We shall
therefore
examine
the first of them in this chapter, and the second in Chapter II.
the first of them in this chapter, and the second in Chapter II.
Applied Eugenics by Roswell H. Johnson and Paul Popenoe
The Project Gutenberg EBook of Applied Eugenics, by
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Title: Applied Eugenics
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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.
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. When photographed,
Roberta weighed 16 pounds and each of the others weighed 16-1/4. Their
aunt vouches for the fact that the care of the four is less trouble than
a single baby often makes. The mother has had no previous plural births,
although she has borne four children prior to these. Her own mother had
but two children, a son and a daughter, and there is no record of twins
on the mother's side. The father of the quadruplets is one of twelve
children, among whom is one pair of twins. It is known that twinning is
largely due to inheritance, and it would seem that the appearance of
these quadruplets is due to the hereditary influence of the father
rather than the mother. If this is the case, then the four girls must
all have come from one egg-cell, which split up at an early stage. Note
the uniform shape of the mouth, and the ears, set unusually low on the
head. ]
"The following is a typical schoolboy anecdote:
"'Two twins were fond of playing tricks, and complaints were frequently
made; but the boys would never own which was the guilty one, and the
complainants were never certain which of the two it was. One head master
used to say he would never flog the innocent for the guilty, and the
other used to flog them both. '
"No less than nine anecdotes have reached me of a twin seeing his or her
reflection in the looking-glass, and addressing it in the belief that it
was the other twin in person.
"Children are usually quick in distinguishing between their parent and
his or her twin; but I have two cases to the contrary. Thus, the
daughter of a twin says:
"'Such was the marvelous similarity of their features, voice, manner,
etc. , that I remember, as a child, being very much puzzled, and I think,
had my aunt lived much with us, I should have ended by thinking I had
two mothers! '
"In the other case, a father who was a twin, remarks of himself and his
brother:
"'We were extremely alike, and are so at this moment, so much so that
our children up to five and six years old did not know us apart. '
"Among my thirty-five detailed cases of close similarity, there are no
less than seven in which both twins suffered from some special ailment
or had some exceptional peculiarity. Both twins are apt to sicken at the
same time in no less than nine out of the thirty-five cases. Either
their illnesses, to which I refer, were non-contagious, or, if
contagious, the twins caught them simultaneously; they did not catch
them the one from the other. "
Similarity in association of ideas, in tastes and habits was equally
close. In short, their resemblances were not superficial, but extremely
intimate, both in mind and body, while they were young; they were reared
almost exactly alike up to their early manhood and womanhood.
Then they separated into different walks of life. Did this change of the
environment alter their inborn character? For the detailed evidence,
one should consult Galton's own account; we give only his conclusions:
In many cases the resemblance of body and mind continued unaltered up to
old age, notwithstanding very different conditions of life; in others a
severe disease was sufficient to account for some change noticed. Other
dissimilarity that developed, Galton had reason to believe, was due to
the development of inborn characters that appeared late in life. He
therefore felt justified in broadly concluding "that the only
circumstance, within the range of those by which persons of similar
conditions of life are affected, that is capable of producing a marked
effect on the character of adults, is illness or some accident which
causes physical infirmity. The twins who closely resembled each other in
childhood and early youth, and were reared under not very dissimilar
conditions, either grow unlike through the development of natural [that
is, inherited] characteristics which had lain dormant at first, or else
they continue their lives, keeping time like two watches, hardly to be
thrown out of accord except by some physical jar. "
Here was a distinct failure of nurture to modify the inborn nature. We
next consider the ordinary twins who were unlike from the start. Galton
had twenty such cases, given with much detail. "It is a fact," he
observes, "that extreme dissimilarity, such as existed between Jacob and
Esau, is a no less marked peculiarity of twins of the same sex than
extreme similarity. " The character of the evidence as a whole may be
fairly conveyed by a few quotations:
(1) One parent says: "They have had _exactly the same nurture_ from
their birth up to the present time; they are both perfectly healthy and
strong, yet they are otherwise as dissimilar as two boys could be,
