Boas, Franz. Race, Language and Culture – T07

[Race]

The Tempo of Growth of Fraternities 11

I Have shown that when the period of maximum rate of growth is
early, the whole growth proceeds at a rapid rate from early years on,
at least as far as our material permits us to follow it; the onset of the
puberty spurt is early, its intensity great, its duration short. Conversely,
when the period of maximum rate of growth is late its intensity is slight,
its duration long. This is expressed by the values of the maximum rates
of growth which are low for those who reach maturity late, high for
those who reach it early.

It is a most important question to decide whether this unity of the
tempo of development that prevails until maturity has been reached
will extend over later life. As far as I am aware the only reliable material
that shows an interrelation of phenomena of aging and of the life
span is that discovered by Dr. Felix Bernstein, who has proved that
early presbyopia indicates an early death by senile degeneration. All
others are more or less impressions of medical practitioners who believe,
for instance, that early calcification of the larynx indicates an early
onset of arterial degeneration. It seems most important that by organized
effort the life history of individuals should be followed up in order
to show whether the rate at which physiological development and decay
occur are constitutionally determined. Studies on longevity also suggest
that this is the case, but they can never be quite convincing.

The observations here discussed refer to individual development.
We had to investigate next whether the conditions that determine the
speed of the life cycle are hereditary or determined by environment. If
they are hereditary we may expect that members of fraternities are alike
in their tempo, provided the social conditions of the whole community
investigated are fairly uniform. The best material at my disposal is
contained in the records of the Hebrew Orphan Asylum in New York,
for here the conditions of nutrition, shelter and mode of life are as uniform
as can be obtained. I have already shown that there is a
fairly strong positive correlation between the dates of first menstruation
86of sisters. 12 Unfortunately it was not possible to classify the material
relating to growth in the same manner as was done for other series because,
on account of gaps in the series of observations, the moment of
maximum rate of growth cannot be determined for all members of each
family and the material would have been too scanty. On account of
the asymmetries of the increment curve, particularly during adolescence,
I did not use correlations, but classified the material in three groups,
about equal in numbers — children tall, medium and short at a given
age — and compared the curves of growth of their brothers and sisters.

Then it appeared that the brothers and sisters of the tall ones, who
include many of those with rapid tempo of development, will also
have a rapid tempo, an early time for the maximum rate of growth, a
rapid rate and an early termination of growth, while the brothers and
sisters of the short ones, who include many of those with sluggish tempo
of development, have a slow rate of growth of less intensity and longer
duration (Fig. 1). Since the conditions under which these children
live are unusually uniform, we may conclude that proof for the heredity
of the tempo of growth has been given. This agrees with the results
87obtained by Pearl by experimentation with animals and with observations
on plants of short and long vegetative periods. An analogous study
of children in the Horace Mann School gave the same result. In this
case it might be suspected that similar home environment is a contributory
cause to the similarity of the growth curve of members of each
fraternity (Fig. 2).

It is obvious that a phenomenon of such complexity as length of
body and tempo of development must be governed by many hereditary
factors and that we are dealing with a phenomenon of general organization
of the body and that a search for genes would not be advisable. Is
not there some danger anyway, that the number of genes will depend
rather upon the number of investigators than upon their actual
existence?88