TTNZ, cool
While I thought the article was interesting, I don't agree with it's conclusions. Firstly it, http://human-nature.com/nibbs/02/frost.html, starts out with "Long intense sunlight favoured a lush growth of mosses, lichens, grasses, and low shrubs that fed mammoths, reindeer, bison, and horses. Despite this high bioproductivity, the loess-steppe confronted...."

It may be long intense sunlight, but it's a lot less intense than in Africa. That is why depigmentation was highly selected for. Vit.D comes from sunlight (synthesized via), not meat. Sunlight degrades folic acid (or folate) and so pigmentation is highly selected for in the African environs. ...and yes, through the wisdom of intelligent design, the dark skin is just dark enough to protect the folate but still make vit.D in Africa & vice versa for the light skin up North.
Lack of folate causes birth defects. Actually I think light skins need to supplement with folate a bit (leafy greens). Musta been hard in the winter months. Maybe all those hair colors came from the increased birth defects.

...and what's this stuff about white hair??
also...dark skin tans too. I think tanning is not a recent adaptation.
I think we follow the same rules, everything is consistent; although I'm sure cultural and psychological selection pressures have added some new rules.

I'll have to read those articles more thoroughly before I post them next time. I can usually follow technical explanations, but I didn't understand any of that genetic stuff.
Thanks,
~Sam
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Pyrolysis creates reduced carbon! ...Time for the next step in our evolutionary symbiosis with fire.