physically, mentally, and in their emotional nature. "
(2) "I can answer most decidedly that the twins have been perfectly
dissimilar in character, habits, and likeness from the moment of their
birth to the present time, though they were nursed by the same woman,
went to school together, and were never separated until the age of
thirteen. "
(3) "They have never been separated, never the least differently treated
in food, clothing, or education; both teethed at the same time, both had
measles, whooping cough, and scarlatina at the same time, and neither
has had any other serious illness. Both are and have been exceedingly
healthy, and have good abilities; yet they differ as much from each
other in mental cast as any one of my family differs from another. "
(4) "Very dissimilar in mind and body; the one is quiet, retiring, and
slow but sure; good-tempered, but disposed to be sulky when
provoked;--the other is quick, vivacious, forward, acquiring easily and
forgetting soon; quick-tempered and choleric, but quickly forgiving and
forgetting. They have been educated together and never separated. "
(5) "They were never alike either in mind or body, and their
dissimilarity increases daily. The external influences have been
identical; they have never been separated. "
(6) "The two sisters are very different in ability and disposition. The
one is retiring, but firm and determined; she has no taste for music or
drawing. The other is of an active, excitable temperament; she displays
an unusual amount of quickness and talent, and is passionately fond of
music and drawing. From infancy, they have been rarely separated even at
school, and as children visiting their friends, they always went
together. "
And so on. Not a single case was found in which originally dissimilar
characters became assimilated, although submitted to exactly the same
influences. Reviewing the evidence in his usual cautious way, Galton
declared, "There is no escape from the conclusion that nature prevails
enormously over nurture, when the differences of nurture do not exceed
what is commonly to be found among persons of the same rank in society
and in the same country. "
This kind of evidence was a good start for eugenics but as the science
grew, it outgrew such evidence. It no longer wanted to be told, no
matter how minute the details, that "nature prevails enormously over
nurture. " It wanted to know exactly how much. It refused to be satisfied
with the statement that a certain quantity was large; it demanded that
it be measured or weighed. So Galton, Karl Pearson and other
mathematicians devised means of doing this, and then Professor Edward L.
Thorndike of Columbia University took up Galton's problem again, with
more refined methods.
The tool used by Professor Thorndike was the coefficient of correlation,
which shows the amount of resemblance or association between any two
things that are capable of measurement, and is expressed in the form of
a decimal fraction somewhere between 0 and the unit 1. Zero shows that
there is no constant resemblance at all between the two things
concerned,--that they are wholly independent of each other, while 1
shows that they are completely dependent on each other, a condition that
rarely exists, of course. [4] For instance, the correlation between the
right and left femur in man's legs is . 98.
Professor Thorndike found in the New York City schools fifty pairs of
twins of about the same age and measured the closeness of their
resemblance in eight physical characters, and also in six mental
characters, the latter being measured by the proficiency with which the
subjects performed various tests. Then children of the same age and sex,
picked at random from the same schools, were measured in the same way.
It was thus possible to tell how much more alike twins were than
ordinary children in the same environment. [5]
[Illustration: THE EFFECT OF NURTURE IN CHANGING NATURE
FIG. 2. --Corn of a single variety (Leaming Dent) grown in two
plots: at the left spaced far apart in hills, at the right crowded. The
former grows to its full potential height, the latter is stunted. The
size differences in the two plots are due to differences in environment,
the heredity in both cases being the same. Plants are much more
susceptible to nutritional influences on size than are mammals, but to a
less degree nutrition has a similar effect on man. Photograph from A. F.
Blakeslee. ]
"If now these resemblances are due to the fact that the two members of
any twin pair are treated alike at home, have the same parental models,
attend the same school and are subject in general to closely similar
environmental conditions, then (1) twins should, up to the age of
leaving home, grow more and more alike, and in our measurements the
twins 13 and 14 years old should be much more alike than those 9 and 10
years old. Again (2) if similarity in training is the cause of
similarity in mental traits, ordinary fraternal pairs not over four or
five years apart in age should show a resemblance somewhat nearly as
great as twin pairs, for the home and school condition of a pair of the
former will not be much less similar than those of a pair of the latter.
