"
The right understanding of this famous problem is therefore fraught with
the most important consequences to eugenics.
The right understanding of this famous problem is therefore fraught with
the most important consequences to eugenics.
Applied Eugenics by Roswell H. Johnson and Paul Popenoe
But
in general there have been wars going on during the whole period of
modern European history; there have always been opportunities for a
royal hero to make his appearance; but often the country has called for
many years in vain. Circumstances were powerless to produce a great man
and the nation had to wait until heredity produced him. Spain has for
several centuries been calling for genius in leadership in some lines;
but in vain. England could not get an able man from the Stuart line,
despite her need, and had to wait for William of Orange, who was a
descendant of a man of genius, William the Silent. "Italy had to wait
fifty years in bondage for her deliverers, Cavour, Garibaldi and Victor
Emmanuel. "
"The upshot of it all," Dr. Woods decides, "is that, as regards
intellectual life, environment is a totally inadequate explanation. If
it explains certain characters in certain instances, it always fails to
explain many more, while heredity not only explains all, or at least
90%, of the intellectual side of character in practically every
instance, but does so best when questions of environment are left out of
discussion. "
Despite the good environment almost uniformly present, the geniuses in
royalty are not scattered over the surface of the pedigree chart, but
form isolated little groups of closely related individuals. One centers
in Frederick the Great, another in Queen Isabella of Spain, a third in
William the Silent, and a fourth in Gustavus Adolphus. Furthermore, the
royal personages who are conspicuously low in intellect and morality are
similarly grouped. Careful study of the circumstances shows nothing in
the environment that would produce this grouping of genius, while it is
exactly what a knowledge of heredity leads one to expect.
In the next place, do the superior members of royalty have
proportionately more superior individuals among their close relatives,
as was found to be the case among the Americans in the Hall of Fame? A
count shows at once that they do. The first six grades all have about an
equal number of eminent relatives, but grade 7 has more while grade 8
has more than grade 7, and the geniuses of grade 10 have the highest
proportion of nearer relatives of their own character. Surely it cannot
be supposed that a relative of a king in grade 8 has on the average a
much less favorable environment than a relative of a king in grade 10.
Is it not fair, then, to assume that this relative's greater endowment
in the latter case is due to heredity?
Conditions are the same, whether males or females be considered. The
royal families of Europe offer a test case because for them the
environment is nearly uniformly favorable. A study of them shows great
mental and moral differences between them, and critical evidence
indicates that these differences are largely due to differences in
heredity. Differences of opportunity do not appear to be largely
responsible for the achievements of the individuals.
But, it is sometimes objected, opportunity certainly is responsible for
the appearance of much talent that would otherwise never appear. Take
the great increase in the number of scientific men in Germany during the
last half century, for example. It can not be pretended that this is due
to an increased birth-rate of such talent; it means that the growth of
an appreciation of scientific work has produced an increased amount of
scientific talent. J. McKeen Cattell has argued this point most
carefully in his study of the families of one thousand American men of
science (_Popular Science Monthly_, May, 1915). "A Darwin born in China
in 1809," he says, "could not have become a Darwin, nor could a Lincoln
born here on the same day have become a Lincoln had there been no Civil
War. If the two infants had been exchanged there would have been no
Darwin in America and no Lincoln in England. " And so he continues,
urging that in the production of scientific men, at least, education is
more important than eugenics.
This line of argument contains a great deal of obvious truth, but is
subject to a somewhat obvious objection, if it is pushed too far. It is
certainly true that the exact field in which a man's activities will
find play is largely determined by his surroundings and education. Young
men in the United States are now becoming lawyers or men of science, who
would have become ministers had they been born a century or two ago. But
this environmental influence seems to us a minor one, for the man who is
highly gifted in some one line is usually, as all the work of
differential psychology shows, gifted more than the average in many
other lines. Opportunity decides in just what field his life work shall
lie; but he would be able to make a success in a number of fields.
Darwin born in America would probably not have become the Darwin we
know, but it is not to be supposed that he would have died a "mute,
inglorious Milton": it is not likely that he would have failed to make
his mark in some line of human activity. Dr. Cattell's argument, then,
while admissible, can not properly be urged against the fact that
ability is mainly dependent on inheritance.
We need not stop with the conclusion that equality of training or
opportunity is unable to level the inborn differences between men. We
can go even farther, and produce evidence to show that equality of
training _increases the differences_ in results achieved.
This evidence is obtained by measuring the effects of equal amounts of
exercise of a function upon individual differences in respect to
efficiency in it. Suppose one should pick out, at random, eight
children, and let them do problems in multiplication for 10 minutes.
After a number of such trials, the three best might average 39 correct
solutions in the 10 minutes, and the three poorest might average 25
examples. Then let them continue the work, until each one of them has
done 700 examples. Here is equality in training; does it lead to uniform
results?
Dr. Starch made the actual test which we have outlined and found that
the three best pupils gained on the average 45 in the course of doing
700 examples; while the three poorest gained only 26 in the same course
of time.
Similar tests have been made of school children in a number of
instances, and have shown that equality of training fails to bring about
equality of performance. All improve to some extent; but those who are
naturally better than their comrades usually become better still, when
conditions for all are the same. E. L. Thorndike gives[12] the following
tabular statement of a test he conducted:
THE EFFECT OF EQUAL AMOUNTS OF PRACTICE UPON INDIVIDUAL DIFFERENCES
IN THE MENTAL MULTIPLICATION OF A THREE-PLACE BY A THREE-PLACE
NUMBER
Amount done Percentage of
per unit of correct figures
time in answers
Hours of Practice
|
| First 5 Examples First 5 Examples
| | |
| | Last 5 or 10 | Last 5 or 10
| | Examples | Examples
| | | | |
| | | Gain | | Gain
Initial highest five individuals 5. 1 85 147 61 70 78 18
" next five " 5. 1 56 107 51 68 78 10
" " six " 5. 3 46 68 22 74 82 8
" " six " 5. 4 38 46 8 58 70 12
" " five " 5. 2 31 57 26 47 67 20
" " one individual 5. 2 19 32 13 100 82 -18
Similar results have been obtained by half a dozen other experimenters,
using the tests of mental multiplication, addition, marking A's on a
printed sheet of capitals, and the like. It would be a mistake to
conclude too much from experiments of such restricted scope; but they
all agree in showing that if every child were given an equal training,
the differences in these traits would nevertheless be very great.
And although we do not wish to strain the application of these results
too far, we are at least justified in saying that they strongly indicate
that inborn mediocrity can not be made into a high grade of talent by
training. Not every boy has a chance to distinguish himself, even if he
receives a good education.
We are driven back to the same old conclusion, that it is primarily
inborn nature which causes the achievements of men and women to be what
they are. Good environment, opportunity, training, will give good
heredity a chance to express itself; but they can not produce greatness
from bad heredity.
These conclusions are familiar to scientific sociologists, but they have
not yet had the influence on social service and practical attempts at
reform which they deserve. Many popular writers continue to confuse
cause and effect, as for example H. Addington Bruce, who contributed an
article to the _Century Magazine_, not long ago, on "The Boy Who Goes
Wrong. " After alleging that the boy who goes wrong does so because he is
not properly brought up, Mr. Bruce quotes with approval the following
passage from Paul Dubois, "the eminent Swiss physician and philosopher:
"If you have the happiness to be a well-living man, take care not to
attribute the credit of it to yourself. Remember the favorable
conditions in which you have lived, surrounded by the relatives who
loved you and set you a good example; do not forget the close friends
who have taken you by the hand and led you away from the quagmires of
evil; keep a grateful remembrance for all the teachers who have
influenced you, the kind and intelligent school-master, the devoted
pastor; realize all these multiple influences which have made you what
you are. Then you will remember that such and such a culprit has not in
his sad life met with these favorable conditions; that he had a drunken
father or a foolish mother, and that he has lived without affection,
exposed to all kinds of temptation. You will then take pity upon this
disinherited man, whose mind has been nourished upon malformed mental
images, begetting evil sentiments such as immoderate desire or social
hatred. "
Mr. Bruce indorses this kind of talk when he concludes, "The blame for
the boy who goes wrong does not rest with the boy himself, or yet with
his remote ancestors. It rests squarely with the parents who, through
ignorance or neglect, have failed to mold him aright in the plastic days
of childhood. "
Where is the evidence of the existence of these plastic days of
childhood? If they exist, why do not ordinary brothers become as much
alike as identical twins? How long are we to be asked to believe, on
blind faith, that the child is putty, of which the educator can make
either mediocrity or genius, depending on his skill? What does the
environmentalist _know_ about these "plastic days"? If a boy has a
drunken father or foolish mother, does it not suggest that there is
something wrong with his pedigree? With such an ancestry, we do not
expect him to turn out brilliantly, no matter in what home he is brought
up. If a boy has the kind of parents who bring him up well; if he is,
as Dr. Dubois says, surrounded by relatives who love him and set him a
good example, we at once have ground for a suspicion that he comes of a
pretty good family, a stock characterized by a high standard of
intellectuality and morality, and it would surprise us if such a boy did
not turn out well. But he turns out well because what's bred in the bone
will show in him, if it gets any kind of a chance. It is his nature, not
his nurture, that is mainly responsible for his character.
CHAPTER II
MODIFICATION OF THE GERM-PLASM
Every living creature was at some stage of its life nothing more than a
single cell. It is generally known that human beings result from the
union of an egg-cell and a sperm-cell, but it is not so universally
understood that these germ-cells are part of a continuous stream of
germ-plasm which has been in existence ever since the appearance of life
on the globe, and which is destined to continue in existence as long as
life remains on the globe.
The corollaries of this fact are of great importance. Some of them will
be considered in this chapter.
Early investigators tended naturally to look on the germ-cells as a
product of the body. Being supposedly products of the body, it was
natural to think that they would in some measure reproduce the character
of the body which created them; and Darwin elaborated an ingenious
hypothesis to explain how the various characters could be represented in
the germ-cell. The idea held by him, in common with most other thinkers
of his period, is still held more or less unconsciously by those who
have not given particular attention to the subject. Generation is
conceived as a direct chain: the body produces the germ-cell which
produces another body which in turn produces another germ-cell, and so
on.
But a generation ago this idea fell under suspicion. August Weismann,
professor of zoology in the University of Freiburg, Germany, made
himself the champion of the new idea, about 1885, and developed it so
effectively that it is now a part of the creed of nearly every
biologist.
Weismann caused a general abandonment of the idea that the germ-cell is
produced by the body in each generation, and popularized the conception
of the germ-cell as a product of a stream of undifferentiated
germ-plasm, not only continuous but (potentially at least) immortal.
The body does not produce the germ-cells, he pointed out; instead, the
germ-cells produce the body.
The basis of this theory can best be understood by a brief consideration
of the reproduction of very simple organisms.
"Death is the end of life," is the belief of many other persons than the
Lotus Eaters. It is commonly supposed that everything which lives must
eventually die. But study of a one-celled animal, an Infusorian, for
example, reveals that when it reaches a certain age it pinches in two,
and each half becomes an Infusorian in all appearance identical with the
original cell. Has the parent cell then died? It may rather be said to
survive, in two parts. Each of these daughter cells will in turn go
through the same process of reproduction by simple fission, and the
process will be continued in their descendants. The Infusorian can be
called potentially immortal, because of this method of reproduction.
