: he is
perfectly able to determine, without any special training, whether twice
two does or does not make four. One further preliminary remark: the
problem of nature vs. nurture can not be solved in general terms; a
moment's thought will show that it can be understood only by examining
one trait at a time. The problem is to decide whether the differences
between the people met in everyday life are due more to inheritance or
to outside influences, and these differences must naturally be examined
separately; they can not be lumped together.

To ask whether nature in general contributes more to a man than nurture
is futile; but it is not at all futile to ask whether the differences in
a given human trait are more affected by differences in nature than by
differences in nurture. It is easy to see that a verdict may be
sometimes given to one side, sometimes to the other. Albinism in
animals, for instance, is a trait which is known to be inherited, and
which is very slightly affected by differences of climate, food supply,
etc. On the other hand, there are factors which, although having
inherited bases, owe their expression almost wholly to outside
influences. Professor Morgan, for example, has found a strain of fruit
flies whose offspring in cold weather are usually born with
supernumerary legs. In hot weather they are practically normal. If this
strain were bred only in the tropics, the abnormality would probably not
be noticed; on the other hand, if it were bred only in cold regions, it
would be set down as one characterized by duplication of limbs. The
heredity factor would be the same in each case, the difference in
appearance being due merely to temperature.

Mere inspection does not always tell whether some feature of an
individual is more affected by changes in heredity or changes in
surroundings. On seeing a swarthy man, one may suppose that he comes of
a swarthy race, or that he is a fair-skinned man who has lived long in
the desert. In the one case the swarthiness would be inheritable, in the
other not. Which explanation is correct, can only be told by examining a
number of such individuals under critical conditions, or by an
examination of the ancestry. A man from a dark-skinned race would become
little darker by living under the desert sun, while a white man would
take on a good deal of tan.

The limited effect of nurture in changing nature is in some fields a
matter of common observation. The man who works in the gymnasium knows
that exercise increases the strength of a given group of muscles for a
while, but not indefinitely. There comes a time when the limit of a
man's hereditary potentiality is reached, and no amount of exercise will
add another millimeter to the circumference of his arm. Similarly the
handball or tennis player some day reaches his highest point, as do
runners or race horses. A trainer could bring Arthur Duffy in a few
years to the point of running a hundred yards in 9-3/5 seconds, but no
amount of training after that could clip off another fifth of a second.
A parallel case is found in the students who take a college examination.
Half a dozen of them may have devoted the same amount of time to it--may
have crammed to the limit--but they will still receive widely different
marks. These commonplace cases show that nurture has seemingly some
power to mold the individual, by giving his inborn possibilities a
chance to express themselves, but that nature says the first and last
word.
It is more
important that the student acquire the habit of looking at society from
a biological as well as a sociological point of view, than that he put
his faith in the efficacy of any particular mode of procedure.

The essential points of our eugenics program were laid down by Professor
Johnson in an article entitled "Human Evolution and its Control" in the
_Popular Science Monthly_ for January, 1910. Considerable parts of the
material in the present book have appeared in the _Journal of Heredity_.
Helpful suggestions and criticism have been received from several
friends, in particular Sewall Wright and O. E. Baker of the United States
Department of Agriculture.
PAUL POPENOE.