Again, (3) if training is the cause, twins should show greater
resemblance in the case of traits much subject to training, such as
ability in addition or multiplication, than in traits less subject to
training, such as quickness in marking off the A's on a sheet of printed
capitals, or in writing the opposites of words. "
The data were elaborately analyzed from many points of view. They showed
(1) that the twins 12-14 years old were not any more alike than the
twins 9-11 years old, although they ought to have been, if environment
has great power to mold the character during these so-called "plastic
years of childhood. " They showed (2) that the resemblance between twins
was two or three times as great as between ordinary children of the same
age and sex, brought up under similar environment. There seems to be no
reason, except heredity, why twins should be more alike. The data showed
(3) that the twins were no more alike in traits subject to much training
than in traits subject to little or no training. Their achievement in
these traits was determined by their heredity; training did not
measurably alter these hereditary potentialities.
"The facts," Professor Thorndike wrote, "are easily, simply and
completely explained by one simple hypothesis; namely, that the nature
of the germ-cells--the conditions of conception--cause whatever
similarities and differences exist in the original natures of men, that
these conditions influence mind and body equally, and that in life the
differences in modification of mind and body produced by such
differences as obtain between the environments of present-day New York
City public school children are slight. "
"The inferences," he says, "with respect to the enormous importance of
original nature in determining the behavior and achievements of any man
in comparison with his fellows of the same period of civilization and
conditions of life are obvious. All theories of human life must accept
as a first principle the fact that human beings at birth differ
enormously in mental capacities and that these differences are largely
due to similar differences in their ancestry. All attempts to change
human nature must accept as their most important condition the limits
set by original nature to each individual. "
Meantime other investigators, principally followers of Karl Pearson in
England, were working out correlation coefficients in other lines of
research for hundreds of different traits. As we show in more detail in
Chapter IV, it was found, no matter what physical or mental trait was
measured, that the coefficient of correlation between parent and child
was a little less than . 5 and that the coefficient between brother and
brother, or sister and sister, or brother and sister, was a little more
than . 5. On the average of many cases the mean "nature" value, the
coefficient of direct heredity, was placed at . 51. This gave another
means of measuring nurture, for it was also possible to measure the
relation between any trait in the child and some factor in the
environment. A specific instance will make this clearer.
Groups of school children usually show an appalling percentage of
short-sightedness. Now suppose it is suggested that this is because they
are allowed to learn to read at too early an age. One can find out the
age at which any given child did learn to read, and work out the
coefficient of correlation between this age and the child's amount of
myopia. If the relation between them is very close--say . 7 or . 8--it
will be evident that the earlier a child learns to read, the more
short-sighted he is as he grows older. This will not prove a relation of
cause and effect, but it will at least create a great suspicion. If on
the contrary the correlation is very slight, it will be evident that
early reading has little to do with the prevalance of defective vision
among school children. If investigators similarly work out all the other
correlations that can be suggested, finding whether there is any
regular relation between myopia and overcrowding, long hours of study,
general economic conditions at home, general physical or moral
conditions of parents, the time the child spends out of doors, etc. , and
if no important relation is found between these various factors and
myopia, it will be evident that no factor of the environment which one
can think of as likely to cause the trouble really accounts for the poor
eyesight of school children.
[Illustration: HEIGHT IN CORN AND MEN
FIG. 3. --An unusually short and an unusually tall man,
photographed beside extreme varieties of corn which, like the men, owe
their differences in height indisputably to heredity rather than to
environment. No imaginable environmental differences could reverse the
positions of these two men, or of these two varieties of corn, the
heredity in each case being what it is. The large one might be stunted,
but the small one could not be made much larger. Photograph from A. F.
Blakeslee. ]
This has actually been done,[6] and none of the conditions enumerated
has been found to be closely related to myopia in school children.