The immortality, as Weismann pointed out, is not of the kind attributed
by the Greeks to their gods, who could not die because no wound could
destroy them. On the contrary, the Infusorian is extremely fragile, and
is dying by millions at every instant; but if circumstances are
favorable, it _can_ live on; it is not inevitably doomed to die sooner
or later, as is Man. "It dies from accident often, from old age never. "
Now the single-celled Infusorian is in many respects comparable with the
single-celled germ of the higher animals. The analogy has often been
carried too far; yet it remains indisputable that the germ-cells of men
reproduce in the same way--by simple fission--as the Infusorian and
other one-celled animals and plants, and that they are organized on much
the same plan. Given favorable circumstances, the germ-cell should be
expected to be equally immortal. Does it ever find these favorable
circumstances?
The investigations of microscopists indicate that it does--that
evolution has provided it with these favorable circumstances, in the
bodies of the higher animals. Let us recall in outline the early history
of the fertilized germ-cell, the _zygote_ formed by the union of ovum
and spermatozoon. These two unite to form a single cell, which is
essentially the same, physiologically, as other germ-cells. It divides
in two similar cells; these each divide; the resulting cells again
divide, and so the process continues, until the whole body--a fully
developed man,--has been produced by division and redivision of the one
zygote.
But the germ-cell is obviously different from most of the cells that
make up the finished product, the body. The latter are highly
differentiated and specialized for different functions--blood cells,
nerve cells, bone cells, muscle cells, and so on, each a single cell but
each adapted to do a certain work, for which the original,
undifferentiated germ-cell was wholly unfit. It is evident that
differentiation began to take place at some point in the series of
divisions, that is to say, in the development of the embryo.
Th. Boveri, studying the development of a threadworm, made the
interesting discovery that this differentiation began at the first
division. Of the two daughter-cells produced from the zygote, one
continued dividing at a very slow rate, and without showing any
specialization. Its "line of descent" produced only germ-cells. The
products of division of the other daughter-cell began to differentiate,
and soon formed all the necessary kinds of cells to make up the body of
the mature worm. In this body, the cells from the first daughter-cell
mentioned were inclosed, still undifferentiated: they formed the
germ-cells of the next generation, and after maturity were ready to be
ejected from the body, and to form new threadworms.
Imagine this process taking place through generation after generation of
threadworms, and one will realize that the germ-plasm was passed on
directly from one generation to the next; that in each generation it
gave rise to body-plasm, but that it did not at any time lose its
identity or continuity, a part of the germ-plasm being always set aside,
undifferentiated, to be handed on to the next generation.
In the light of this example, one can better understand the definition
of germ-plasm as "that part of the substance of the parents which does
not die with them, but perpetuates itself in their offspring. " By
bringing his imagination into play, the reader will realize that there
is no limit to the backward continuity of this germ-plasm in the
threadworm. Granted that each species has arisen by evolution from some
other, this germ-cell which is observed in the body of the threadworm,
must be regarded as part of what may well be called a stream of
germ-plasm, that reaches back to the beginning of life in the world. It
will be equally evident that these is no foreordained limit to the
forward extension of the stream. It will continue in some branch, as
long as there are any threadworms or descendants of threadworms in the
world.
The reader may well express doubt as to whether what has been
demonstrated for the threadworm can be demonstrated for the higher
animals, including man. It must be admitted that in many of these
animals conditions are too unfavorable, and the process of embryology
too complicated, or too difficult to observe, to permit as distinct a
demonstration of this continuity of the germ-plasm, wherever it is
sought. But it has been demonstrated in a great many animals; no facts
which impair the theory have been discovered; and biologists therefore
feel perfectly justified in generalizing and declaring the continuity of
germ-plasm to be a law of the world of living things.
Focusing attention on its application to man, one sees that the race
must represent an immense network of lines of descent, running back
through a vast number of different forms of gradually diminishing
specialization, until it comes to a point where all its threads merge in
one knot--the single cell with which it may be supposed that life on
this globe began. Each individual is not only figuratively, but in a
very literal sense, the carrier of the heritage of the whole race--of
the whole past, indeed. Each individual is temporarily the custodian of
part of the "stuff of life"; from an evolutionary point of view, he may
be said to have been brought into existence, primarily to pass this
sacred heritage on to the next generation. From Nature's standpoint, he
is of little use in the world, his existence is scarcely justified,
unless he faithfully discharges this trust, passing on to the future
the "Lamp of Life" whose fire he has been created to guard for a short
while.
Immortality, we may point out in passing, is thus no mere _hope_ to the
parent: it is a _real possibility_. The death of the huge agglomeration
of highly specialized body-cells is a matter of little consequence, if
the germ-plasm, with its power to reproduce not only these body-cells,
but the mental traits--indeed, we may in a sense say the very soul--that
inhabited them, has been passed on. The individual continues to live, in
his offspring, just as the past lives in him. To the eugenist, life
everlasting is something more than a figure of speech or a theological
concept--it is as much a reality as the beat of the heart, the growth of
muscles or the activity of the mind.
This doctrine of the continuity of germ-plasm throws a fresh light on
the nature of human relationships. It is evident that the son who
resembles his father can not accurately be called a "chip off the old
block. " Rather, they are both chips off the same block; and aside from
bringing about the fusion of two distinct strains of germ-plasm, father
and mother are no more responsible for endowing the child with its
characters except in the choice of mate, than is the child for "stamping
his impress" on his parents. From another point of view, it has been
said that father and son ought to be thought of as half-brothers by two
different mothers, each being the product of the same strain of paternal
germ-plasm, but not of the same strain of maternal germ-plasm.
Biologically, the father or mother should not be thought of as the
_producer_ of a child, but as the trustee of a stream of germ-plasm
which produces a child whenever the proper conditions arise. Or as Sir
Michael Foster put it, "The animal body is in reality a vehicle for ova
or sperm; and after the life of the parent has become potentially
renewed in the offspring, the body remains as a cast-off envelope whose
future is but to die. " Finally to quote the metaphor of J. Arthur
Thomson, one may "think for a moment of a baker who has a very precious
kind of leaven; he uses much of this in baking a large loaf; but he so
arranges matters by a clever contrivance that part of the original
leaven is always carried on unaltered, carefully preserved for the next
baking. Nature is the baker, the loaf is the body, the leaven is the
germ-plasm, and each baking is a generation. "
When the respective functions and relative importance, from a genetic
point of view, of germ-plasm and body-plasm are understood, it must be
fairly evident that the natural point of attack for any attempt at race
betterment which aims to be fundamental rather than wholly superficial,
must be the germ-plasm rather than the body-plasm. The failure to hold
this point of view has been responsible for the disappointing results of
much of the sociological theory of the last century, and for the fact
that some of the work now carried on under the name of race betterment
is producing results that are of little or no significance to true race
betterment.
On the other hand, it must be fairly evident, from the pains which
Nature has taken to arrange for the transmission of the germ-plasm from
generation to generation, that she would also protect it from injury
with meticulous care. It seems hardly reasonable to suppose that a
material of this sort should be exposed, in the higher animals at least,
to all the vicissitudes of the environment, and to injury or change from
the chance of outward circumstances.
In spite of these presumptions which the biologist would, to say the
least, consider worthy of careful investigation, the world is full of
well-intentioned people who are anxious to improve the race, and who in
their attempts to do so, wholly ignore the germ-plasm. They see only the
body-plasm. They are devoted to the dogma that if they can change the
body (and what is here said of the body applies equally to the mind) in
the direction they wish, this change will in some unascertainable way be
reproduced in the next generation. They rarely stop to think that man is
an animal, or that the science of biology might conceivably have
something to say about the means by which his species can be improved;
but if they do, they commonly take refuge, deliberately or
unconsciously, in the biology of half a century ago, which still
believed that these changes of the body could be so impressed on the
germ-plasm as to be continued in the following generation.
Such an assumption is made to-day by few who have thoroughly studied the
subject. Even those who still believed in what is conventionally called
"the inheritance of acquired characteristics" would be quick to
repudiate any such application of the doctrine as is commonly made by
most of the philanthropists and social workers who are proceeding
without seeking the light of biology. But the idea that these
modifications are inherited is so widespread among all who have not
studied biology, and is so much a part of the tradition of society, that
the question must be here examined, before we can proceed confidently
with our program of eugenics.
The problem is first to be defined.
It is evident that all characters which make up a man or woman, or any
other organism, must be either germinal or acquired. It is impossible to
conceive of any other category. But it is frequently hard to say in
which class a given character falls. Worse still, many persons do not
even distinguish the two categories accurately--a confusion made easier
by the quibble that _all_ characters must be acquired, since the
organism starts from a single cell, which possesses practically none of
the traits of the adult.
What we mean by an inborn character is one whose expression is due to
something which is present in the germ-plasm; one which is inherent and
due to heredity. An acquired character is simply a modification, due to
some cause external to the germ-plasm acting on an inborn character. In
looking at an individual, one can not always say with certainty which
characters are which; but with a little trouble, one can usually reach a
reliable decision. It is possible to measure the variation in a given
character in a group of parents and their children, in a number of
different environments; if the degree of resemblance between parent and
offspring is about the same in each case, regardless of the different
surroundings in which the children may have been brought up, the
character may properly be called germinal. This is the biometric method
of investigation. In practice, one can often reach a decision by much
simpler means: if the character is one that appears at birth, e. g. ,
skin color, it is usually safe to assume that it is a germinal
character, unless there is some evident reason for deciding otherwise,
as in the case of a child born with some disease from which the mother
had been suffering for the previous few months. In general, it is more
difficult to decide whether a mental trait is germinal, than whether a
physical one is; and great care should be used in classification.
To make the distinction, one ought to be familiar with an individual
from birth, and to have some knowledge of the conditions to which he was
exposed, in the period between conception and birth,--for of course a
modification which takes place during that time is as truly an acquired
character as one that takes place after parturition. Blindness, for
example, may be an inborn defect. The child from conception may have
lacked the requisites for the development of sight. On the other hand,
it may be an acquired character, due to an ill-advised display of
patriotism on July 4, at some time during childhood; or even to
infection at the moment of birth. Similarly small size may be an inborn
character, due to a small-sized ancestry; but if the child comes of a
normal ancestry and is stunted merely because of lack of proper care and
food, the smallness is an acquired character. Deafness may be congenital
and inborn, or it may be acquired as the result, say, of scarlet fever
during childhood.
Now the inborn characters (excepting modifications _in utero_) are
admittedly heritable, for inborn characters must exist potentially in
the germ-plasm. The belief that acquired characters are also inherited,
therefore, involves belief that in some way the trait acquired by the
parent is incorporated in the germ-plasm of the parent, to be handed on
to the child and reappear in the course of the child's development. The
impress on the parental _body_ must in some way be transferred to the
parental _germ-plasm_; and not as a general influence, but as a specific
one which can be reproduced by the germ-plasm.
This idea was held almost without question by the biologists of the
past, from Aristotle on. Questionings indeed arose from time to time,
but they were vague and carried no weight, until a generation ago
several able men elaborated them. For many years, it was the question of
chief dispute in the study of heredity. The last word has not yet been
said on it. It has theoretical bearings of immense importance; for our
conception of the process of evolution will be shaped according to the
belief that acquired characters are or are not inherited. Herbert
Spencer went so far as to say, "Close contemplation of the facts
impresses me more strongly than ever with two alternatives--either that
there has been inheritance of acquired characters, or there has been no
evolution. " But its practical bearings are no less momentous. Again to
quote Spencer: "Considering the width and depth of the effects which the
acceptance or non-acceptance of one or the other of these hypotheses
must have on our views of life, the question, Which of them is true?
demands beyond all other questions whatever the attention of scientific
men. A grave responsibility rests on biologists in respect of the
general question, since wrong answers lead, among other effects, to
wrong belief about social affairs and to disastrous social actions. "
Biologists certainly have not shirked this "grave responsibility" during
the last 30 years, and they have, in our opinion, satisfactorily
answered the general question. The answer they give is not the answer
Herbert Spencer gave.
