290 CHAPTER 12 | Modern Human Diversity: Race and Racism
Culture and Biological Diversity
Although cultural adaptation has reduced the importance
of biological adaptation and physical variation, at the same
time cultural forces impose their own selective pressures.
For example, take the reproductive fitness of individuals
with diabetes—a disease with a known genetic predispo-
sition. In North America and Europe today, where medi-
cation is relatively available, people with diabetes are as
biologically fit as anyone else. However, if people with dia-
betes do not have access to the necessary medication, as
is true in many parts of the world, their biological fitness
is lost and they die out. Because financial status affects
access to medical resources, one’s biological fitness may be
determined by this cultural factor.
Culture can also contribute directly to the develop-
ment of disease. For example, one type of diabetes is very
common among overweight individuals who get little
exercise—a combination that describes 61 percent of peo-
ple in the United States today. As peoples from traditionalcontribute to human variation through its impact on the
process of growth and development (developmental ad-
aptation). For example, some of the physiological mecha-
nisms for withstanding cold or dissipating heat have been
shown to vary depending upon the climate that an indi-
vidual experiences as a child. Individuals who grow up in
very cold climates develop circulatory system modifica-
tions that allow them to remain comfortable at tempera-
tures that people from warmer climates cannot tolerate.
Similarly, hot climate promotes the development of a
higher density of sweat glands, creating a more efficient
system for sweating to keep the body cool.
Cultural processes complicate studies of body build
and climatic adaptation. For example, dietary differ-
ences particularly during childhood will cause variation
in body shape through their effect on the growth pro-
cess. Another complicating factor is clothing. Much of
the way people adapt to cold is cultural rather than bio-
logical. For example, Inuit peoples of Arctic Canada live
where it is very cold much of the year. To cope with this,
they long ago developed efficient clothing to keep the
body warm. Inside their clothing, the Inuit are provided
with what amounts to an artificial tropical environment.
Such cultural adaptations allow humans to inhabit the
entire globe.
Some anthropologists have also suggested that varia-
tion in features such as face and eye shape relate to climate.
For example, biological anthropologist Carleton Coon and
his colleagues once proposed that the “Mongoloid face,”
common in populations native to East and Central Asia,
as well as Arctic North America, exhibits features adapted
to life in very cold environments.^14 The epicanthic eye
fold (which minimizes the eye’s exposure to the cold), a
flat facial profile, and extensive fatty deposits may help to
protect the face against frostbite.
Although experimental studies have failed to sustain
the frostbite hypothesis, it is true that a flat facial profile
generally goes with a round head. A significant percentage
of body heat may be lost from the head. A round head,
having less surface area relative to volume, loses less heat
than a longer, more elliptical head. As one would predict
from this, populations with more elliptical-shaped heads
are generally found in hotter climates; those with rounder-
shaped heads are more common in cold climates. However,
these same features also could be present in populations
due to genetic drift.
(^14) Coon, C. S. (1962). The origins of races. New York: Knopf.
The epicanthic eye fold is common among people of East Asia. While
some anthropologists have suggested that this feature might be an
adaptation to cold, genetic drift could also be responsible for the
frequency of this trait.
© Steve Elmore
epicanthic eye fold A fold of skin at the inner corner of the
eye that covers the true corner of the eye; common in Asiatic
populations.