suggest one further caution which must be borne in mind. There may at
times seem to be suggestions of antagonism between the biological and
the social conceptions of what is eugenic and what is not. Much of
this apparent discord will disappear if we recognize that after all
the overlapping areas of the two subjects which have fused into the
subject of Eugenics are relatively small portions of either whole
subject. Sociology has for one of its aims, perhaps its chief aim, the
improvement of the present condition of society. The sociologist is
interested in the improvement of social conditions to-day and
to-morrow. He wants to improve housing conditions, food and milk
supplies, to reduce the curses of alcoholism, poverty, and crime, to
take the children out of the factory and their mothers out of the
sweatshop and put them into schools or under humane conditions of
labor. And so on through a long list. The biologist or Eugenist is of
course heartily with the sociologist in these endeavors, but as a
human being, not as a biologist or Eugenist. For the Eugenist is, as
such, by deliberate assumption and definition, directly interested in
only such conditions as affect the innate characteristics of the
race, conditions which may not have direct reference to the present
generation at all, but to the next and to future generations. As a
Eugenist he is not concerned with factory legislation, alcoholism, or
play grounds, unless it can be shown that there is a relation between
these things and the innate mental and physical properties of the
race. If there is such a relation, of improvement or impairment, these
are eugenic topics; if there is no such relation they are purely
social topics, and the Eugenist does not deal with them, not because
they are not worth dealing with, but because they are then by
definition outside his field. In the end the Eugenist hopes, with the
Sociologist, to accomplish these social betterments, but he believes
that these will come as by-products in the process of innate racial
improvement--improvement in the inherent, physical, mental, and moral
qualities of the human kind, and that accomplished in this way the
results will be more stable and permanent than any accomplished by
attacking the problems as such and separately, largely leaving out of
account the real and fundamental cause--bad human protoplasm.
Eugenics is not offered as a universal cure for social ills: no single
cure exists. But the Eugenist believes that no other single factor in
determining social conditions and practices approaches in importance
that of racial structural integrity and sanity. The Eugenist would
oppose only those social activities, if such there be, that conflict
with his ideal of genuine, progressive, human evolution. The main
question which the Eugenist would raise here is largely that of the
economy of effort--whether it were not better by concentrating upon a
few activities, known to give permanent results, once for all to end
an intolerable social condition, rather than to attempt the Sisyphean
task.
In conclusion let us quote a few sentences from Francis Galton.
"Charity refers to the individual; Statesmanship to the nation;
Eugenics cares for both.... I take Eugenics very seriously, feeling
that its principles ought to become one of the dominant motives in a
civilized nation, much as if they were one of its religious tenets....
Man is gifted with pity and other kindly feelings; he has also the
power of preventing many kinds of suffering. I conceive it to fall
well within his province to replace Natural Selection by other
processes that are more merciful and not less effective. This is
precisely the aim of Eugenics. Its first object is to check the birth
rate of the Unfit instead of allowing them to come into being, though
doomed in large numbers to perish prematurely. The second object is
the improvement of the race by furthering the productivity of the Fit,
by early marriages and the healthful rearing of their children.
Natural Selection rests upon excessive production and wholesale
destruction; Eugenics on bringing no more individuals into the world
than can be properly cared for, and those only of the best stock."
II
THE BIOLOGICAL FOUNDATIONS OF EUGENICS
II
THE BIOLOGICAL FOUNDATIONS OF EUGENICS
"The gist of histories and statistics as far back as the
records reach, is in you this hour,..."
We must now proceed to consider briefly and with only the necessary
detail the modes of application of certain biological principles and
data in this special field of Eugenics. First of all a clear
understanding of the basic ideas of variability and heredity must be
had as a primary condition of an appreciation of their significance
for the subject before us.
Like any other organism a human being is a bundle of characteristics,
physical and psychical. Each person has a definite stature and span,
possesses fingers and toes, a head, eyes, ears, hair of a certain
color, and so on through a long list of physical traits. Physiological
characteristics has he also, such as muscular strength, resistance to
fatigue or to disease of many kinds, digestive and assimilative
powers, a rate of heart beat, a blood pressure, an habitual gait,
posture, a characteristic way of clasping the hands or of twirling
the thumbs--and so almost _ad infinitum_. He also possesses
certain physiological traits more closely related with the action
of the central nervous system--keenness of vision, or hearing,
or smell, memory, vivacity, cheerfulness, self-assertiveness,
self-consciousness, reasoning power, determination, and the like.