Correlations between fifteen environmental conditions and the goodness
of children's eyesight were measured, and only in one case was the
correlation as high as . 1. The mean of these correlations was about
. 04--an absolutely negligible quantity when compared with the common
heredity coefficient of . 51.
Does this prove that the myopia is rather due to heredity? It would, by
a process of exclusion, if every conceivable environmental factor had
been measured and found wanting. That point in the investigation can
never be reached, but a tremendously strong suspicion is at least
justified. Now if the degree of resemblance between the prevalence of
myopia in parents and that in children be directly measured, and if it
be found that when the parent has eye trouble the child also has it,
then it seems that a general knowledge of heredity should lead to the
belief that the difficulty lies there, and that an environmental cause
for the poor vision of the school child was being sought, when it was
all the time due almost entirely to heredity. This final step has not
yet been completed in an adequate way,[7] but the evidence, partly
analogical, gives every reason to believe in the soundness of the
conclusion stated, that in most cases the schoolboy must wear glasses
because of his heredity, not because of overstudy or any neglect on the
part of his parents to care for his eyes properly during his childhood.
[Illustration: WHY MEN GROW SHORT OR TALL
FIG. 4. --Pedigree charts of the two men shown in the preceding
illustration. Squares represent men and circles women; figures
underlined denote measurement in stocking feet. It is obvious from a
comparison of the ancestry of the two men that the short one comes from
a predominantly short family, while the tall one gains his height
likewise from heredity. The shortest individual in the right-hand chart
would have been accounted tall in the family represented on the left.
After A. F. Blakeslee. ]
The extent to which the intelligence of school children is dependent on
defective physique and unfavorable home environment is an important
practical question, which David Heron of London attacked by the methods
we have outlined. He wanted to find out whether the healthy children
were the most intelligent. One is constantly hearing stories of how the
intelligence of school children has been improved by some treatment
which improved their general health, but these stories are rarely
presented in such a way as to contribute evidence of scientific value.
It was desirable to know what exact measurement would show.
Paul Popenoe and Roswell Hill Johnson
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Title: Applied Eugenics
Author: Paul Popenoe and Roswell Hill Johnson
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Language: English
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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.
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. When photographed,
Roberta weighed 16 pounds and each of the others weighed 16-1/4. Their
aunt vouches for the fact that the care of the four is less trouble than
a single baby often makes. The mother has had no previous plural births,
although she has borne four children prior to these. Her own mother had
but two children, a son and a daughter, and there is no record of twins
on the mother's side. The father of the quadruplets is one of twelve
children, among whom is one pair of twins. It is known that twinning is
largely due to inheritance, and it would seem that the appearance of
these quadruplets is due to the hereditary influence of the father
rather than the mother. If this is the case, then the four girls must
all have come from one egg-cell, which split up at an early stage. Note
the uniform shape of the mouth, and the ears, set unusually low on the
head. ]
"The following is a typical schoolboy anecdote:
"'Two twins were fond of playing tricks, and complaints were frequently
made; but the boys would never own which was the guilty one, and the
complainants were never certain which of the two it was. One head master
used to say he would never flog the innocent for the guilty, and the
other used to flog them both. '
"No less than nine anecdotes have reached me of a twin seeing his or her
reflection in the looking-glass, and addressing it in the belief that it
was the other twin in person.
"Children are usually quick in distinguishing between their parent and
his or her twin; but I have two cases to the contrary. Thus, the
daughter of a twin says:
"'Such was the marvelous similarity of their features, voice, manner,
etc. , that I remember, as a child, being very much puzzled, and I think,
had my aunt lived much with us, I should have ended by thinking I had
two mothers! '
"In the other case, a father who was a twin, remarks of himself and his
brother:
"'We were extremely alike, and are so at this moment, so much so that
our children up to five and six years old did not know us apart. '
"Among my thirty-five detailed cases of close similarity, there are no
less than seven in which both twins suffered from some special ailment
or had some exceptional peculiarity. Both twins are apt to sicken at the
same time in no less than nine out of the thirty-five cases. Either
their illnesses, to which I refer, were non-contagious, or, if
contagious, the twins caught them simultaneously; they did not catch
them the one from the other. "
Similarity in association of ideas, in tastes and habits was equally
close. In short, their resemblances were not superficial, but extremely
intimate, both in mind and body, while they were young; they were reared
almost exactly alike up to their early manhood and womanhood.
