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GENERATION │ AVERAGE
│ NUMBER
───────────────────────────────┼──────────
I │ 2.00
II │ 4.00
III │ 7.75
IV │ 13.88
V │ 23.70
VI │ 40.53
═══════════════════════════════╧══════════
When we compare these conditions in the thickly populated parts of
modern Europe and of America, with their unstable population, with the
conditions among primitive tribes, it becomes at once apparent that the
total number of ancestors of each type in small communities must be much
less than the number of ancestors in the modern states just referred to.
A characteristic example is presented by the Eskimo of Smith Sound in
North Greenland. From all we know, it seems extremely unlikely that this
community ever consisted of more than a few hundred individuals. From
what we know about the history of Eskimo communities, we might much
rather assume that originally it consisted of a very few families only.
The community has been cut off from the outer world for very long
periods; and while there may have been accessions of new individuals
from outside once each century, on the whole it has remained completely
isolated. It is therefore obvious that the ancestry of this group cannot
contain anything like the million of people required by the theory, but
that all the individuals must be interrelated through their remote
ancestry.
Considering, now, the laws of inheritance as outlined before, it would
appear that in a community of this type, the members of which number
little more than two hundred individuals, the ancestor of every single
individual from the eighth generation back must have been the same,
because the eighth generation would require theoretically two hundred
and fifty-six individuals,—a greater number than are actually found in
the community; and the occurrence of any individuals who have not a good
many near and remote ancestors in common with the whole rest of the
community is highly improbable, if not impossible.
It follows from this at once that the variability of the whole series
around its typical average must be rather small, because all the members
of the group will have a certain amount of family resemblance. This
uniformity of type will, of course, be the greater, the more uniform the
ancestral group.
On the other hand, these conditions bring about another peculiar
characteristic of the isolated group. Owing to the constant recurrence
of the same ancestral types among the whole group, the type of the whole
people becomes very similar to the characteristic traits of the small
ancestral group; and the smaller this group, the stronger will be the
probability of the type of the local group being quite distinct from the
type of the whole people to which they belong.
It seems to my mind that these conditions explain to a considerable
extent the occurrence of distinct local types in primitive races. When
we find, for instance, that in North America a very marked type belongs
to the Arctic coast of the continent, that a quite distinct type is
found in the Mackenzie basin, still others in well-defined localities on
the Pacific coast, again others in the Mississippi basin, one in the
southeast, and one along the Rio Grande and in Mexico,—it seems
plausible to ascribe their origin to the increase of small isolated
groups, which, as we have seen, must necessarily lead to differentiation
of type.
This view of the origin of local races is quite in accord with the
remarkable results obtained by Johannsen in his studies of heredity. He
repeated artificially the conditions which prevail in a small community,
and exaggerated them by selecting types of equal form, and by
propagating them by self-fertilization. He raised in this way
bean-plants from beans of equal weight, and was able to restrict
variation of the type, so that practically any kind of bean of
particular weight and particular form could be bred true to the type of
its ancestor, and without perpetuating the accidental variations of the
ancestors. In cases where the ancestry goes back to a limited number of
individuals, as among our isolated tribes, the variation will, of
course, not be restricted to the same extent; but the characteristic
development of a stable type is quite analogous to the experiment made
by Johannsen.
Another phenomenon may be pointed out here which is still little
investigated, but which deserves careful attention. We have seen that in
stable communities in sparsely settled countries the relationship
between members of a tribe will be quite close, and that this
relationship will necessarily affect the type and its variability. In
course of time two areas whose population has thus developed may be
thrown into contact, and numerous intermarriages may occur. It will be
seen at once, that, although the differences between the two types may
be apparently only slight, a complete disturbance in the forms of
heredity will result, because a great number of individuals of distinct
ancestry are thrown together. To give an example. The South Italians and
the Spaniards represent two types not very distinct in physical
features, but separated for centuries. The small village communities of
Italy, as well as those of Spain, have all the characteristics of
communities in which endogamic marriages have been continued for a long
period. In the Argentine Republic these two types come into contact and
intermarry frequently. We have no observations on the result of this
mixture upon physical characteristics, but it has been noted that the
distribution of male and female births is quite different from that
prevailing in families in which both parents are either Spanish or
Italian (Pearl). It is also conceivable that this may be one of the
elements bringing about the change of type of urban populations when
compared to rural populations in Europe, and that it may have been
active in the change of type observed among the descendants of European
immigrants in America; for, although the observations have been made on
pure types, in America cases of intermarriages of natives of different
villages are much more common than in Europe.
After we have thus considered the influences of heredity and
environment, so far as they determine the characteristics of distinct
types of man, it remains to add a few words on the individuals
constituting each type, and on the different distribution of individuals
in distinct types.
I have had to refer repeatedly to the phenomena of variation in the
races of man; and I have pointed out before, that, so far as individual
features are concerned, we find that the range of variations in each
human type is so great, that overlapping of the range of variation in
different types is of constant occurrence. We have seen, for instance,
that the medium brains of the Europeans occur with considerable
frequency among negroes, and that only the excessively small negro
brains have no parallel forms among the Europeans; and correspondingly
that the excessively large European brains have no parallel forms among
the brains of the negroes. The amount of variability in regard to
various physical traits differs very considerably in different races.
Most of the European types, for instance, are remarkable for their high
variability. The same is true of the Polynesians and of some negro
tribes. On the other hand, people like the European Hebrews, and, even
more so, the North American Indians, are characterized by, comparatively
speaking, much greater uniformity. The amount of variability differs
considerably with regard to different physical features. It is, for
instance, obvious that the hair-color and hair-form of North Europeans
is much more variable than the hair-color and hair-form of the Chinese.
In Europe the colors vary from flaxen to black, with a considerable
number of individuals with red hair, and the form varies from straight
to high degrees of waviness. Among the Chinese, on the other hand, we do
not find equal variations in the darkness of color, since blondes and
curly-haired individuals are absent. Similar observations may be made in
regard to stature, head-form, or any other feature of the body that can
be expressed by measurements.
The reason for the differences in variability is partly given in our
previous remarks. We have seen, when a people is descended from a small
uniform group, that then its variability will decrease; while on the
other hand, when a group has a much-varied origin, or when the ancestors
belong to entirely distinct types, the variability may be considerably
increased. In all cases which have been investigated, even in those in
which the variability is small, there still remain considerable
differences in bodily appearance among the individuals constituting a
tribal or national or other social unit; and what is true of the
physical traits is obviously no less true of the mental traits, but it
is difficult to express mental characteristics in numerical terms of
variability. An acquaintance with tribes which are apparently on the
simplest level socially, however, shows the existence of certain
individuals of most diverse types of disposition and intellect; and as
might be expected, if we consider mental condition as dependent upon
bodily form, the great variability, even in the most uniform group, of
the structure of the body, particularly of the brain, makes it plausible
that very large differences in individual disposition may be expected.
What we have said before in regard to the overlapping of variations
among different races and types, and the great range of variability in
each type, may also be expressed by saying that the differences between
different types of man are, on the whole, small as compared to the range
of variation in each type.
The importance of these observations in the domain of mental development
will be the subject of our future discussions.
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Footnote 2:
These generations are not completely known. The values here given are
the maximum values which would be found provided the unknown
individuals had had no “loss of ancestors.”
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