There is a period during the existence of each human being when he
does not seem to possess these traits or anything resembling them. For
at the beginning of his existence as a new and separate creature,
every individual, among the groups of higher organisms, has the form
of a single organic cell--the germ. This germ may be, as it is in man,
of microscopic dimensions, and it always shows a comparatively slight
degree of differentiation of structure. Moreover, the parts and organs
of the germ bear no actual or visible resemblance at all to the organs
and parts of the organism into which the germ rapidly develops. In
other words, in the germ of an organism we have a structure, partly
material, partly dynamic, the components of which in some way
represent the adult characteristics without resembling them. During
the period of the development of the individual, that is to say,
during its "ontogeny," these characteristics of the germ become
expressed in their final or adult form.
For our purpose it is not necessary to inquire precisely how it is
that the structure of the germ can thus represent or determine the
structures growing out of it. It must suffice to see that somehow the
characteristics of the germ lead to the formation or development of
other characters, and these in turn to still others until at last a
period of comparative changelessness is reached, when we say that
development is completed. It is important to recognize, however, that
this development is fundamentally a process of reaction, the reaction
between the germ and its surrounding conditions. The characteristics
of the adult organism are _determined_ primarily by the structure of
the germ; they _appear_ gradually and successively, as the growing
organism reacts to its environing conditions.
An adult organism is continually doing certain things--performing
certain movements, producing certain secretions, undergoing a great
variety of physical and chemical changes. Just what the organism does
at any given moment is in reality determined by two groups of factors:
first, it depends, obviously, upon the structure of the organism
acting, upon the organs it has to act with, and upon the precise
condition of these organs and of the whole individual; and second, it
depends upon the nature of those conditions outside of and affecting
the organism which lead it to act at all. Either group of factors
taken alone will not lead to any activity; activity of an organism
must be a reaction between organismal structure and environing
conditions--an irritable substance and stimuli to activity. And the
character or quality of an act is affected by circumstances within
either set of factors.
In much the same way the germ acts, and its action is similarly a
reaction between the structure of the germ and its environing
conditions. The germ reacts by producing certain parts,
differentiating certain structures, in short, by developing. The
normal activities or reactions of the adult organism we call in
general its "behavior." The normal activities or reactions of the germ
and embryo we call "development"; the normal behavior of the germ is
development. And in the latter, as well as in the former, changes in
either set of factors lead to changes in the nature of the result of
their interaction, i. e., to changes in the characteristics actually
appearing as the result of development.
In their fully developed state some of the traits or characteristics
of organisms are single, simple, fundamental characters, not
analyzable into more elementary factors. Such are the number of
fingers, or of joints in the fingers, absence of pigments of several
kinds from the eyes or hair, presence of cataract, _et cetera_. These
so-called "unit characters" are roughly analogous to the chemical
elements which may, as units, be combined and recombined in diverse
ways, but which always maintain their integrity as elements although
different combinations produce wholes that are unlike. Each unit
character in the adult is the result of a series of reactions between
the environing conditions of development and a germinal structural
unit, as yet hypothetical and provisionally called the "determiner,"
which in some way not yet understood represents this adult trait.
On the other hand, there are many of these things which we call
characteristics which seem to be composite, capable of being analyzed
or factored into a group of simpler components or unit characters.
Such apparently are stature, span, resistance to fatigue, and probably
most psychic traits. Each of these complexes results apparently from a
series of reactions between the conditions of development and a group
of hypothetical germinal determiners that tend to be associated within
the germ.
The presence or absence of a determiner in a germ is thus the primary
cause of the corresponding presence or absence of a certain
characteristic in the adult organism.
But whatever the essential nature of the characteristic in this
respect, whether simple or complex, we know further that every
organismal characteristic is subject to variation. In any group of
human individuals, for example, we can find persons of different
stature, different weight, with fingers of different length and form,
with heads of different size and shape, hair and eyes of different
shades, different blood pressures, pulse rates, digestive
possibilities, different degrees of determination, cheerfulness,
alertness, and so forth. This fact of variation is not limited to the
comparison of the individuals of a given group or generation among
themselves, but successive generations considered as the units of
comparison show the same sort of thing. And further successive broods
from the same parents exhibit this same phenomenon of variation when
compared with one another. Variation is a universal fact--not only
among organic things but in the inorganic world as well. The variation
which any company of persons shows in stature is paralleled by the
variation in the diameter of the grains in a handful of sand, or of
the drops in a rainstorm.
When we examine the phenomena of variation carefully we find that
they are of two quite distinct categories. The first kind of
variation, that which we most frequently think of as "variation,"
should properly be termed _variability_. Differences of this type are
small _fluctuations_ in any and every character, centering about an
average or mean, which is itself fairly definite and fixed--less
subject to variation in different groups or through successive
generations. For example, if we measure by inches the stature of a
thousand or more persons chosen at random we find that they may vary
from fifty-four to seventy-six inches; the most frequent heights might
be about sixty-nine and sixty-four inches among the men and women
respectively. The results of such a measurement may be expressed
graphically as in Figure 3, which is an expression of the measurement
of 1,052 mothers. The measurement of almost any characteristic in a
large group of any organisms usually gives a result of the kind
figured. The most significant fact here is that this normal
variability exhibited by the traits of living organisms follows
closely the laws of chance or probability. That is to say, the number
of individuals occurring in any class which has a certain deviation
above or below the average, is directly related to, or dependent upon
(in mathematical terms, "is a function of"), the extent of the
deviation of the value of that class from the average of the whole
group. The significance of this is that the precise fluctuation which
we find in any individual is the result of the operation of a large
number of causes or factors, each contributing slightly and variably
to the total result.