But the popular mind frequently lags a generation behind, in its grasp
of the work of science, and it must be said that in this case the
popular mind is still largely under the influence of Herbert Spencer and
his school. _Whether they know it or not_, most people who have not made
a particular study of the question still tacitly assume that the
acquirements of one generation form part of the inborn heritage of the
next, and the present social and educational systems are founded in
large part on this false foundation. Most philanthropy starts out
unquestioningly with the assumption that by modifying the individual for
the better, it will thereby improve the germinal quality of the race.
Even a self-styled eugenist asks, "Can prospective parents who have
thoroughly and systematically disciplined themselves, physically,
mentally and morally, transmit to their offspring the traits or
tendencies which they have developed? " and answers the question with the
astounding statement, "It seems reasonable to suppose that they have
this power, it being simply a phase of heredity, the tendency of like to
beget like.
"
The right understanding of this famous problem is therefore fraught with
the most important consequences to eugenics. The huge mass of
experimental evidence that has been accumulated during the last quarter
of a century has, necessarily, been almost wholly based on work with
plants and lower animals. Even though we can not attempt to present a
general review of this evidence, for which the reader must consult one
of the standard works on biology or genetics, we shall point out some of
the considerations underlying the problem and its solution.
In the first place, it must be definitely understood that we are dealing
only with specific, as distinguished from general, transmission. As the
germ-cells derive their nourishment from the body, it is obvious that
any cause profoundly affecting the latter might in that way exercise an
influence on the germ-cells; that if the parent was starved, the
germ-cells might be ill-nourished and the resulting offspring might be
weak and puny. There is experimental evidence that this is the case; but
that is not the inheritance of an acquired character. If, however, a
white man tanned by long exposure to the tropical sun should have
children who were brunettes, when the family stock was all blond; or if
men whose legs were deformed through falls in childhood should have
children whose legs, at birth, appeared deformed in the same manner;
then there would be a distinct case of the transmission of an acquired
characteristic. "The precise question," as Professor Thomson words it,
"is this: Can a structural change in the body, induced by some change in
use or disuse, or by a change in surrounding influence, affect the
germ-cells in such a _specific_ or representative way that the offspring
will through its inheritance exhibit, even in a slight degree, the
modification which the parent acquired? " He then lists a number of
current misunderstandings, which are so widespread that they deserve to
be considered here.
(1) It is frequently argued (as Herbert Spencer himself suggested) that
unless modifications are inherited, there could be no such thing as
evolution. Such pessimism is unwarranted. There _is_ abundant
explanation of evolution, in the abundant supply of germinal variations
which every individual presents.
(2) It is common to advance an _interpretation_ of some observation, in
support of the Lamarckian doctrine, as if it were a _fact_.
Interpretations are not facts. What is wanted are the facts; each
student has a right to interpret them as he sees fit, but not to
represent his interpretation as a fact. It is easy to find structural
features in Nature which _may be interpreted_ as resulting from the
inheritance of acquired characters; but this is not the same as to say
and to prove that they _have resulted_ from such inheritance.
(3) It is common to beg the question by pointing to the transmission of
some character that is not proved to be a modification. Herbert Spencer
cited the prevalence of short-sightedness among the "notoriously
studious" Germans as a defect due to the inheritance of an acquired
character. But he offered no evidence that this is an acquirement rather
than a germinal character. As a fact, there is reason to believe that
weakness of the eyes is one of the characteristics of that race, and
existed long before the Germans ever became studious--even at a time
when most of them could neither read nor write.
(4) The reappearance of a modification may be mistaken for the
transmission of a modification. Thus a blond European family moves to
the tropics, and the parents become tanned. The children who grow up
under the tropical sun are tanned from infancy; and after the
grandchildren or great-grandchildren appear, brown from childhood, some
one points to the case as an instance of permanent modification of
skin-color. But of course the children at the time of birth are as white
as their distant cousins in Europe, and if taken back to the North to be
brought up, would be no darker than their kinsmen who had never been in
the tropics. Such "evidence" has often been brought forward by careless
observers, but can deceive no one who inquires carefully into the facts.
(5) In the case of diseases, re-infection is often mistaken for
transmission. The father had pneumonia; the son later developed it;
ergo, he must have inherited it. What evidence is there that the son in
this case did not get it from an entirely different source? Medical
literature is heavily burdened with such spurious evidence.
(6) Changes in the germ-cells _along with_ changes in the body are not
relevant to this discussion. The mother's body, for example, is poisoned
with alcohol, which is present in large quantities in the blood and
therefore might affect the germ-cells directly. If the children
subsequently born are consistently defective it is not an inheritance of
a body character but the result of a direct modification of the
germ-plasm. The inheritance of an acquired modification of the body can
only be proved if some particular change made in the parent is inherited
as such by the child.
(7) There is often a failure to distinguish between the possible
inheritance of a particular modification, and the possible inheritance
of indirect results of that modification, or of changes correlated with
it. This is a nice but crucial point on which most popular writers are
confused. Let us examine it through a hypothetical case. A woman, not
herself strong, bears a child that is weak. The woman then goes in for
athletics, in order better to fit herself for motherhood; she
specializes on tennis. After a few years she bears another child, which
is much stronger and better developed than the first. "Look," some one
will say, "how the mother has transmitted her acquirement to her
offspring. " We grant that her improved general health will probably
result in a child that is better nourished than the first; but that is a
very different thing from heredity. If, however, the mother had played
tennis until her right arm was over-developed, and her spine bent; if
these characteristics were nowhere present in the ancestry and not seen
in the first child; but if the second child were born with a bent spine
and a right arm of exaggerated musculature, we would be willing to
consider the case on the basis of the inheritance of an acquired
character. We are not likely to have such a case presented to us.
To put the matter more generally, it is not enough to show that _some_
modification in the parent results in _some_ modification in the child.
For the purposes of this argument there must be a similar modification.
(8) Finally, data are frequently presented, which cover only two
generations--parent and child. Indeed, almost all the data alleged to
show the inheritance of acquired characteristics are of this kind. They
are of little or no value as evidence. Cases covering a number of
generations, where a _cumulative_ change was visible, would be of
weight, but on the rare occasions when they are forthcoming, they can be
explained in some other way more satisfactorily than by an appeal to the
theory of Lamarck. [13]
If the evidence currently offered to support a belief in the inheritance
of acquired characters is tested by the application of these
"misunderstandings," it will at once be found that most of it
disappears; that it can be thrown out of court without further
formality. The Lamarckian doctrine is now held mainly by persons who
have either lacked training in the evaluation of evidence, or have never
examined critically the assumptions on which they proceed. Medical men
and breeders of plants or animals are to a large extent believers in
Lamarckism, but the evidence (if any) on which they rely is always
susceptible of explanation in a more reasonable way. It must not be
forgotten that some of the ablest intellects in the world have been
assidously engaged in getting at the truth in the case, during the last
half-century; and it is certainly worthy of consideration that not in a
single case has the transmission of an acquired body character ever
been proved beyond dispute. Those who still hold a belief in it (and it
is fair to say that some men of real ability are among that number) too
often do so, it is to be feared, because it is necessary for the support
of some theoretical doctrine which they have formulated. Certainly there
are few men who can say that they have carefully examined the evidence
in the case, and accept Lamarckism because the evidence forces them to
do so. It will be interesting to review the various classes of alleged
evidence, though we can cite only a few cases from the great number
available (most of them, however, dealing with plants or lower animals).
Nearly all the evidence adduced can be put in one of these four classes:
(1) Mutilations.
(2) Diseases.
(3) Results of use or disuse.
(4) Physico-chemical effects of environment.
The case in regard to mutilations is particularly clear cut and leaves
little room for doubt. The noses and ears of oriental women have been
pierced for generations without number, yet girls are still born with
these parts entire. Circumcision offers another test case. The evidence
of laboratory experiments (amputation of tails) shows no inheritance. It
may be said without hesitation that mutilations are not heritable, no
matter how many generations undergo them.
(2) The transmissibility of acquired diseases is a question involved in
more of a haze of ignorance and loose thinking. It is particularly
frequent to see cases of uterine infection offered as cases of the
inheritance of acquired characters. To use the word "heredity" in such a
case is unjustified. Uterine infection has no bearing whatever on the
question.
Taking an historical view, it seems fairly evident that if diseases were
really inherited, the race would have been extinct long ago. Of course
there are constitutional defects or abnormalities that are in the
germ-plasm and are heritable: such is the peculiar inability of the
blood to coagulate, which marks "bleeders" (sufferers from hemophilia, a
highly hereditary disease). And in many cases it is difficult to
distinguish between a real germinal condition of this sort, and an
acquired disease.
The inheritance of an acquired disease is not only inconceivable, in the
light of what is known about the germ-plasm, but there is no evidence to
support it. While there is most decidedly such a thing as the
inheritance of a tendency to or lack of resistance to a disease, it is
not the result of incidence of the disease on the parent. It is possible
to inherit a tendency to headaches or to chronic alcoholism; and it is
possible to inherit a lack of resistance to common diseases such as
malaria, small-pox or measles; but actually to inherit a zymotic disease
as an inherent genetic trait, is impossible,--is, in fact, a
contradiction of terms.
(3) When we come to the effects of use and disuse, we reach a much
debated ground, and one complicated by the injection of a great deal of
biological theorizing, as well as the presence of the usual large amount
of faulty observation and inference.
It will be admitted by every one that a part of the body which is much
used tends to increase in size, or strength, and similarly that a part
which is not used tends to atrophy. It is further found that such
changes are progressive in the race, in many cases. Man's brain has
steadily increased in size, as he used it more and more; on the other
hand, his canine teeth have grown smaller. Can this be regarded as the
inheritance of a long continued process of use and disuse? Such a view
is often taken, but the Lamarckian doctrine seems to us just as mystical
here as anywhere else, and no more necessary. Progressive changes can be
satisfactorily accounted for by natural selection; retrogressive changes
are susceptible of explanation along similar lines. When an organ is no
longer necessary, as the hind legs of a whale, for instance, natural
selection no longer keeps it at the point of perfection. Variation,
however, continues to occur in it. Since the organ is now useless,
natural selection will no longer restrain variation in such an organ,
and degeneracy will naturally follow, for of all the variations that
occur in the organ, those tending to loss are more numerous than those
tending to addition. If the embryonic development of a whale's hind leg
be compared to some complicated mechanical process, such as the
manufacture of a typewriter, it will be easier to realize that a trivial
variation which affected one of the first stages of the process would
alter all succeeding stages and ruin the final perfection of the
machine. It appears, then, that progressive degeneration of an organ can
be adequately explained by variation with the removal of natural
selection, and that it is not necessary or desirable to appeal to any
Lamarckian factor of an unexplainable and undemonstrable nature.
The situation remains the same, when purely mental processes, such as
instincts, are considered. Habit often repeated becomes instinctive, it
is said; and then the instinct thus formed by the individual is passed
on to his descendants and becomes in the end a racial instinct. Most
psychologists have now abandoned this view, which receives no support
from investigation. Such prevalence as it still retains seems to be
largely due to a confusion of thought brought about by the use of the
word "instinctive" in two different senses,--first literally and then
figuratively.
