Why Do Europeans Have So Many Hair and Eye Colors?
Race; Posted on: 2009-04-08 15:54:58 [ Printer friendly / Instant flyer ]
by Peter Frost
Most humans have only one hair color and one eye color.
Europeans are a big exception: their hair is black but also
brown, flaxen, golden, or red; their eyes are brown but also
blue, gray, hazel, or green. This diversity reaches a maximum in
an area centered on the East Baltic and covering northern and
eastern Europe. If we move outward, to the south and east, we see
a rapid return to the human norm: hair becomes uniformly black
and eyes uniformly brown.
Why this color diversity? And why only in
Europe? Some believe it to be a side effect of natural selection
for fairer skin to ensure enough vitamin D at northern latitudes.
Yet skin color is weakly influenced by the different alleles for
hair color or eye color, apart from the ones for red hair or blue
eyes. Some have no effect at all on skin pigmentation (Duffy
et al. 2004; Sturm and Frudakis 2004).
But why do we see more of this color diversity in Europe than
elsewhere? Perhaps because sexual selection was stronger in
ancestral Europeans, particularly during the long period when
they lived from hunting and gathering.
Among contemporary hunter-gatherers, the ratio of single men
to single women is most unequal in "steppe-tundra"
environments where almost all consumable biomass is in the form
of highly mobile and spatially concentrated herbivores such as
caribou, reindeer, or muskox. On the one hand, men die younger
because of the distances they must cover in search of herds, with
no alternate food sources. On the other, men are less polygynous
because they bear almost the full cost of feeding their families
in a habitat that offers women little opportunity for food
gathering. With fewer men altogether and even fewer polygynous
ones, women have to compete for a limited supply of potential
husbands. They are thus under stronger sexual selection.
News Source: globetrotter.net