Friday, April 20, 2007

Light skin color in Europeans is recent

News Focus
European Skin Turned Pale Only Recently, Gene Suggests

Ann Gibbons

20 April 2007 Vol. 316, p. 364

This is a news feature regarding a recent talk at the AAPA meetings. I don't quite know what to make of it. On the one hand it reminds me of the absence of the lactose tolerance allele 7,000 ya in Europe, but this seems a bit more implausible since it kinda suggests that Europeans developed lighter skin only 6,000 to 12,000 ya, as opposed to when they first entered the area. (possible reasons given below)

First of all, can we spare these cheesy kinds of opening sentences?: "Researchers have disagreed for decades about an issue that is only skin-deep"

The research was conducted by Heather Norton. Some of the interesting parts:

Regarding the fact that this (SLC24A5) is only one of several genes that is responsible for lighter skin:

"She added that other, unknown, genes probably also cause paling in Europeans" ...

"Either way, the implication is that our European ancestors were brown-skinned for tens of thousands of years--a suggestion made 30 years ago by Stanford University geneticist L. Luca Cavalli-Sforza. He argued that the early immigrants to Europe, who were hunter-gatherers, herders, and fishers, survived on ready-made sources of vitamin D in their diet. But when farming spread in the past 6000 years, he argued, Europeans had fewer sources of vitamin D in their food and needed to absorb more sunlight to produce the vitamin in their skin. Cultural factors such as heavier clothing might also have favored increased absorption of sunlight on the few exposed areas of skin, such as hands and faces, says paleoanthropologist Nina Jablonski of PSU in State College."

This is all really cool. I prefer the Cavalli-Sforza hypothesis, however. It would be great to look at some of the other candidate alleles and to look at them in Neanderthals!! ... looking forward to the publication and what SLC24A5 looks like in the Native American sample they looked at.

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