A persistent attempt has been made in America during recent years, by
C. L. Redfield, a Chicago engineer, to rehabilitate the theory of the
inheritance of the effects of use and disuse. He has presented it in a
way that, to one ignorant of biology, appears very exact and plausible;
but his evidence is defective and his interpretation of his evidence
fallacious. Because of the widespread publicity, Mr. Redfield's work has
received, we discuss it further in Appendix B.
Since the importance of hormones (internal secretions) in the body
became known, it has often been suggested that their action may furnish
the clue to some sort of an inheritance of modifications. The hormone
might conceivably modify the germ-plasm but if so, it would more likely
be in some wholly different way.
In general, we may confidently say that there is neither theoretical
necessity nor adequate experimental proof for belief that the results of
use and disuse are inherited.
(4) When we come to consider whether the effects of the environment are
inherited, we attack a stronghold of sociologists and historians.
Herbert Spencer thought one of the strongest pieces of evidence in this
category was to be found in the assimilation of foreigners in the United
States. "The descendants of the immigrant Irish," he pointed out, "lose
their Celtic aspect and become Americanised. . . . To say that 'spontaneous
variation,' increased by natural selection, can have produced this
effect, is going too far. " Unfortunately for Mr. Spencer, he was basing
his conclusions on guesswork. It is only within the last few months that
the first trustworthy evidence on the point has appeared, in the careful
measurements of Hrdlicka who has demonstrated that Spencer was quite
wrong in his statement. As a fact, the original traits persist with
almost incredible fidelity. (Appendix C. )
In 1911, Franz Boas of Columbia University published measurements of the
head form of children of immigrants[14] which purported to show that
American conditions caused in some mysterious manner a change in the
shape of the head. This conclusion in itself would have been striking
enough, but was made more startling when he announced that the change
worked both ways: "The East European Hebrew, who has a very round head,
becomes more long-headed; the south Italian, who in Italy has an
exceedingly long head, becomes more short-headed"; and moreover this
potent influence was alleged to be a subtle one "which does not affect
the young child born abroad and growing up in American environment, but
which makes itself felt among the children born in America, even a short
time after the arrival of the parents in this country. " Boas' work was
naturally pleasing to sociologists who believe in the reality of the
"melting-pot," and has obtained widespread acceptance in popular
literature. It has obtained little acceptance among his
fellow-anthropologists, some of whom allege that it is unsound because
of the faulty methods by which the measurements were made and the
incorrect standards used for comparison.
The many instances quoted by historians, where races have changed after
immigration, are to be explained in most cases by natural selection
under new conditions, or by interbreeding with the natives, and not as
the direct result of climate. Ellsworth Huntington, the most recent and
careful student of the effect of climate on man,[15] finds that climate
has a great deal of influence on man's energy, but as far as inherited
traits in general are concerned, he is constantly led to remark how
little heredity is capable of being changed.
Most members of the white race have little toes that are partly
atrophied, and considerably deformed. In many cases one of the joints
has undergone ankylosis--that is, the bones have coalesced. It is
confidently alleged that this is due to the inheritance of the effects
of wearing tight shoes through many centuries. When it is found that the
prehistoric Egyptians, who knew not tight shoes, suffered from the same
defect in a similar degree, one's confidence in this kind of evidence is
much diminished.
The retrogression of the little toe in man is probably to be explained
like the degeneration of the hind leg of the whale, as a result of the
excess of deteriorating variations which, when not eliminated by natural
selection, lead to atrophy. Since man began to limit the use of his feet
to walking on the ground, the little toe has had much less value to him.
The feet of Chinese women offer another illustration along this line.
Although they have been tightly bound for many generations, no deformity
is apparent in the feet of girl babies.
Breeders are generally of the opinion that good care and feed bestowed
on their stock produce results in succeeding generations. This is in a
way true, but it is due merely to the fact that the offspring get better
nourishment and therefore a better start in life. The changes in breeds,
the increase in milk yield, and similar facts, often explained as due to
inheritance of acquired characters, are better explained as the results
of selection, sometimes conscious, sometimes quite unconscious.
[Illustration: BOUND FOOT OF A CHINESE WOMAN
FIG. 5. --For centuries the feet of upper class women, and many
lower class women, in China have been distorted in this manner; but
their daughters have perfect feet when born. ]
[Illustration: DEFECTIVE LITTLE TOE OF A PREHISTORIC EGYPTIAN
FIG. 6. --The above illustration shows the foot of a prehistoric
Egyptian who is estimated to have lived about 8000 B. C. The last joint
of the little toe had entirely disappeared, and careful dissection
leaves no doubt that it was a germinal abnormality, such as is
occasionally seen to-day, and not the result of disease. It is,
therefore, evident that the degeneration of man's little toe must be
ascribed to some more natural cause than the wearing of shoes for many
generations. Photograph from Dr. Gorgy Sobhy, School of Medicine,
Cairo. ]
The question of inherited immunity to diseases, as the result of
vaccination or actual illness from them, has appeared in the controversy
in a number of forms, and is a point of much importance. It is not yet
clear, partly because the doctors disagree as to what immunity is. But
there is no adequate evidence that an immunity to anything can be
created and transmitted through the germ-plasm to succeeding
generations.
In short, no matter what evidence we examine, we must conclude that
inheritance of acquired bodily characters is not a subject that need be
reckoned with, in applied eugenics.
On the other hand, there is a possible indirect influence of
modifications, which may have real importance in man. If the individual
is modified in a certain way, in a number of generations, even though
such a modification is not transmitted to his descendants, yet its
continued existence may make possible, the survival of some germinal
variation bearing in the same direction, which without the protecting
influence of the pre-existing modification, would have been swamped or
destroyed.
Finally, it should be borne in mind that even if physical and mental
characters acquired during a man's lifetime are not transmitted, yet
there is a sort of transmission of acquired characters which has been of
immense importance to the evolution of the race. This is the so-called
"inheritance" of the environment; the passing on from one generation to
the next of the achievements of the race, its accumulated social
experience; its civilization, in short. It is doubtful whether any
useful end is gained by speaking of this continuance of the environment
as "heredity;" it certainly tends to confuse many people who are not
used to thinking in biological terms. Tradition is the preferable term.
There is much to be said in favor of E. B. Poulton's
definition,--"Civilization in general is the sum of those contrivances
which enable human beings to advance independently of heredity. "
Whatever wisdom, material gain, or language is acquired by one
generation may be passed on to the next. As far as the environment is
concerned, one generation stands on the shoulders of its predecessor.
It might simplify the task of eugenics if the same could be said of
biological heredity. But it can not. Each generation must "start from
scratch. "
In August Weismann's words, the development of a function in offspring
begins at the point where it _began_ in his parents, not at the point
where it _ended_ in them. Biological improvement of the race (and such
improvement greatly fosters all other kinds) must be made through a
selective birth-rate. There is no short-cut by way of euthenics, merely.
We must now consider whether there is any direct way of impairing good
heredity. It is currently believed that there are certain substances,
popularly known as "racial-poisons," which are capable of affecting the
germ-plasm adversely and permanently in spite of its isolation and
protection. For example, the literature of alcoholism, and much of the
literature of eugenics, abounds with statements to the effect that
alcohol _originates_ degeneracy in the human race.
The proof or disproof of this proposition must depend in the last
analysis on direct observation and carefully controlled experiments. As
the latter cannot be made feasibly on man, a number of students have
taken up the problem by using small animals which are easily handled in
laboratories. Many of these experiments are so imperfect in method that,
when carefully examined, they are found to possess little or no value as
evidence on the point here discussed.
Hodge, Mairet and Combemale, for example, have published data which
convinced them that the germ-plasm of dogs was injured by the
administration of alcohol. The test was the quality of offspring
directly produced by the intoxicated animals under experiment. But the
number of dogs used was too small to be conclusive, and there was no
"control": hence these experiments carry little weight.
Ovize, Fere and Stockard have shown that the effect of alcohol on hen's
eggs is to produce malformed embryos. This, however, is a case of
influencing the development of the individual, rather than the
germ-plasm. Evidence is abundant that individual development can be
harmed by alcohol, but the experiments with eggs are not to the point
of our present purpose.
Carlo Todde and others have carried out similar experiments on cocks.
The conclusions have in general been in favor of injury to the
germ-plasm, but the experiments were inadequate in extent.
Laitinen experimented on rabbits and guinea pigs, but he used small
doses and secured only negative results.
Several series of experiments with rats indicate that if the dosage is
large enough, the offspring can be affected.
Nice, using very small numbers of white mice, subjected them not only to
alcohol, but to caffein, nicotin, and tobacco smoke. The fecundity of
all these sets of mice was higher than that of the untreated ones used
as control; all of them gained in weight; of 707 young, none was
deformed, none stillborn, and there was only one abortion. The young of
the alcoholized mice surpassed all others in growth. The dosage Nice
employed was too small, however, to give his experiment great weight.
At the University of Wisconsin, Leon J. Cole has been treating male
rabbits with alcohol and reports that "what appear to be decisive
results have already been obtained. In the case of alcoholic poisoning
of the male the most marked result has been a lessening of his
efficiency as a sire, the alcohol apparently having had some effect on
the vitality of his spermatozoa. " His experiment is properly planned and
carried out, but so far as results have been made public, they do not
appear to afford conclusive evidence that alcohol originates degeneracy
in offspring.
The long-continued and carefully conducted experiment of Charles R.
Stockard at the Cornell Medical College is most widely quoted in this
connection. He works with guinea-pigs. The animals are intoxicated
daily, six days in the week, by inhaling the fumes of alcohol to the
point where they show evident signs of its influence; their condition
may thus be compared to that of the toper who never gets "dead drunk"
but is never entirely sober. Treatment of this sort for a period as long
as three years produces no apparent bad effect on the individuals; they
continue to grow and become fat and vigorous, taking plenty of food and
behaving in a normal manner in every particular. Some of them have been
killed from time to time, and all the tissues, including the
reproductive glands, have been found perfectly normal. "The treated
animals are, therefore, little changed or injured so far as their
behavior and structure goes. Nevertheless, the effects of the treatment
are most decidedly indicated by the type of offspring to which they give
rise, whether they are mated together or with normal individuals. "
Before the treatment is begun, every individual is mated at least once,
to demonstrate its possibility of giving rise to sound offspring. The
crucial test of the influence of alcohol on the germ-cells is, of
course, the mating of a previously alcoholized male with a normal,
untreated female, in a normal environment.
When the experiment was last reported,[16] it had covered five years and
four generations. The records of 682 offspring produced by 571 matings
were tabulated, 164 matings of alcoholized animals, in which either the
father, mother, or both were alcoholic, gave 64, or almost 40%, negative
results or early abortions, while only 25% of the control matings failed
to give full-term litters. Of the 100 full-term litters from alcoholic
parents 18% contained stillborn young and only 50% of all the matings
resulted in living litters, while 47% of the individuals in the litters
of living young died soon after birth. In contrast to this record 73% of
the 90 control matings gave living litters and 84% of the young in these
litters survived as normal, healthy animals.