WASHINGTON, _June, 1918. _




TABLE OF CONTENTS


PAGE

PREFACE v

INTRODUCTION BY EDWARD A. ROSS xi


CHAPTER

I. NATURE OR NURTURE? 1

II. MODIFICATION OF THE GERM-PLASM 25

III. DIFFERENCES AMONG MEN 75

IV. THE INHERITANCE OF MENTAL CAPACITIES 84

V. THE LAWS OF HEREDITY 99

VI. NATURAL SELECTION 116

VII. ORIGIN AND GROWTH OF THE EUGENICS MOVEMENT 147

VIII. DESIRABILITY OF RESTRICTIVE EUGENICS 167

IX. THE DYSGENIC CLASSES 176

X. METHODS OF RESTRICTION 184

XI. THE IMPROVEMENT OF SEXUAL SELECTION 211

XII. INCREASING THE MARRIAGE RATE OF THE SUPERIOR 237

XIII. INCREASE OF THE BIRTH-RATE OF THE SUPERIOR 255

XIV. THE COLOR LINE 280

XV. IMMIGRATION 298

XVI. WAR 318

XVII. GENEALOGY AND EUGENICS 329

XVIII. THE EUGENIC ASPECT OF SOME SPECIFIC REFORMS 352
TAXATION 352
BACK TO THE FARM MOVEMENT 355
DEMOCRACY 360
SOCIALISM 362
CHILD LABOR 368
COMPULSORY EDUCATION 369
VOCATIONAL GUIDANCE AND TRAINING 371
MINIMUM WAGE 374
MOTHER'S PENSIONS 375
HOUSING 376
FEMINISM 378