[Illustration: FIG. 3.--Recorded measurements of the stature
of 1,052 mothers. The height of each rectangle is
proportional to the number of individuals of each given
height. The curve connecting the tops of the rectangles is
the normal frequency curve. The most frequent height is
between 62 and 63 inches. Average height--62.5 inches.
Standard deviation, 2.39 inches. Coefficient of variability,
3.8 (2.39 = 3.8+ % of 62.5 inches). (From Pearson.)]
Many of the most important facts about variability can be illustrated
by a simple model such as that suggested by Galton. This is a
modification of the familiar bagatelle board, covered with glass and
arranged as shown in Fig. 4. A funnel-shaped container at the top of
the board is filled with peas or similar objects (Fig. 4, _A_). Below
this is a regular series of obstacles symmetrically arranged, and
below these, at the bottom of the board, is a row of vertical
compartments also arranged symmetrically with reference to the chief
axis of the whole system. If we allow the peas to escape from the
bottom of the container and to fall among the obstacles into the
compartments below we find that their distribution there follows
certain laws capable of precise mathematical description, so that it
might be predicted with fair accuracy (Fig. 4, _B_). The middle
compartment will receive the most; the compartments next the middle
somewhat fewer; those farther from the middle still fewer; and the end
compartments fewest. If we connect the top of each column of peas by a
curved line we get just such a curve as that given by the stature
measurements above (Fig. 3), i. e., the normal frequency curve. A
curve of the same essential character would result from plotting the
dimensions of a thousand cobblestones, the deviations from the
bull's-eye in a target-shooting contest, or by plotting the
variability of any organismal character--whether it be the stature or
strength of men, the spread of sparrows' wings, the number of rays on
scallop shells, or of ray-flowers of daisies.
[Illustration: FIG. 4.--Model to illustrate the law of
probability or "chance." Description in the text. _A_, Peas
held in container at top of board. _B_, Peas after having
fallen through the obstructions into the vertical
compartments below. The curve connecting the tops of the
columns of peas is the normal probability curve.]
With this model we may illustrate many other essential facts about
variability which must be borne in mind when approaching the problems
of Eugenics. Before we allow the peas to fall we know quite definitely
what the general distribution of them all will be, but we do not know
at all the future position of any single pea. Of this we can speak
only in terms of probability; the chances are very high that it will
fall in one of the three middle compartments, very low that it will be
in one of the extreme compartments. But the chances are equal,
whatever they are, that it will fall above or below the average or
middle position. We see then that in any group there are many more
individuals near the average, i. e., mediocre, than there are in the
classes removed from the average and the farther the remove of a class
from the average the smaller the number of individuals in that class.
Yet all the individuals belong to the same whole group. This leads to
the very important fact that _an individual may belong to a group
without representing it fairly_. The average individuals are the most
representative. But in order to get a correct idea of the whole group
we must know, first, to what _extent_ deviations occur in each
direction, above and below the group average, and, second, the average
_amount_ by which each individual of the group deviates from this
group average. That is, we must know the amount of variability as well
as the extent of the greatest divergence from the average. The best
measure of the amount of variability exhibited by any group of objects
or organisms is not the simple average or mean of all the individual
deviations from the average of the group; it is the square root of the
mean squared deviations from the group average. This is called the
_index_ of variability or "standard deviation." In order to make
possible the comparison of the variabilities of characteristics
measured in unlike units, such as weight and stature, this index must
be converted into an equivalent abstract quantity. This is done by
reducing the index of variability to per cents of the group average,
giving what is called the _coefficient_ of variability. Thus, for
example, in stature the index of variability (standard deviation) of
certain classes of men is approximately 2.7 inches; that is, in a
large group of men the amount of individual variation from the average
height of 69 inches amounts to 2.7 inches. This gives an abstract
_coefficient_ of about 4.0 per cent, for 2.7 equals 3.9 per cent of
69. Similarly the index of variability of the weight of a group of
university students has been found to be about 16.5 pounds; the
average weight is about 153 pounds, and the coefficient of
variability is therefore about 10.8 per cent (16.5 equals 10.78 per
cent of 153). Although pounds and inches may not be compared, these
two abstract coefficients may be, and we may say that men are more
than twice as variable in weight as in stature.