"The mating records of the descendants of the alcoholized guinea pigs,
although they themselves were not treated with alcohol, compare in some
respects even more unfavorably with the control records than do the
above data from the directly alcoholized animals. " The records of the
matings in the second filial generation "are still worse, higher
mortality and more pronounced deformities, while the few individuals
which have survived are generally weak and in many instances appear to
be quite sterile even though paired with vigorous, prolific, normal
mates.
in general there have been wars going on during the whole period of
modern European history; there have always been opportunities for a
royal hero to make his appearance; but often the country has called for
many years in vain. Circumstances were powerless to produce a great man
and the nation had to wait until heredity produced him. Spain has for
several centuries been calling for genius in leadership in some lines;
but in vain. England could not get an able man from the Stuart line,
despite her need, and had to wait for William of Orange, who was a
descendant of a man of genius, William the Silent. "Italy had to wait
fifty years in bondage for her deliverers, Cavour, Garibaldi and Victor
Emmanuel. "
"The upshot of it all," Dr. Woods decides, "is that, as regards
intellectual life, environment is a totally inadequate explanation. If
it explains certain characters in certain instances, it always fails to
explain many more, while heredity not only explains all, or at least
90%, of the intellectual side of character in practically every
instance, but does so best when questions of environment are left out of
discussion. "
Despite the good environment almost uniformly present, the geniuses in
royalty are not scattered over the surface of the pedigree chart, but
form isolated little groups of closely related individuals. One centers
in Frederick the Great, another in Queen Isabella of Spain, a third in
William the Silent, and a fourth in Gustavus Adolphus. Furthermore, the
royal personages who are conspicuously low in intellect and morality are
similarly grouped. Careful study of the circumstances shows nothing in
the environment that would produce this grouping of genius, while it is
exactly what a knowledge of heredity leads one to expect.
In the next place, do the superior members of royalty have
proportionately more superior individuals among their close relatives,
as was found to be the case among the Americans in the Hall of Fame? A
count shows at once that they do. The first six grades all have about an
equal number of eminent relatives, but grade 7 has more while grade 8
has more than grade 7, and the geniuses of grade 10 have the highest
proportion of nearer relatives of their own character. Surely it cannot
be supposed that a relative of a king in grade 8 has on the average a
much less favorable environment than a relative of a king in grade 10.
Is it not fair, then, to assume that this relative's greater endowment
in the latter case is due to heredity?
Conditions are the same, whether males or females be considered. The
royal families of Europe offer a test case because for them the
environment is nearly uniformly favorable. A study of them shows great
mental and moral differences between them, and critical evidence
indicates that these differences are largely due to differences in
heredity. Differences of opportunity do not appear to be largely
responsible for the achievements of the individuals.
But, it is sometimes objected, opportunity certainly is responsible for
the appearance of much talent that would otherwise never appear. Take
the great increase in the number of scientific men in Germany during the
last half century, for example. It can not be pretended that this is due
to an increased birth-rate of such talent; it means that the growth of
an appreciation of scientific work has produced an increased amount of
scientific talent. J. McKeen Cattell has argued this point most
carefully in his study of the families of one thousand American men of
science (_Popular Science Monthly_, May, 1915). "A Darwin born in China
in 1809," he says, "could not have become a Darwin, nor could a Lincoln
born here on the same day have become a Lincoln had there been no Civil
War. If the two infants had been exchanged there would have been no
Darwin in America and no Lincoln in England. " And so he continues,
urging that in the production of scientific men, at least, education is
more important than eugenics.
This line of argument contains a great deal of obvious truth, but is
subject to a somewhat obvious objection, if it is pushed too far. It is
certainly true that the exact field in which a man's activities will
find play is largely determined by his surroundings and education. Young
men in the United States are now becoming lawyers or men of science, who
would have become ministers had they been born a century or two ago. But
this environmental influence seems to us a minor one, for the man who is
highly gifted in some one line is usually, as all the work of
differential psychology shows, gifted more than the average in many
other lines. Opportunity decides in just what field his life work shall
lie; but he would be able to make a success in a number of fields.
Darwin born in America would probably not have become the Darwin we
know, but it is not to be supposed that he would have died a "mute,
inglorious Milton": it is not likely that he would have failed to make
his mark in some line of human activity. Dr. Cattell's argument, then,
while admissible, can not properly be urged against the fact that
ability is mainly dependent on inheritance.
We need not stop with the conclusion that equality of training or
opportunity is unable to level the inborn differences between men. We
can go even farther, and produce evidence to show that equality of
training _increases the differences_ in results achieved.
This evidence is obtained by measuring the effects of equal amounts of
exercise of a function upon individual differences in respect to
efficiency in it. Suppose one should pick out, at random, eight
children, and let them do problems in multiplication for 10 minutes.
After a number of such trials, the three best might average 39 correct
solutions in the 10 minutes, and the three poorest might average 25
examples. Then let them continue the work, until each one of them has
done 700 examples. Here is equality in training; does it lead to uniform
results?
Dr. Starch made the actual test which we have outlined and found that
the three best pupils gained on the average 45 in the course of doing
700 examples; while the three poorest gained only 26 in the same course
of time.
Similar tests have been made of school children in a number of
instances, and have shown that equality of training fails to bring about
equality of performance. All improve to some extent; but those who are
naturally better than their comrades usually become better still, when
conditions for all are the same. E. L. Thorndike gives[12] the following
tabular statement of a test he conducted:
THE EFFECT OF EQUAL AMOUNTS OF PRACTICE UPON INDIVIDUAL DIFFERENCES
IN THE MENTAL MULTIPLICATION OF A THREE-PLACE BY A THREE-PLACE
NUMBER
Amount done Percentage of
per unit of correct figures
time in answers
Hours of Practice
|
| First 5 Examples First 5 Examples
| | |
| | Last 5 or 10 | Last 5 or 10
| | Examples | Examples
| | | | |
| | | Gain | | Gain
Initial highest five individuals 5. 1 85 147 61 70 78 18
" next five " 5. 1 56 107 51 68 78 10
" " six " 5. 3 46 68 22 74 82 8
" " six " 5. 4 38 46 8 58 70 12
" " five " 5. 2 31 57 26 47 67 20
" " one individual 5. 2 19 32 13 100 82 -18
Similar results have been obtained by half a dozen other experimenters,
using the tests of mental multiplication, addition, marking A's on a
printed sheet of capitals, and the like. It would be a mistake to
conclude too much from experiments of such restricted scope; but they
all agree in showing that if every child were given an equal training,
the differences in these traits would nevertheless be very great.
And although we do not wish to strain the application of these results
too far, we are at least justified in saying that they strongly indicate
that inborn mediocrity can not be made into a high grade of talent by
training. Not every boy has a chance to distinguish himself, even if he
receives a good education.
We are driven back to the same old conclusion, that it is primarily
inborn nature which causes the achievements of men and women to be what
they are. Good environment, opportunity, training, will give good
heredity a chance to express itself; but they can not produce greatness
from bad heredity.
These conclusions are familiar to scientific sociologists, but they have
not yet had the influence on social service and practical attempts at
reform which they deserve. Many popular writers continue to confuse
cause and effect, as for example H. Addington Bruce, who contributed an
article to the _Century Magazine_, not long ago, on "The Boy Who Goes
Wrong. " After alleging that the boy who goes wrong does so because he is
not properly brought up, Mr. Bruce quotes with approval the following
passage from Paul Dubois, "the eminent Swiss physician and philosopher:
"If you have the happiness to be a well-living man, take care not to
attribute the credit of it to yourself. Remember the favorable
conditions in which you have lived, surrounded by the relatives who
loved you and set you a good example; do not forget the close friends
who have taken you by the hand and led you away from the quagmires of
evil; keep a grateful remembrance for all the teachers who have
influenced you, the kind and intelligent school-master, the devoted
pastor; realize all these multiple influences which have made you what
you are. Then you will remember that such and such a culprit has not in
his sad life met with these favorable conditions; that he had a drunken
father or a foolish mother, and that he has lived without affection,
exposed to all kinds of temptation. You will then take pity upon this
disinherited man, whose mind has been nourished upon malformed mental
images, begetting evil sentiments such as immoderate desire or social
hatred. "
Mr. Bruce indorses this kind of talk when he concludes, "The blame for
the boy who goes wrong does not rest with the boy himself, or yet with
his remote ancestors. It rests squarely with the parents who, through
ignorance or neglect, have failed to mold him aright in the plastic days
of childhood. "
Where is the evidence of the existence of these plastic days of
childhood? If they exist, why do not ordinary brothers become as much
alike as identical twins? How long are we to be asked to believe, on
blind faith, that the child is putty, of which the educator can make
either mediocrity or genius, depending on his skill? What does the
environmentalist _know_ about these "plastic days"? If a boy has a
drunken father or foolish mother, does it not suggest that there is
something wrong with his pedigree? With such an ancestry, we do not
expect him to turn out brilliantly, no matter in what home he is brought
up. If a boy has the kind of parents who bring him up well; if he is,
as Dr. Dubois says, surrounded by relatives who love him and set him a
good example, we at once have ground for a suspicion that he comes of a
pretty good family, a stock characterized by a high standard of
intellectuality and morality, and it would surprise us if such a boy did
not turn out well. But he turns out well because what's bred in the bone
will show in him, if it gets any kind of a chance. It is his nature, not
his nurture, that is mainly responsible for his character.
CHAPTER II
MODIFICATION OF THE GERM-PLASM
Every living creature was at some stage of its life nothing more than a
single cell. It is generally known that human beings result from the
union of an egg-cell and a sperm-cell, but it is not so universally
understood that these germ-cells are part of a continuous stream of
germ-plasm which has been in existence ever since the appearance of life
on the globe, and which is destined to continue in existence as long as
life remains on the globe.
The corollaries of this fact are of great importance. Some of them will
be considered in this chapter.
Early investigators tended naturally to look on the germ-cells as a
product of the body. Being supposedly products of the body, it was
natural to think that they would in some measure reproduce the character
of the body which created them; and Darwin elaborated an ingenious
hypothesis to explain how the various characters could be represented in
the germ-cell. The idea held by him, in common with most other thinkers
of his period, is still held more or less unconsciously by those who
have not given particular attention to the subject. Generation is
conceived as a direct chain: the body produces the germ-cell which
produces another body which in turn produces another germ-cell, and so
on.
But a generation ago this idea fell under suspicion. August Weismann,
professor of zoology in the University of Freiburg, Germany, made
himself the champion of the new idea, about 1885, and developed it so
effectively that it is now a part of the creed of nearly every
biologist.
Weismann caused a general abandonment of the idea that the germ-cell is
produced by the body in each generation, and popularized the conception
of the germ-cell as a product of a stream of undifferentiated
germ-plasm, not only continuous but (potentially at least) immortal.
The body does not produce the germ-cells, he pointed out; instead, the
germ-cells produce the body.
The basis of this theory can best be understood by a brief consideration
of the reproduction of very simple organisms.
"Death is the end of life," is the belief of many other persons than the
Lotus Eaters. It is commonly supposed that everything which lives must
eventually die. But study of a one-celled animal, an Infusorian, for
example, reveals that when it reaches a certain age it pinches in two,
and each half becomes an Infusorian in all appearance identical with the
original cell. Has the parent cell then died? It may rather be said to
survive, in two parts. Each of these daughter cells will in turn go
through the same process of reproduction by simple fission, and the
process will be continued in their descendants. The Infusorian can be
called potentially immortal, because of this method of reproduction.
