From Scott MacEachern, Bowdoin College
I read with great interest your article on the possible adaptive value of
melanin in protecting against skin diseases
(28 April, p 7).
It is a pity that
the account is spoiled by an evolutionary just-so story tagged onto the end of
the article, in which the researcher speculates about the environmental
conditions in which dark and light skin would have evolved.
Briefly, there is no evidence that either our prehistoric ancestors living in
sub-Arctic conditions, or for that matter more recent Arctic foragers, found
themselves particularly short of food. They seem to have managed quite well.
Similarly, your writer’s account of “warm, damp tropics where food was
abundant” owes more to romantic travel imagery than to any ethnographic or
archaeological information. The last decade has in fact seen an active debate
about whether it is possible for hunter-gatherers to survive in tropical forest
without partnerships with farmers, precisely because of cyclical shortages of
nutrients in such environments.
The greater part of Africa’s land area, in any case, is not tropical forest,
and most of our information on modern human evolution comes from areas that
would have been woodland or grassland during the relevant time periods.
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Brunswick, Maine