OLD AGE PENSIONS 384
SEX HYGIENE MOVEMENT 385
TRADES UNIONISM 388
PROHIBITION 389
PEDAGOGICAL CELIBACY 390

XIX. RELIGION AND EUGENICS 393

XX. EUGENICS AND EUTHENICS 402

APPENDIX A. OVARIAN TRANSPLANTATION 419

" B. DYNAMIC EVOLUTION 421

" C. THE "MELTING POT" 424

" D. THE ESSENCE OF MENDELISM 429

" E. USEFUL WORKS OF REFERENCE 436

" F. GLOSSARY 437




LIST OF ILLUSTRATIONS


FIGURE PAGE

1. Four Baby Girls at Once 6

2. The Effect of Nurture in Changing Nature 10

3. Height in Corn and Men 12

4. Why Men Grow Short or Tall 14

5. Bound Foot of a Chinese Woman 42

6. Defective Little Toe of a Prehistoric Egyptian 42

7. Effect of Lead as a "Racial Poison" 63

8. Distribution of 10-Year-Old School Children 76

9. Variation in Ability 77

10. Origin of a Normal Probability Curve 78

11. The "Chance" or "Probability" Form of Distribution 79

12. Probability Curve with Increased Number of Steps 80

13. Normal Variability Curve Following Law of Chance 80

14. Cadets Arranged to Show Normal Curve of Variability 82

15. Variation in Heights of Recruits to the American Army 82

16. How Do You Clasp Your Hands? 100

17. The Effect of Orthodactyly 102

18. A Family with Orthodactyly 102

19. White Blaze in the Hair 104

20. A Family of Spotted Negroes 104

21. A Human Finger-Tip 106

22. The Limits of Hereditary Control 106

23. The Distribution of Intelligence 106

24. The Twins whose Finger-Prints are Shown in Fig. 25 108

25. Finger-Prints of Twins 110

26. A Home of the "Hickory" Family 168

27. A Chieftain of the Hickory Clan 170

28. Two Juke Homes of the Present Day 172

29. Mongolian Deficiency 174

30. Feeble-Minded Men are Capable of Much Rough Labor 192

31. Feeble-Minded at a Vineland Colony 192

32. How Beauty Aids a Girl's Chance of Marriage 215

33. Intelligent Girls are Most Likely to Marry 216

34. Years Between Graduation and Marriage 217

35. The Effect of Late Marriages 218

36. Wellesley Graduates and Non-Graduates 242

37. Birth Rate of Harvard and Yale Graduates 266

38. Families of Prominent Methodists 263

39. Examining Immigrants at Ellis Island, New York, 303

40. Line of Ascent that Carries the Family Name 331

41. The Small Value of a Famous, but Remote, Ancestor 338

42. History of 100 Babies 344

43. Adult Morality 345

44. Influence of Mother's Age 347

45. The "Mean Man" of the Old White American Stock 425

46. The Carriers of Heredity 431




INTRODUCTION


The Great War has caused a vast destruction of the sounder portion of
the belligerent peoples and it is certain that in the next generation
the progeny of their weaker members will constitute a much larger
proportion of the whole than would have been the case if the War had not
occurred. Owing to this immeasurable calamity that has befallen the
white race, the question of eugenics has ceased to be merely academic.
It looms large whenever we consider the means of avoiding a stagnation
or even decline of our civilization in consequence of the losses the War
has inflicted upon the more valuable stocks. Eugenics is by no means
tender with established customs and institutions, and once it seemed
likely that its teachings would be left for our grandchildren to act on.
But the plowshare of war has turned up the tough sod of custom, and now
every sound new idea has a chance. Rooted prejudices have been leveled
like the forests of Picardy under gun fire. The fear of racial decline
provides the eugenist with a far stronger leverage than did the hope of
accelerating racial progress. It may be, then, that owing to the War
eugenic policies will gain as much ground by the middle of this century
as without it they would have gained by the end of the century.

This book could not have been written ten years ago because many of the
data it relies on were not then in existence. In view of inquiries now
going on, we may reasonably hope that ten years hence it will be
possible to make a much better book on the subject. But I am sure that
this book is as good a presentation as can be made of eugenics at its
present stage of development. The results of all the trustworthy
observations and experiments have been taken into account, and the
testing of human customs and institutions in the light of biological
principles tallies well with the sociology of our times.

I cannot understand how any conscientious person, dealing in a large way
with human life, should have the hardihood to ignore eugenics. This book
should command the attention not only of students of sociology, but, as
well, of philanthropists, social workers, settlement wardens, doctors,
clergymen, educators, editors, publicists, Y. M. C. A. secretaries and
industrial engineers. It ought to lie at the elbow of law-makers,
statesmen, poor relief officials, immigration inspectors, judges of
juvenile courts, probation officers, members of state boards of control
and heads of charitable and correctional institutions. Finally, the
thoughtful ought to find in it guidance in their problem of mating. It
will inspire the superior to rise above certain worldly ideals of life
and to aim at a family success rather than an individual success.

EDWARD ALSWORTH ROSS.

The University of Wisconsin
Madison, Wisconsin
July 1918.




APPLIED EUGENICS




CHAPTER I

NATURE OR NURTURE?


At the First Race Betterment Conference held at Battle Creek, Mich. ,
many methods were suggested by which it was believed that the people of
America might be made, on the average, healthier, happier, and more
efficient. One afternoon the discussion turned to the children of the
slums. Their condition was pictured in dark colors. A number of
eugenists remarked that they were in many cases handicapped by a poor
heredity. Then Jacob Riis--a man for whom every American must feel a
profound admiration--strode upon the platform, filled with indignation.

"We have heard friends here talk about heredity," he exclaimed. "The
word has rung in my ears until I am sick of it. Heredity! Heredity!
There is just one heredity in all the world that is ours--we are
children of God, and there is nothing in the whole big world that we
cannot do in His service with it. "

It is probably not beyond the truth to say that in this statement Jacob
Riis voiced the opinion of a majority of the social workers of this
country, and likewise a majority of the people who are faithfully and
with much self-sacrifice supporting charities, uplift movements, reform
legislation, and philanthropic attempts at social betterment in many
directions. They suppose that they are at the same time making the race
better by making the conditions better in which people live.

It is widely supposed that, although nature may have distributed some
handicaps at birth, they can be removed if the body is properly warmed
and fed and the mind properly exercised. It is further widely supposed
that this improvement in the condition of the individual will result in
his production of better infants, and that thus the race, gaining a
little momentum in each generation, will gradually move on toward
ultimate perfection.

There is no lack of efforts to improve the race, by this method of
direct change of the environment. It involves two assumptions, which are
sometimes made explicitly, sometimes merely taken for granted. These
are:

1. That changes in a man's surroundings, or, to use the more technical
biological term, in his nurture, will change the nature that he has
inherited.

2. That such changes will further be transmitted to his children.

Any one who proposes methods of race betterment, as we do in the present
book, must meet these two popular beliefs. We shall therefore examine
the first of them in this chapter, and the second in Chapter II.

