Saturday, March 04, 2006


Pigmentation loss is of itself maladaptive

J. Richards tells us very punnily that "Peter Frost has written a cool paper on the evolution of blond hair". Cool it may be but plausible it is not -- if I may use a Yiddish grammatical construction.

The theory put forward is that sexual competition was greater among Nordics and this led to a "different" appearance being favoured -- and those "different people hence reproduced more. This rather wacky theory is based on three postulates and as far as I can see, none are well-attested.

1). Nordics were particularly dependant on men for food acquisition.
2). Nordics had particularly high rates of fatality among males.
3). Nordics have always been particularly sexually liberated.

The facts as I know them are that up until the 20th century the Nordics were as sexually jealous and puritanical as anyone; that many populations and probably all primitive ones have had high rates of male fatality; that Nordics were farmers as well as hunters as far back as we know; and women doing farm work is as common as dirt in human populations.

If I am wrong in those common understandings, I would be delighted to see good evidence of it.

I prefer the traditional theory which I will very briefly restate in a moment but let me offer a small anecdote first: I was once at a conference at Oxford when I got talking to a Swedish psychologist. He was a Knight of the Northern Star, in fact, so he was a very eminent Swede (You didn't know Sweden had knighthoods, did you?). I talked to him about the emigration of Swedes out of Sweden and he commented that seeing the place was mostly in the dark for six months of the year he really didn't understand why anybody ever wanted to live there in the first place.

And that fits in with the view that loss of pigmentation (in hair, eyes, skin) is a MALADAPTIVE mutation (or set of mutations). Because of increased visibility, proneness to skin cancer etc, people with that mutation got competed out of living in desirable places and had to go to places that were at once cloudy (so less likely to allow sun-damage to fair skin etc.) and places that nobody else wanted (because of the cruel climate).

But, to survive in such a climate, abilities to think ahead had to be selected for and that gave us the higher IQ of whites. And with that higher IQ they bounced back and in effect conquered the world.

What's wrong with that account?

That the genes involved in pigment loss seem to be various is the only obvious objection but we still know very little about how genes interact so one crucial mutation could well be at the back of it.


I should of course have mentioned that, while fair skin is maladaptive to an outdoor life in most of the world (sunburn, skin cancer, visibility to prey species etc.), it is of course adaptive in cloudy climes -- being better able to use whatever light there is to make the very important vitamin D. As this article notes, even today, darker skinned people living in cooler climates can develop vitamin D deficiency diseases. It might also be argued that a fair skin is good camouflage for hunters in a snowy environment but ANY naked hunters amid snow would be distinctly unlikely!


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