The immortality, as Weismann pointed out, is not of the kind attributed
by the Greeks to their gods, who could not die because no wound could
destroy them. On the contrary, the Infusorian is extremely fragile, and
is dying by millions at every instant; but if circumstances are
favorable, it _can_ live on; it is not inevitably doomed to die sooner
or later, as is Man. "It dies from accident often, from old age never. "
Now the single-celled Infusorian is in many respects comparable with the
single-celled germ of the higher animals. The analogy has often been
carried too far; yet it remains indisputable that the germ-cells of men
reproduce in the same way--by simple fission--as the Infusorian and
other one-celled animals and plants, and that they are organized on much
the same plan. Given favorable circumstances, the germ-cell should be
expected to be equally immortal. Does it ever find these favorable
circumstances?
The investigations of microscopists indicate that it does--that
evolution has provided it with these favorable circumstances, in the
bodies of the higher animals. Let us recall in outline the early history
of the fertilized germ-cell, the _zygote_ formed by the union of ovum
and spermatozoon. These two unite to form a single cell, which is
essentially the same, physiologically, as other germ-cells. It divides
in two similar cells; these each divide; the resulting cells again
divide, and so the process continues, until the whole body--a fully
developed man,--has been produced by division and redivision of the one
zygote.
But the germ-cell is obviously different from most of the cells that
make up the finished product, the body. The latter are highly
differentiated and specialized for different functions--blood cells,
nerve cells, bone cells, muscle cells, and so on, each a single cell but
each adapted to do a certain work, for which the original,
undifferentiated germ-cell was wholly unfit. It is evident that
differentiation began to take place at some point in the series of
divisions, that is to say, in the development of the embryo.
Th. Boveri, studying the development of a threadworm, made the
interesting discovery that this differentiation began at the first
division. Of the two daughter-cells produced from the zygote, one
continued dividing at a very slow rate, and without showing any
specialization. Its "line of descent" produced only germ-cells. The
products of division of the other daughter-cell began to differentiate,
and soon formed all the necessary kinds of cells to make up the body of
the mature worm. In this body, the cells from the first daughter-cell
mentioned were inclosed, still undifferentiated: they formed the
germ-cells of the next generation, and after maturity were ready to be
ejected from the body, and to form new threadworms.
Imagine this process taking place through generation after generation of
threadworms, and one will realize that the germ-plasm was passed on
directly from one generation to the next; that in each generation it
gave rise to body-plasm, but that it did not at any time lose its
identity or continuity, a part of the germ-plasm being always set aside,
undifferentiated, to be handed on to the next generation.
In the light of this example, one can better understand the definition
of germ-plasm as "that part of the substance of the parents which does
not die with them, but perpetuates itself in their offspring. " By
bringing his imagination into play, the reader will realize that there
is no limit to the backward continuity of this germ-plasm in the
threadworm. Granted that each species has arisen by evolution from some
other, this germ-cell which is observed in the body of the threadworm,
must be regarded as part of what may well be called a stream of
germ-plasm, that reaches back to the beginning of life in the world. It
will be equally evident that these is no foreordained limit to the
forward extension of the stream. It will continue in some branch, as
long as there are any threadworms or descendants of threadworms in the
world.
The reader may well express doubt as to whether what has been
demonstrated for the threadworm can be demonstrated for the higher
animals, including man. It must be admitted that in many of these
animals conditions are too unfavorable, and the process of embryology
too complicated, or too difficult to observe, to permit as distinct a
demonstration of this continuity of the germ-plasm, wherever it is
sought. But it has been demonstrated in a great many animals; no facts
which impair the theory have been discovered; and biologists therefore
feel perfectly justified in generalizing and declaring the continuity of
germ-plasm to be a law of the world of living things.
Focusing attention on its application to man, one sees that the race
must represent an immense network of lines of descent, running back
through a vast number of different forms of gradually diminishing
specialization, until it comes to a point where all its threads merge in
one knot--the single cell with which it may be supposed that life on
this globe began. Each individual is not only figuratively, but in a
very literal sense, the carrier of the heritage of the whole race--of
the whole past, indeed. Each individual is temporarily the custodian of
part of the "stuff of life"; from an evolutionary point of view, he may
be said to have been brought into existence, primarily to pass this
sacred heritage on to the next generation. From Nature's standpoint, he
is of little use in the world, his existence is scarcely justified,
unless he faithfully discharges this trust, passing on to the future
the "Lamp of Life" whose fire he has been created to guard for a short
while.
Immortality, we may point out in passing, is thus no mere _hope_ to the
parent: it is a _real possibility_. The death of the huge agglomeration
of highly specialized body-cells is a matter of little consequence, if
the germ-plasm, with its power to reproduce not only these body-cells,
but the mental traits--indeed, we may in a sense say the very soul--that
inhabited them, has been passed on. The individual continues to live, in
his offspring, just as the past lives in him. To the eugenist, life
everlasting is something more than a figure of speech or a theological
concept--it is as much a reality as the beat of the heart, the growth of
muscles or the activity of the mind.
This doctrine of the continuity of germ-plasm throws a fresh light on
the nature of human relationships. It is evident that the son who
resembles his father can not accurately be called a "chip off the old
block. " Rather, they are both chips off the same block; and aside from
bringing about the fusion of two distinct strains of germ-plasm, father
and mother are no more responsible for endowing the child with its
characters except in the choice of mate, than is the child for "stamping
his impress" on his parents. From another point of view, it has been
said that father and son ought to be thought of as half-brothers by two
different mothers, each being the product of the same strain of paternal
germ-plasm, but not of the same strain of maternal germ-plasm.
Biologically, the father or mother should not be thought of as the
_producer_ of a child, but as the trustee of a stream of germ-plasm
which produces a child whenever the proper conditions arise. Or as Sir
Michael Foster put it, "The animal body is in reality a vehicle for ova
or sperm; and after the life of the parent has become potentially
renewed in the offspring, the body remains as a cast-off envelope whose
future is but to die. " Finally to quote the metaphor of J. Arthur
Thomson, one may "think for a moment of a baker who has a very precious
kind of leaven; he uses much of this in baking a large loaf; but he so
arranges matters by a clever contrivance that part of the original
leaven is always carried on unaltered, carefully preserved for the next
baking. Nature is the baker, the loaf is the body, the leaven is the
germ-plasm, and each baking is a generation. "
When the respective functions and relative importance, from a genetic
point of view, of germ-plasm and body-plasm are understood, it must be
fairly evident that the natural point of attack for any attempt at race
betterment which aims to be fundamental rather than wholly superficial,
must be the germ-plasm rather than the body-plasm. The failure to hold
this point of view has been responsible for the disappointing results of
much of the sociological theory of the last century, and for the fact
that some of the work now carried on under the name of race betterment
is producing results that are of little or no significance to true race
betterment.
On the other hand, it must be fairly evident, from the pains which
Nature has taken to arrange for the transmission of the germ-plasm from
generation to generation, that she would also protect it from injury
with meticulous care. It seems hardly reasonable to suppose that a
material of this sort should be exposed, in the higher animals at least,
to all the vicissitudes of the environment, and to injury or change from
the chance of outward circumstances.
In spite of these presumptions which the biologist would, to say the
least, consider worthy of careful investigation, the world is full of
well-intentioned people who are anxious to improve the race, and who in
their attempts to do so, wholly ignore the germ-plasm. They see only the
body-plasm. They are devoted to the dogma that if they can change the
body (and what is here said of the body applies equally to the mind) in
the direction they wish, this change will in some unascertainable way be
reproduced in the next generation. They rarely stop to think that man is
an animal, or that the science of biology might conceivably have
something to say about the means by which his species can be improved;
but if they do, they commonly take refuge, deliberately or
unconsciously, in the biology of half a century ago, which still
believed that these changes of the body could be so impressed on the
germ-plasm as to be continued in the following generation.
Such an assumption is made to-day by few who have thoroughly studied the
subject. Even those who still believed in what is conventionally called
"the inheritance of acquired characteristics" would be quick to
repudiate any such application of the doctrine as is commonly made by
most of the philanthropists and social workers who are proceeding
without seeking the light of biology. But the idea that these
modifications are inherited is so widespread among all who have not
studied biology, and is so much a part of the tradition of society, that
the question must be here examined, before we can proceed confidently
with our program of eugenics.
The problem is first to be defined.
It is evident that all characters which make up a man or woman, or any
other organism, must be either germinal or acquired. It is impossible to
conceive of any other category. But it is frequently hard to say in
which class a given character falls. Worse still, many persons do not
even distinguish the two categories accurately--a confusion made easier
by the quibble that _all_ characters must be acquired, since the
organism starts from a single cell, which possesses practically none of
the traits of the adult.
What we mean by an inborn character is one whose expression is due to
something which is present in the germ-plasm; one which is inherent and
due to heredity. An acquired character is simply a modification, due to
some cause external to the germ-plasm acting on an inborn character. In
looking at an individual, one can not always say with certainty which
characters are which; but with a little trouble, one can usually reach a
reliable decision. It is possible to measure the variation in a given
character in a group of parents and their children, in a number of
different environments; if the degree of resemblance between parent and
offspring is about the same in each case, regardless of the different
surroundings in which the children may have been brought up, the
character may properly be called germinal. This is the biometric method
of investigation. In practice, one can often reach a decision by much
simpler means: if the character is one that appears at birth, e. g. ,
skin color, it is usually safe to assume that it is a germinal
character, unless there is some evident reason for deciding otherwise,
as in the case of a child born with some disease from which the mother
had been suffering for the previous few months. In general, it is more
difficult to decide whether a mental trait is germinal, than whether a
physical one is; and great care should be used in classification.
To make the distinction, one ought to be familiar with an individual
from birth, and to have some knowledge of the conditions to which he was
exposed, in the period between conception and birth,--for of course a
modification which takes place during that time is as truly an acquired
character as one that takes place after parturition. Blindness, for
example, may be an inborn defect. The child from conception may have
lacked the requisites for the development of sight. On the other hand,
it may be an acquired character, due to an ill-advised display of
patriotism on July 4, at some time during childhood; or even to
infection at the moment of birth. Similarly small size may be an inborn
character, due to a small-sized ancestry; but if the child comes of a
normal ancestry and is stunted merely because of lack of proper care and
food, the smallness is an acquired character. Deafness may be congenital
and inborn, or it may be acquired as the result, say, of scarlet fever
during childhood.
Now the inborn characters (excepting modifications _in utero_) are
admittedly heritable, for inborn characters must exist potentially in
the germ-plasm. The belief that acquired characters are also inherited,
therefore, involves belief that in some way the trait acquired by the
parent is incorporated in the germ-plasm of the parent, to be handed on
to the child and reappear in the course of the child's development. The
impress on the parental _body_ must in some way be transferred to the
parental _germ-plasm_; and not as a general influence, but as a specific
one which can be reproduced by the germ-plasm.
This idea was held almost without question by the biologists of the
past, from Aristotle on. Questionings indeed arose from time to time,
but they were vague and carried no weight, until a generation ago
several able men elaborated them. For many years, it was the question of
chief dispute in the study of heredity. The last word has not yet been
said on it. It has theoretical bearings of immense importance; for our
conception of the process of evolution will be shaped according to the
belief that acquired characters are or are not inherited. Herbert
Spencer went so far as to say, "Close contemplation of the facts
impresses me more strongly than ever with two alternatives--either that
there has been inheritance of acquired characters, or there has been no
evolution. " But its practical bearings are no less momentous. Again to
quote Spencer: "Considering the width and depth of the effects which the
acceptance or non-acceptance of one or the other of these hypotheses
must have on our views of life, the question, Which of them is true?
demands beyond all other questions whatever the attention of scientific
men. A grave responsibility rests on biologists in respect of the
general question, since wrong answers lead, among other effects, to
wrong belief about social affairs and to disastrous social actions. "
Biologists certainly have not shirked this "grave responsibility" during
the last 30 years, and they have, in our opinion, satisfactorily
answered the general question. The answer they give is not the answer
Herbert Spencer gave.