Galton adopted and popularized Shakespere's antithesis of _nature_ and
_nurture_ to describe a man's inheritance and his surroundings, the two
terms including everything that can pertain to a human being. The words
are not wholly suitable, particularly since nature has two distinct
meanings,--human nature and external nature. The first is the only one
considered by Galton. Further, nurture is capable of subdivision into
those environmental influences which do not undergo much change,--e. g. ,
soil and climate,--and those forces of civilization and education which
might better be described as culture. The evolutionist has really to
deal with the three factors of germ-plasm, physical surroundings and
culture. But Galton's phrase is so widely current that we shall continue
to use it, with the implications that have just been outlined.

The antithesis of nature and nurture is not a new one; it was met long
ago by biologists and settled by them to their own satisfaction. The
whole body of experimental and observational evidence in biology tends
to show that the characters which the individual inherits from his
ancestors remain remarkably constant in all ordinary conditions to which
they may be subjected. Their constancy is roughly proportionate to the
place of the animal in the scale of evolution; lower forms are more
easily changed by outside influence, but as one ascends to the higher
forms, which are more differentiated, it is found more and more
difficult to effect any change in them. Their characters are more
definitely fixed at birth. [1]

It is with the highest of all forms, Man, that we have now to deal. The
student in biology is not likely to doubt that the differences in men
are due much more to inherited nature than to any influences brought to
bear after birth, even though these latter influences include such
powerful ones as nutrition and education within ordinary limits.

But the biological evidence does not lend itself readily to summary
treatment, and we shall therefore examine the question by statistical
methods. [2] These have the further advantage of being more easily
understood; for facts which can be measured and expressed in numbers are
facts whose import the reader can usually decide for himself: he is
perfectly able to determine, without any special training, whether twice
two does or does not make four. One further preliminary remark: the
problem of nature vs. nurture can not be solved in general terms; a
moment's thought will show that it can be understood only by examining
one trait at a time. The problem is to decide whether the differences
between the people met in everyday life are due more to inheritance or
to outside influences, and these differences must naturally be examined
separately; they can not be lumped together.

To ask whether nature in general contributes more to a man than nurture
is futile; but it is not at all futile to ask whether the differences in
a given human trait are more affected by differences in nature than by
differences in nurture. It is easy to see that a verdict may be
sometimes given to one side, sometimes to the other. Albinism in
animals, for instance, is a trait which is known to be inherited, and
which is very slightly affected by differences of climate, food supply,
etc. On the other hand, there are factors which, although having
inherited bases, owe their expression almost wholly to outside
influences. Professor Morgan, for example, has found a strain of fruit
flies whose offspring in cold weather are usually born with
supernumerary legs. In hot weather they are practically normal. If this
strain were bred only in the tropics, the abnormality would probably not
be noticed; on the other hand, if it were bred only in cold regions, it
would be set down as one characterized by duplication of limbs. The
heredity factor would be the same in each case, the difference in
appearance being due merely to temperature.

Mere inspection does not always tell whether some feature of an
individual is more affected by changes in heredity or changes in
surroundings. On seeing a swarthy man, one may suppose that he comes of
a swarthy race, or that he is a fair-skinned man who has lived long in
the desert. In the one case the swarthiness would be inheritable, in the
other not. Which explanation is correct, can only be told by examining a
number of such individuals under critical conditions, or by an
examination of the ancestry. A man from a dark-skinned race would become
little darker by living under the desert sun, while a white man would
take on a good deal of tan.

