Tuesday, April 11, 2006

Blonde antipodals   posted by Razib @ 4/11/2006 05:58:00 PM

Since we are talking about blondes I thought I would bring to everyone's attention this thread which has an interesting collection of photos of non-black hair color about Aboriginal Australians and Melanesians. They seem to have scanned up Birdsell's map of blondism frequencies:

Now, a reasonable question to immediately ask is "is this introgression from admixture with Europeans?" I gave some reasons why this is unlikely earlier, but I think we should not rule it out in the case of Melanesians because it is well known that the peoples of the Pacific have had intercourse (so to speak) with European seamen for the past several hundred years. But, there is a reason for believing this is indigenous: the hair color is often the only "evidence" of European ancestry one can find in these individuals. Their skin is very dark, they never have light eyes and their facial features are population-typical. Granted, if you had admixture in the past and subsequent random mating you would expect that within a large enough population fragments of European traits would emerge now and then, but the key is that non-black hair is the only "European trait" in evidence. To me the most important point is that blue eyes don't ever seem to show up even though this trait is more common than blonde hair among Europeans.

So let's assume the veracity of this trait. Some of us, who have read our C.S. Coon aren't surprised by non-black hair among the indigenous peoples of the southwest Pacific, the question is, why do we see this trait only here outside of Europe? I don't know, but one pet idea I have is that during Neolithic revolution in Asia a lot of peculiar human variation was wiped out by the demographic wave of advance of Chinese rice farmers. Only in places like Papua New Guinea, Melanesia and Australia have out-of-the-norm appearances remained.

Now, another final question, why are the Aboriginals so damn dark so far south? Julian O'Dea has pointed out that Tasmania is at the latitude of Corsica, so the southern continent isn't that far south, but, Napoleon was a white man. I proposed at one point that deme-to-deme diffusion of alleles from fair skinned northern Eurasian populations couldn't move past the cordon of tropical southeast Asia, and that Australian Aboriginals did not possess the standing genetic variation from which selection could operate, but they had enough variation to exhibit a hair color range.

Update: Some of you probably want to look at this (click here for larger image)....