But the popular mind frequently lags a generation behind, in its grasp
of the work of science, and it must be said that in this case the
popular mind is still largely under the influence of Herbert Spencer and
his school. _Whether they know it or not_, most people who have not made
a particular study of the question still tacitly assume that the
acquirements of one generation form part of the inborn heritage of the
next, and the present social and educational systems are founded in
large part on this false foundation. Most philanthropy starts out
unquestioningly with the assumption that by modifying the individual for
the better, it will thereby improve the germinal quality of the race.
Even a self-styled eugenist asks, "Can prospective parents who have
thoroughly and systematically disciplined themselves, physically,
mentally and morally, transmit to their offspring the traits or
tendencies which they have developed? " and answers the question with the
astounding statement, "It seems reasonable to suppose that they have
this power, it being simply a phase of heredity, the tendency of like to
beget like.
"
The right understanding of this famous problem is therefore fraught with
the most important consequences to eugenics. The huge mass of
experimental evidence that has been accumulated during the last quarter
of a century has, necessarily, been almost wholly based on work with
plants and lower animals. Even though we can not attempt to present a
general review of this evidence, for which the reader must consult one
of the standard works on biology or genetics, we shall point out some of
the considerations underlying the problem and its solution.
In the first place, it must be definitely understood that we are dealing
only with specific, as distinguished from general, transmission. As the
germ-cells derive their nourishment from the body, it is obvious that
any cause profoundly affecting the latter might in that way exercise an
influence on the germ-cells; that if the parent was starved, the
germ-cells might be ill-nourished and the resulting offspring might be
weak and puny. There is experimental evidence that this is the case; but
that is not the inheritance of an acquired character. If, however, a
white man tanned by long exposure to the tropical sun should have
children who were brunettes, when the family stock was all blond; or if
men whose legs were deformed through falls in childhood should have
children whose legs, at birth, appeared deformed in the same manner;
then there would be a distinct case of the transmission of an acquired
characteristic. "The precise question," as Professor Thomson words it,
"is this: Can a structural change in the body, induced by some change in
use or disuse, or by a change in surrounding influence, affect the
germ-cells in such a _specific_ or representative way that the offspring
will through its inheritance exhibit, even in a slight degree, the
modification which the parent acquired? " He then lists a number of
current misunderstandings, which are so widespread that they deserve to
be considered here.
(1) It is frequently argued (as Herbert Spencer himself suggested) that
unless modifications are inherited, there could be no such thing as
evolution. Such pessimism is unwarranted. There _is_ abundant
explanation of evolution, in the abundant supply of germinal variations
which every individual presents.
(2) It is common to advance an _interpretation_ of some observation, in
support of the Lamarckian doctrine, as if it were a _fact_.
Interpretations are not facts. What is wanted are the facts; each
student has a right to interpret them as he sees fit, but not to
represent his interpretation as a fact. It is easy to find structural
features in Nature which _may be interpreted_ as resulting from the
inheritance of acquired characters; but this is not the same as to say
and to prove that they _have resulted_ from such inheritance.
(3) It is common to beg the question by pointing to the transmission of
some character that is not proved to be a modification. Herbert Spencer
cited the prevalence of short-sightedness among the "notoriously
studious" Germans as a defect due to the inheritance of an acquired
character. But he offered no evidence that this is an acquirement rather
than a germinal character. As a fact, there is reason to believe that
weakness of the eyes is one of the characteristics of that race, and
existed long before the Germans ever became studious--even at a time
when most of them could neither read nor write.
(4) The reappearance of a modification may be mistaken for the
transmission of a modification. Thus a blond European family moves to
the tropics, and the parents become tanned. The children who grow up
under the tropical sun are tanned from infancy; and after the
grandchildren or great-grandchildren appear, brown from childhood, some
one points to the case as an instance of permanent modification of
skin-color. But of course the children at the time of birth are as white
as their distant cousins in Europe, and if taken back to the North to be
brought up, would be no darker than their kinsmen who had never been in
the tropics. Such "evidence" has often been brought forward by careless
observers, but can deceive no one who inquires carefully into the facts.
(5) In the case of diseases, re-infection is often mistaken for
transmission. The father had pneumonia; the son later developed it;
ergo, he must have inherited it. What evidence is there that the son in
this case did not get it from an entirely different source? Medical
literature is heavily burdened with such spurious evidence.
(6) Changes in the germ-cells _along with_ changes in the body are not
relevant to this discussion. The mother's body, for example, is poisoned
with alcohol, which is present in large quantities in the blood and
therefore might affect the germ-cells directly. If the children
subsequently born are consistently defective it is not an inheritance of
a body character but the result of a direct modification of the
germ-plasm. The inheritance of an acquired modification of the body can
only be proved if some particular change made in the parent is inherited
as such by the child.
(7) There is often a failure to distinguish between the possible
inheritance of a particular modification, and the possible inheritance
of indirect results of that modification, or of changes correlated with
it. This is a nice but crucial point on which most popular writers are
confused. Let us examine it through a hypothetical case. A woman, not
herself strong, bears a child that is weak. The woman then goes in for
athletics, in order better to fit herself for motherhood; she
specializes on tennis. After a few years she bears another child, which
is much stronger and better developed than the first. "Look," some one
will say, "how the mother has transmitted her acquirement to her
offspring. " We grant that her improved general health will probably
result in a child that is better nourished than the first; but that is a
very different thing from heredity. If, however, the mother had played
tennis until her right arm was over-developed, and her spine bent; if
these characteristics were nowhere present in the ancestry and not seen
in the first child; but if the second child were born with a bent spine
and a right arm of exaggerated musculature, we would be willing to
consider the case on the basis of the inheritance of an acquired
character. We are not likely to have such a case presented to us.
To put the matter more generally, it is not enough to show that _some_
modification in the parent results in _some_ modification in the child.
For the purposes of this argument there must be a similar modification.
(8) Finally, data are frequently presented, which cover only two
generations--parent and child. Indeed, almost all the data alleged to
show the inheritance of acquired characteristics are of this kind. They
are of little or no value as evidence. Cases covering a number of
generations, where a _cumulative_ change was visible, would be of
weight, but on the rare occasions when they are forthcoming, they can be
explained in some other way more satisfactorily than by an appeal to the
theory of Lamarck. [13]
If the evidence currently offered to support a belief in the inheritance
of acquired characters is tested by the application of these
"misunderstandings," it will at once be found that most of it
disappears; that it can be thrown out of court without further
formality. The Lamarckian doctrine is now held mainly by persons who
have either lacked training in the evaluation of evidence, or have never
examined critically the assumptions on which they proceed. Medical men
and breeders of plants or animals are to a large extent believers in
Lamarckism, but the evidence (if any) on which they rely is always
susceptible of explanation in a more reasonable way. It must not be
forgotten that some of the ablest intellects in the world have been
assidously engaged in getting at the truth in the case, during the last
half-century; and it is certainly worthy of consideration that not in a
single case has the transmission of an acquired body character ever
been proved beyond dispute. Those who still hold a belief in it (and it
is fair to say that some men of real ability are among that number) too
often do so, it is to be feared, because it is necessary for the support
of some theoretical doctrine which they have formulated. Certainly there
are few men who can say that they have carefully examined the evidence
in the case, and accept Lamarckism because the evidence forces them to
do so. It will be interesting to review the various classes of alleged
evidence, though we can cite only a few cases from the great number
available (most of them, however, dealing with plants or lower animals).
Nearly all the evidence adduced can be put in one of these four classes:
(1) Mutilations.
(2) Diseases.
(3) Results of use or disuse.
(4) Physico-chemical effects of environment.
The case in regard to mutilations is particularly clear cut and leaves
little room for doubt. The noses and ears of oriental women have been
pierced for generations without number, yet girls are still born with
these parts entire. Circumcision offers another test case. The evidence
of laboratory experiments (amputation of tails) shows no inheritance. It
may be said without hesitation that mutilations are not heritable, no
matter how many generations undergo them.
(2) The transmissibility of acquired diseases is a question involved in
more of a haze of ignorance and loose thinking. It is particularly
frequent to see cases of uterine infection offered as cases of the
inheritance of acquired characters. To use the word "heredity" in such a
case is unjustified. Uterine infection has no bearing whatever on the
question.
Taking an historical view, it seems fairly evident that if diseases were
really inherited, the race would have been extinct long ago. Of course
there are constitutional defects or abnormalities that are in the
germ-plasm and are heritable: such is the peculiar inability of the
blood to coagulate, which marks "bleeders" (sufferers from hemophilia, a
highly hereditary disease). And in many cases it is difficult to
distinguish between a real germinal condition of this sort, and an
acquired disease.
The inheritance of an acquired disease is not only inconceivable, in the
light of what is known about the germ-plasm, but there is no evidence to
support it. While there is most decidedly such a thing as the
inheritance of a tendency to or lack of resistance to a disease, it is
not the result of incidence of the disease on the parent. It is possible
to inherit a tendency to headaches or to chronic alcoholism; and it is
possible to inherit a lack of resistance to common diseases such as
malaria, small-pox or measles; but actually to inherit a zymotic disease
as an inherent genetic trait, is impossible,--is, in fact, a
contradiction of terms.
(3) When we come to the effects of use and disuse, we reach a much
debated ground, and one complicated by the injection of a great deal of
biological theorizing, as well as the presence of the usual large amount
of faulty observation and inference.
It will be admitted by every one that a part of the body which is much
used tends to increase in size, or strength, and similarly that a part
which is not used tends to atrophy. It is further found that such
changes are progressive in the race, in many cases. Man's brain has
steadily increased in size, as he used it more and more; on the other
hand, his canine teeth have grown smaller. Can this be regarded as the
inheritance of a long continued process of use and disuse? Such a view
is often taken, but the Lamarckian doctrine seems to us just as mystical
here as anywhere else, and no more necessary. Progressive changes can be
satisfactorily accounted for by natural selection; retrogressive changes
are susceptible of explanation along similar lines. When an organ is no
longer necessary, as the hind legs of a whale, for instance, natural
selection no longer keeps it at the point of perfection. Variation,
however, continues to occur in it. Since the organ is now useless,
natural selection will no longer restrain variation in such an organ,
and degeneracy will naturally follow, for of all the variations that
occur in the organ, those tending to loss are more numerous than those
tending to addition. If the embryonic development of a whale's hind leg
be compared to some complicated mechanical process, such as the
manufacture of a typewriter, it will be easier to realize that a trivial
variation which affected one of the first stages of the process would
alter all succeeding stages and ruin the final perfection of the
machine. It appears, then, that progressive degeneration of an organ can
be adequately explained by variation with the removal of natural
selection, and that it is not necessary or desirable to appeal to any
Lamarckian factor of an unexplainable and undemonstrable nature.
The situation remains the same, when purely mental processes, such as
instincts, are considered. Habit often repeated becomes instinctive, it
is said; and then the instinct thus formed by the individual is passed
on to his descendants and becomes in the end a racial instinct. Most
psychologists have now abandoned this view, which receives no support
from investigation. Such prevalence as it still retains seems to be
largely due to a confusion of thought brought about by the use of the
word "instinctive" in two different senses,--first literally and then
figuratively.