Then they separated into different walks of life. Did this change of the
environment alter their inborn character? For the detailed evidence,
one should consult Galton's own account; we give only his conclusions:
In many cases the resemblance of body and mind continued unaltered up to
old age, notwithstanding very different conditions of life; in others a
severe disease was sufficient to account for some change noticed. Other
dissimilarity that developed, Galton had reason to believe, was due to
the development of inborn characters that appeared late in life. He
therefore felt justified in broadly concluding "that the only
circumstance, within the range of those by which persons of similar
conditions of life are affected, that is capable of producing a marked
effect on the character of adults, is illness or some accident which
causes physical infirmity. The twins who closely resembled each other in
childhood and early youth, and were reared under not very dissimilar
conditions, either grow unlike through the development of natural [that
is, inherited] characteristics which had lain dormant at first, or else
they continue their lives, keeping time like two watches, hardly to be
thrown out of accord except by some physical jar. "
Here was a distinct failure of nurture to modify the inborn nature. We
next consider the ordinary twins who were unlike from the start. Galton
had twenty such cases, given with much detail. "It is a fact," he
observes, "that extreme dissimilarity, such as existed between Jacob and
Esau, is a no less marked peculiarity of twins of the same sex than
extreme similarity. " The character of the evidence as a whole may be
fairly conveyed by a few quotations:
(1) One parent says: "They have had _exactly the same nurture_ from
their birth up to the present time; they are both perfectly healthy and
strong, yet they are otherwise as dissimilar as two boys could be,
physically, mentally, and in their emotional nature. "
(2) "I can answer most decidedly that the twins have been perfectly
dissimilar in character, habits, and likeness from the moment of their
birth to the present time, though they were nursed by the same woman,
went to school together, and were never separated until the age of
thirteen. "
(3) "They have never been separated, never the least differently treated
in food, clothing, or education; both teethed at the same time, both had
measles, whooping cough, and scarlatina at the same time, and neither
has had any other serious illness. Both are and have been exceedingly
healthy, and have good abilities; yet they differ as much from each
other in mental cast as any one of my family differs from another. "
(4) "Very dissimilar in mind and body; the one is quiet, retiring, and
slow but sure; good-tempered, but disposed to be sulky when
provoked;--the other is quick, vivacious, forward, acquiring easily and
forgetting soon; quick-tempered and choleric, but quickly forgiving and
forgetting. They have been educated together and never separated. "
(5) "They were never alike either in mind or body, and their
dissimilarity increases daily. The external influences have been
identical; they have never been separated. "
(6) "The two sisters are very different in ability and disposition. The
one is retiring, but firm and determined; she has no taste for music or
drawing. The other is of an active, excitable temperament; she displays
an unusual amount of quickness and talent, and is passionately fond of
music and drawing. From infancy, they have been rarely separated even at
school, and as children visiting their friends, they always went
together. "
And so on. Not a single case was found in which originally dissimilar
characters became assimilated, although submitted to exactly the same
influences. Reviewing the evidence in his usual cautious way, Galton
declared, "There is no escape from the conclusion that nature prevails
enormously over nurture, when the differences of nurture do not exceed
what is commonly to be found among persons of the same rank in society
and in the same country. "
This kind of evidence was a good start for eugenics but as the science
grew, it outgrew such evidence. It no longer wanted to be told, no
matter how minute the details, that "nature prevails enormously over
nurture. " It wanted to know exactly how much. It refused to be satisfied
with the statement that a certain quantity was large; it demanded that
it be measured or weighed. So Galton, Karl Pearson and other
mathematicians devised means of doing this, and then Professor Edward L.