The limited effect of nurture in changing nature is in some fields a
matter of common observation. The man who works in the gymnasium knows
that exercise increases the strength of a given group of muscles for a
while, but not indefinitely. There comes a time when the limit of a
man's hereditary potentiality is reached, and no amount of exercise will
add another millimeter to the circumference of his arm. Similarly the
handball or tennis player some day reaches his highest point, as do
runners or race horses. A trainer could bring Arthur Duffy in a few
years to the point of running a hundred yards in 9-3/5 seconds, but no
amount of training after that could clip off another fifth of a second.
A parallel case is found in the students who take a college examination.
Half a dozen of them may have devoted the same amount of time to it--may
have crammed to the limit--but they will still receive widely different
marks. These commonplace cases show that nurture has seemingly some
power to mold the individual, by giving his inborn possibilities a
chance to express themselves, but that nature says the first and last
word. Francis Galton, the father of eugenics, hit on an ingenious and
more convincing illustration by studying the history of twins. [3]

There are, everyday observation shows, two kinds of twins--ordinary
twins and the so-called identical twins. Ordinary twins are merely
brothers, or sisters, or brother and sister, who happen to be born two
at a time, because two ova have developed simultaneously. The fact that
they were born at the same time does not make them alike--they differ
quite as widely from each other as ordinary brothers and sisters do.
Identical twins have their origin in a different phenomenon--they are
believed to be halves of the same egg-cell, in which two growing-points
appeared at a very early embryonic stage, each of these developing into
a separate individual. As would be expected, these identical twins are
always of the same sex, and extremely like each other, so that sometimes
their own mother can not tell them apart. This likeness extends to all
sorts of traits:--they have lost their milk teeth on the same day in one
case, they even fell ill on the same day with the same disease, even
though they were in different cities.

Now Galton reasoned that if environment really changes the inborn
character, then these identical twins, who start life as halves of the
same whole, ought to become more unlike if they were brought up apart;
and as they grew older and moved into different spheres of activity,
they ought to become measurably dissimilar. On the other hand, ordinary
twins, who start dissimilar, ought to become more alike when brought up
in the same family, on the same diet, among the same friends, with the
same education. If the course of years shows that identical twins remain
as like as ever and ordinary twins as unlike as ever, regardless of
changes in conditions, then environment will have failed to demonstrate
that it has any great power to modify one's inborn nature in these
traits.

With this view, Galton collected the history of eighty pairs of
identical twins, thirty-five cases being accompanied by very full
details, which showed that the twins were really as nearly identical, in
childhood, as one could expect to find. On this point, Galton's
inquiries were careful, and the replies satisfactory. They are not,
however, as he remarks, much varied in character. "When the twins are
children, they are usually distinguished by ribbons tied around the
wrist or neck; nevertheless the one is sometimes fed, physicked, and
whipped by mistake for the other, and the description of these little
domestic catastrophes was usually given by the mother, in a phraseology,
that is sometimes touching by reason of its seriousness. I have one case
in which a doubt remains whether the children were not changed in their
bath, and the presumed A is not really B, and _vice versa_. In another
case, an artist was engaged on the portraits of twins who were between
three and four years of age; he had to lay aside his work for three
weeks, and, on resuming it, could not tell to which child the respective
likeness he had in hand belonged. The mistakes become less numerous on
the part of the mother during the boyhood and girlhood of the twins, but
are almost as frequent as before on the part of strangers. I have many
instances of tutors being unable to distinguish their twin pupils. Two
girls used regularly to impose on their music teacher when one of them
wanted a whole holiday; they had their lessons at separate hours, and
the one girl sacrificed herself to receive two lessons on the same day,
while the other one enjoyed herself from morning to evening. Here is a
brief and comprehensive account: 'Exactly alike in all, their
schoolmasters could never tell them apart; at dancing parties they
constantly changed partners without discovery; their close resemblance
is scarcely diminished by age. "

[Illustration: FOUR BABY GIRLS AT ONCE

FIG. 1. --These quadruplet daughters were born to Mr. and Mrs.
F. M. Keys, Hollis, Okla. , on July 4, 1915, and were seven months old
when the photograph was taken. Up to that time they had never had any
other nourishment than their mother's milk. Their weights at birth were
as follows (reading from left to right): Roberta, 4 pounds; Mona, 4-1/2
pounds; Mary, 4-1/4 pounds; Leota, 3-3/4 pounds.