A persistent attempt has been made in America during recent years, by
C. L. Redfield, a Chicago engineer, to rehabilitate the theory of the
inheritance of the effects of use and disuse. He has presented it in a
way that, to one ignorant of biology, appears very exact and plausible;
but his evidence is defective and his interpretation of his evidence
fallacious. Because of the widespread publicity, Mr. Redfield's work has
received, we discuss it further in Appendix B.
Since the importance of hormones (internal secretions) in the body
became known, it has often been suggested that their action may furnish
the clue to some sort of an inheritance of modifications. The hormone
might conceivably modify the germ-plasm but if so, it would more likely
be in some wholly different way.
In general, we may confidently say that there is neither theoretical
necessity nor adequate experimental proof for belief that the results of
use and disuse are inherited.
(4) When we come to consider whether the effects of the environment are
inherited, we attack a stronghold of sociologists and historians.
Herbert Spencer thought one of the strongest pieces of evidence in this
category was to be found in the assimilation of foreigners in the United
States. "The descendants of the immigrant Irish," he pointed out, "lose
their Celtic aspect and become Americanised. . . . To say that 'spontaneous
variation,' increased by natural selection, can have produced this
effect, is going too far. " Unfortunately for Mr. Spencer, he was basing
his conclusions on guesswork. It is only within the last few months that
the first trustworthy evidence on the point has appeared, in the careful
measurements of Hrdlicka who has demonstrated that Spencer was quite
wrong in his statement. As a fact, the original traits persist with
almost incredible fidelity. (Appendix C. )
In 1911, Franz Boas of Columbia University published measurements of the
head form of children of immigrants[14] which purported to show that
American conditions caused in some mysterious manner a change in the
shape of the head. This conclusion in itself would have been striking
enough, but was made more startling when he announced that the change
worked both ways: "The East European Hebrew, who has a very round head,
becomes more long-headed; the south Italian, who in Italy has an
exceedingly long head, becomes more short-headed"; and moreover this
potent influence was alleged to be a subtle one "which does not affect
the young child born abroad and growing up in American environment, but
which makes itself felt among the children born in America, even a short
time after the arrival of the parents in this country. " Boas' work was
naturally pleasing to sociologists who believe in the reality of the
"melting-pot," and has obtained widespread acceptance in popular
literature. It has obtained little acceptance among his
fellow-anthropologists, some of whom allege that it is unsound because
of the faulty methods by which the measurements were made and the
incorrect standards used for comparison.
The many instances quoted by historians, where races have changed after
immigration, are to be explained in most cases by natural selection
under new conditions, or by interbreeding with the natives, and not as
the direct result of climate. Ellsworth Huntington, the most recent and
careful student of the effect of climate on man,[15] finds that climate
has a great deal of influence on man's energy, but as far as inherited
traits in general are concerned, he is constantly led to remark how
little heredity is capable of being changed.
Most members of the white race have little toes that are partly
atrophied, and considerably deformed. In many cases one of the joints
has undergone ankylosis--that is, the bones have coalesced. It is
confidently alleged that this is due to the inheritance of the effects
of wearing tight shoes through many centuries. When it is found that the
prehistoric Egyptians, who knew not tight shoes, suffered from the same
defect in a similar degree, one's confidence in this kind of evidence is
much diminished.
The retrogression of the little toe in man is probably to be explained
like the degeneration of the hind leg of the whale, as a result of the
excess of deteriorating variations which, when not eliminated by natural
selection, lead to atrophy. Since man began to limit the use of his feet
to walking on the ground, the little toe has had much less value to him.
The feet of Chinese women offer another illustration along this line.
Although they have been tightly bound for many generations, no deformity
is apparent in the feet of girl babies.
Breeders are generally of the opinion that good care and feed bestowed
on their stock produce results in succeeding generations. This is in a
way true, but it is due merely to the fact that the offspring get better
nourishment and therefore a better start in life. The changes in breeds,
the increase in milk yield, and similar facts, often explained as due to
inheritance of acquired characters, are better explained as the results
of selection, sometimes conscious, sometimes quite unconscious.
[Illustration: BOUND FOOT OF A CHINESE WOMAN
FIG. 5. --For centuries the feet of upper class women, and many
lower class women, in China have been distorted in this manner; but
their daughters have perfect feet when born. ]
[Illustration: DEFECTIVE LITTLE TOE OF A PREHISTORIC EGYPTIAN
FIG. 6. --The above illustration shows the foot of a prehistoric
Egyptian who is estimated to have lived about 8000 B. C. The last joint
of the little toe had entirely disappeared, and careful dissection
leaves no doubt that it was a germinal abnormality, such as is
occasionally seen to-day, and not the result of disease. It is,
therefore, evident that the degeneration of man's little toe must be
ascribed to some more natural cause than the wearing of shoes for many
generations. Photograph from Dr. Gorgy Sobhy, School of Medicine,
Cairo. ]
The question of inherited immunity to diseases, as the result of
vaccination or actual illness from them, has appeared in the controversy
in a number of forms, and is a point of much importance. It is not yet
clear, partly because the doctors disagree as to what immunity is. But
there is no adequate evidence that an immunity to anything can be
created and transmitted through the germ-plasm to succeeding
generations.
In short, no matter what evidence we examine, we must conclude that
inheritance of acquired bodily characters is not a subject that need be
reckoned with, in applied eugenics.
On the other hand, there is a possible indirect influence of
modifications, which may have real importance in man. If the individual
is modified in a certain way, in a number of generations, even though
such a modification is not transmitted to his descendants, yet its
continued existence may make possible, the survival of some germinal
variation bearing in the same direction, which without the protecting
influence of the pre-existing modification, would have been swamped or
destroyed.
Finally, it should be borne in mind that even if physical and mental
characters acquired during a man's lifetime are not transmitted, yet
there is a sort of transmission of acquired characters which has been of
immense importance to the evolution of the race. This is the so-called
"inheritance" of the environment; the passing on from one generation to
the next of the achievements of the race, its accumulated social
experience; its civilization, in short. It is doubtful whether any
useful end is gained by speaking of this continuance of the environment
as "heredity;" it certainly tends to confuse many people who are not
used to thinking in biological terms. Tradition is the preferable term.
There is much to be said in favor of E. B. Poulton's
definition,--"Civilization in general is the sum of those contrivances
which enable human beings to advance independently of heredity. "
Whatever wisdom, material gain, or language is acquired by one
generation may be passed on to the next. As far as the environment is
concerned, one generation stands on the shoulders of its predecessor.
It might simplify the task of eugenics if the same could be said of
biological heredity. But it can not. Each generation must "start from
scratch. "
In August Weismann's words, the development of a function in offspring
begins at the point where it _began_ in his parents, not at the point
where it _ended_ in them. Biological improvement of the race (and such
improvement greatly fosters all other kinds) must be made through a
selective birth-rate. There is no short-cut by way of euthenics, merely.
We must now consider whether there is any direct way of impairing good
heredity. It is currently believed that there are certain substances,
popularly known as "racial-poisons," which are capable of affecting the
germ-plasm adversely and permanently in spite of its isolation and
protection. For example, the literature of alcoholism, and much of the
literature of eugenics, abounds with statements to the effect that
alcohol _originates_ degeneracy in the human race.
The proof or disproof of this proposition must depend in the last
analysis on direct observation and carefully controlled experiments. As
the latter cannot be made feasibly on man, a number of students have
taken up the problem by using small animals which are easily handled in
laboratories. Many of these experiments are so imperfect in method that,
when carefully examined, they are found to possess little or no value as
evidence on the point here discussed.
Hodge, Mairet and Combemale, for example, have published data which
convinced them that the germ-plasm of dogs was injured by the
administration of alcohol. The test was the quality of offspring
directly produced by the intoxicated animals under experiment. But the
number of dogs used was too small to be conclusive, and there was no
"control": hence these experiments carry little weight.
Ovize, Fere and Stockard have shown that the effect of alcohol on hen's
eggs is to produce malformed embryos. This, however, is a case of
influencing the development of the individual, rather than the
germ-plasm. Evidence is abundant that individual development can be
harmed by alcohol, but the experiments with eggs are not to the point
of our present purpose.
Carlo Todde and others have carried out similar experiments on cocks.
The conclusions have in general been in favor of injury to the
germ-plasm, but the experiments were inadequate in extent.
Laitinen experimented on rabbits and guinea pigs, but he used small
doses and secured only negative results.
Several series of experiments with rats indicate that if the dosage is
large enough, the offspring can be affected.
Nice, using very small numbers of white mice, subjected them not only to
alcohol, but to caffein, nicotin, and tobacco smoke. The fecundity of
all these sets of mice was higher than that of the untreated ones used
as control; all of them gained in weight; of 707 young, none was
deformed, none stillborn, and there was only one abortion. The young of
the alcoholized mice surpassed all others in growth. The dosage Nice
employed was too small, however, to give his experiment great weight.
At the University of Wisconsin, Leon J. Cole has been treating male
rabbits with alcohol and reports that "what appear to be decisive
results have already been obtained. In the case of alcoholic poisoning
of the male the most marked result has been a lessening of his
efficiency as a sire, the alcohol apparently having had some effect on
the vitality of his spermatozoa. " His experiment is properly planned and
carried out, but so far as results have been made public, they do not
appear to afford conclusive evidence that alcohol originates degeneracy
in offspring.
The long-continued and carefully conducted experiment of Charles R.
Stockard at the Cornell Medical College is most widely quoted in this
connection. He works with guinea-pigs. The animals are intoxicated
daily, six days in the week, by inhaling the fumes of alcohol to the
point where they show evident signs of its influence; their condition
may thus be compared to that of the toper who never gets "dead drunk"
but is never entirely sober. Treatment of this sort for a period as long
as three years produces no apparent bad effect on the individuals; they
continue to grow and become fat and vigorous, taking plenty of food and
behaving in a normal manner in every particular. Some of them have been
killed from time to time, and all the tissues, including the
reproductive glands, have been found perfectly normal. "The treated
animals are, therefore, little changed or injured so far as their
behavior and structure goes. Nevertheless, the effects of the treatment
are most decidedly indicated by the type of offspring to which they give
rise, whether they are mated together or with normal individuals. "
Before the treatment is begun, every individual is mated at least once,
to demonstrate its possibility of giving rise to sound offspring. The
crucial test of the influence of alcohol on the germ-cells is, of
course, the mating of a previously alcoholized male with a normal,
untreated female, in a normal environment.
When the experiment was last reported,[16] it had covered five years and
four generations. The records of 682 offspring produced by 571 matings
were tabulated, 164 matings of alcoholized animals, in which either the
father, mother, or both were alcoholic, gave 64, or almost 40%, negative
results or early abortions, while only 25% of the control matings failed
to give full-term litters. Of the 100 full-term litters from alcoholic
parents 18% contained stillborn young and only 50% of all the matings
resulted in living litters, while 47% of the individuals in the litters
of living young died soon after birth. In contrast to this record 73% of
the 90 control matings gave living litters and 84% of the young in these
litters survived as normal, healthy animals.
"The mating records of the descendants of the alcoholized guinea pigs,
although they themselves were not treated with alcohol, compare in some
respects even more unfavorably with the control records than do the
above data from the directly alcoholized animals. " The records of the
matings in the second filial generation "are still worse, higher
mortality and more pronounced deformities, while the few individuals
which have survived are generally weak and in many instances appear to
be quite sterile even though paired with vigorous, prolific, normal
mates.