Thorndike of Columbia University took up Galton's problem again, with
more refined methods.
The tool used by Professor Thorndike was the coefficient of correlation,
which shows the amount of resemblance or association between any two
things that are capable of measurement, and is expressed in the form of
a decimal fraction somewhere between 0 and the unit 1. Zero shows that
there is no constant resemblance at all between the two things
concerned,--that they are wholly independent of each other, while 1
shows that they are completely dependent on each other, a condition that
rarely exists, of course. [4] For instance, the correlation between the
right and left femur in man's legs is . 98.
Professor Thorndike found in the New York City schools fifty pairs of
twins of about the same age and measured the closeness of their
resemblance in eight physical characters, and also in six mental
characters, the latter being measured by the proficiency with which the
subjects performed various tests. Then children of the same age and sex,
picked at random from the same schools, were measured in the same way.
It was thus possible to tell how much more alike twins were than
ordinary children in the same environment. [5]
[Illustration: THE EFFECT OF NURTURE IN CHANGING NATURE
FIG. 2. --Corn of a single variety (Leaming Dent) grown in two
plots: at the left spaced far apart in hills, at the right crowded. The
former grows to its full potential height, the latter is stunted. The
size differences in the two plots are due to differences in environment,
the heredity in both cases being the same. Plants are much more
susceptible to nutritional influences on size than are mammals, but to a
less degree nutrition has a similar effect on man. Photograph from A. F.
Blakeslee. ]
"If now these resemblances are due to the fact that the two members of
any twin pair are treated alike at home, have the same parental models,
attend the same school and are subject in general to closely similar
environmental conditions, then (1) twins should, up to the age of
leaving home, grow more and more alike, and in our measurements the
twins 13 and 14 years old should be much more alike than those 9 and 10
years old. Again (2) if similarity in training is the cause of
similarity in mental traits, ordinary fraternal pairs not over four or
five years apart in age should show a resemblance somewhat nearly as
great as twin pairs, for the home and school condition of a pair of the
former will not be much less similar than those of a pair of the latter.
Again, (3) if training is the cause, twins should show greater
resemblance in the case of traits much subject to training, such as
ability in addition or multiplication, than in traits less subject to
training, such as quickness in marking off the A's on a sheet of printed
capitals, or in writing the opposites of words. "
The data were elaborately analyzed from many points of view. They showed
(1) that the twins 12-14 years old were not any more alike than the
twins 9-11 years old, although they ought to have been, if environment
has great power to mold the character during these so-called "plastic
years of childhood. " They showed (2) that the resemblance between twins
was two or three times as great as between ordinary children of the same
age and sex, brought up under similar environment. There seems to be no
reason, except heredity, why twins should be more alike. The data showed
(3) that the twins were no more alike in traits subject to much training
than in traits subject to little or no training. Their achievement in
these traits was determined by their heredity; training did not
measurably alter these hereditary potentialities.
"The facts," Professor Thorndike wrote, "are easily, simply and
completely explained by one simple hypothesis; namely, that the nature
of the germ-cells--the conditions of conception--cause whatever
similarities and differences exist in the original natures of men, that
these conditions influence mind and body equally, and that in life the
differences in modification of mind and body produced by such
differences as obtain between the environments of present-day New York
City public school children are slight. "
"The inferences," he says, "with respect to the enormous importance of
original nature in determining the behavior and achievements of any man
in comparison with his fellows of the same period of civilization and
conditions of life are obvious. All theories of human life must accept
as a first principle the fact that human beings at birth differ
enormously in mental capacities and that these differences are largely
due to similar differences in their ancestry. All attempts to change
human nature must accept as their most important condition the limits
set by original nature to each individual. "
Meantime other investigators, principally followers of Karl Pearson in
England, were working out correlation coefficients in other lines of
research for hundreds of different traits. As we show in more detail in
Chapter IV, it was found, no matter what physical or mental trait was
measured, that the coefficient of correlation between parent and child
was a little less than . 5 and that the coefficient between brother and
brother, or sister and sister, or brother and sister, was a little more
than . 5. On the average of many cases the mean "nature" value, the
coefficient of direct heredity, was placed at . 51. This gave another
means of measuring nurture, for it was also possible to measure the
relation between any trait in the child and some factor in the
environment. A specific instance will make this clearer.