Turning now to variation of the second type we find what are
ordinarily called _mutations_, or differences quite properly termed
_variations_, in a strict sense, as distinguished from the preceding
fluctuations or variability phenomena. Mutations or variations are
abrupt changes of the average or type condition to a new condition or
value which then becomes a new center of fluctuating variability. The
difference between variability and variation may be illustrated
through an analogy suggested by Galton (Fig. 5). A polygonal plinth,
or better a polyhedron, resting upon one face is easily tipped
slightly back and forth, but after slight disturbance it always
returns to its first position of stable equilibrium. Each face of the
plinth or polyhedron represents an organismal characteristic; these
slight backward and forward movements represent fluctuations, always
centering about the average condition. An unusually hard push sends
the plinth over upon another face in which it has a new position of
stability; this represents true variation or mutation. In this new
position it is again stable, may again be rocked back and forth
showing fluctuations about its new average position.
[Illustration: FIG. 5.--Plinth to illustrate the difference
between variability (fluctuation) and variation (mutation).]
The essential difference between true variation and fluctuation or
variability of an extreme nature, is with reference to the inheritance
of such divergence. In the second generation the offspring of extreme
variates or fluctuations have not the same average as their own
parents but an average much nearer that of the whole group to which
their parents belonged; the average stature of the children of
unusually short or tall parents is respectively greater or less than
that of their own parents--that is, is nearer the average of the whole
group of parents, provided the shortness or tallness of the parents is
a fluctuation. When the shortness or tallness is a true variation or
mutational character, offspring have approximately the same average
stature as their immediate parents, although the children of course
show fluctuation in height so that some are slightly above and others
slightly below the parental height.
Mutations may occur through the addition or the subtraction of single
characters of the simple or unit type. Such are the variations from
brown or blue eyes to albino, five fingers to six, and the like. These
are the familiar "sports" of the horticulturalist and breeder. They
are of the greatest value in evolution, for it seems quite likely that
it is only through the permanent racial fixation of these mutations
that permanent changes in the characters of a breed may be effected,
i. e., evolution occurs primarily through mutation.
In connection with the general subject of variation we should mention
briefly certain aspects of the recent work of Johannsen and Jennings,
showing that many organic specific groups or "species," whose
characters, when measured accurately give what is called a normal
variability curve similar to that of stature illustrated in Fig. 3,
are not really homogeneous groups of fluctuating individuals as the
curves would indicate superficially, but that each gross group or
species is actually composed of a blend of a number of smaller groups,
each with its own average and fluctuating variability. It is only when
these are taken all together as a lump that they fuse into a single
and apparently simple curve.
For example, the curve shown in Fig. 6, A, which is approximately that
of a normal distribution, in some cases might be shown by
experimentation to consist in reality of several truly distinct
elements, say three for purposes of illustration, as shown in Fig. 6,
B. Each of these sub-groups has its own average and its own amount
and extent of variability (fluctuation) and it is only by adding them
together that we get the larger group. Each of these elementary groups
is called a "pure line," which is defined as a group of organisms, all
of which are the progeny of a single individual. The characteristics
of each pure line remain stable through successive generations, each
about its own average; and it is chiefly this fact that enables us to
identify the different lines. Transition from the condition of one
pure line to another occurs only as a mutation. At present the theory
of the pure line is strictly applicable only to organisms reproducing
asexually or to self-fertilizing forms where the group observed is
actually composed of the progeny of a single organism. It is hardly
possible to say as yet whether or not this extremely important theory
is essentially applicable to the human species or any species where
two organisms are involved in the establishment of a race or line, but
there are some indications of a circumstantial nature that it is thus
applicable in its essentials and so modified as to include this fact
of biparental inheritance.
[Illustration: FIG. 6.--Curves illustrating the relation
between the pure line and the species or other large group.
_A_, a "species" curve composed of three pure lines. _B_,
the separate elements of the larger curve each with its own
average and variability.]
With this bare skeleton of the subject of variation before us let us
see how facts of this kind may have any significance for the subject
of Eugenics, any bearing upon the possibility of racial improvement.
When any of the varying human traits, and they all vary, is measured
carefully and the results tabulated we find that they give us a curve
approximating the normal frequency curve, such as we have described
above and illustrated in Fig. 3. The coefficients of variability of a
great many human traits are known and a few representative
coefficients are given in Table I. This type of variability is given
then, by measurements of physical characteristics of all kinds, and,
what is of greater importance, physiological traits, including mental
and moral characteristics, so far as they can be measured by present
methods, vary in just the same way. Annual individual earnings give us
a curve closely similar to that of a normal frequency curve with an
approximate minimum limiting value. Even the tabulation of citizens
according to their social standing or "civic worth" gives the same
sort of thing. This has been brought out nicely in Galton's discussion
of Booth's classification of the population of London.
TABLE I
_Coefficients of Variability of Certain Human Traits_