Groups of school children usually show an appalling percentage of
short-sightedness. Now suppose it is suggested that this is because they
are allowed to learn to read at too early an age. One can find out the
age at which any given child did learn to read, and work out the
coefficient of correlation between this age and the child's amount of
myopia. If the relation between them is very close--say . 7 or . 8--it
will be evident that the earlier a child learns to read, the more
short-sighted he is as he grows older. This will not prove a relation of
cause and effect, but it will at least create a great suspicion. If on
the contrary the correlation is very slight, it will be evident that
early reading has little to do with the prevalance of defective vision
among school children. If investigators similarly work out all the other
correlations that can be suggested, finding whether there is any
regular relation between myopia and overcrowding, long hours of study,
general economic conditions at home, general physical or moral
conditions of parents, the time the child spends out of doors, etc. , and
if no important relation is found between these various factors and
myopia, it will be evident that no factor of the environment which one
can think of as likely to cause the trouble really accounts for the poor
eyesight of school children.
[Illustration: HEIGHT IN CORN AND MEN
FIG. 3. --An unusually short and an unusually tall man,
photographed beside extreme varieties of corn which, like the men, owe
their differences in height indisputably to heredity rather than to
environment. No imaginable environmental differences could reverse the
positions of these two men, or of these two varieties of corn, the
heredity in each case being what it is. The large one might be stunted,
but the small one could not be made much larger. Photograph from A. F.
Blakeslee. ]
This has actually been done,[6] and none of the conditions enumerated
has been found to be closely related to myopia in school children.
Correlations between fifteen environmental conditions and the goodness
of children's eyesight were measured, and only in one case was the
correlation as high as . 1. The mean of these correlations was about
. 04--an absolutely negligible quantity when compared with the common
heredity coefficient of . 51.
Does this prove that the myopia is rather due to heredity? It would, by
a process of exclusion, if every conceivable environmental factor had
been measured and found wanting. That point in the investigation can
never be reached, but a tremendously strong suspicion is at least
justified. Now if the degree of resemblance between the prevalence of
myopia in parents and that in children be directly measured, and if it
be found that when the parent has eye trouble the child also has it,
then it seems that a general knowledge of heredity should lead to the
belief that the difficulty lies there, and that an environmental cause
for the poor vision of the school child was being sought, when it was
all the time due almost entirely to heredity. This final step has not
yet been completed in an adequate way,[7] but the evidence, partly
analogical, gives every reason to believe in the soundness of the
conclusion stated, that in most cases the schoolboy must wear glasses
because of his heredity, not because of overstudy or any neglect on the
part of his parents to care for his eyes properly during his childhood.
[Illustration: WHY MEN GROW SHORT OR TALL
FIG. 4. --Pedigree charts of the two men shown in the preceding
illustration. Squares represent men and circles women; figures
underlined denote measurement in stocking feet. It is obvious from a
comparison of the ancestry of the two men that the short one comes from
a predominantly short family, while the tall one gains his height
likewise from heredity. The shortest individual in the right-hand chart
would have been accounted tall in the family represented on the left.
After A. F. Blakeslee. ]
The extent to which the intelligence of school children is dependent on
defective physique and unfavorable home environment is an important
practical question, which David Heron of London attacked by the methods
we have outlined. He wanted to find out whether the healthy children
were the most intelligent. One is constantly hearing stories of how the
intelligence of school children has been improved by some treatment
which improved their general health, but these stories are rarely
presented in such a way as to contribute evidence of scientific value.
It was desirable to know what exact measurement would show.
