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When did North Africans acquire light skin color?
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[QUOTE]Originally posted by Doug M: [QB] [QUOTE]Originally posted by Archeopteryx: [qb] [QUOTE]Originally posted by Doug M: Beyond that, Denisovans arent humans [/QUOTE]Well obviously they were human enough for some of our ancestors to make babies with them. And since they seem to have been able to get fertile offspring it shows that we were very closely related. So in one way we must call them humans, even if somewhat different. In their case we did not know so very much how they looked since we just have a few bones preserved. Hopefully we will find more complete skeletons in the future so we can compare their morphology with what the DNA showed. It seems research about both neanderthals and denisovans have rendered enough interest to motivate a Nobelprize to Svante Pääbo who has sequenced their genomes. Also in Africa it seems that Homo sapiens mixed with one or more kinds of archaic humans, but we know even less about them than what we know of Denisovans since we can not yet tie them to any skeletons or other human remains. [/qb][/QUOTE]Thats fine and dandy but the point still stands Denisovans aren't human and we know how humans got to Asia. And Denisovans are not a key to human migration to or evolution in Asia, which is implied by this statement. Aboriginal Australians and the Aborigines of the Andamans do not have any Denisovan DNA and those two groups are some of representatives of the oldest human populations in Asia. Not to mention the fact that MOST of the mixing between humans and ancient hominids took place in Africa because that is the birthplace of the hominid family tree to begin with. [QUOTE]Originally posted by Archeopteryx: [qb] About light skin in Asia it seems to first have evolved somewhere between 20 000 and 30 000 years ago. Seems that light skin evolved separately in Europeans and Asians since it is partly different genes involved who came under selection. Then it took time before these genes came to dominate in respective area. With better methods of analysing aDNA, and with more samples we will of course get a more detailed knowledge about when and where. That also goes for other physical traits. [/qb][/QUOTE]Using DNA to determine skin color is not an exact science because skin color varies and there is no singe DNA value that is going to tell you the exact skin complexion of a person. There are multiple various DNA codes that relate to skin color and how they combine for a specific tone or complexion is not fixed but varies across populations and individuals. Not to mention, "light skin" is not a single color but a range of complexions just like "dark skin" isn't a single value but a range of values. So like I was saying before, until we get a study showing an exact correlation between skin color genes and specific tones in a living person, it will remain ambiguous at best. Most of the times these kinds of studies using statistical models use reference populations but those populations are not "universal" and cannot provide the kind of accuracy required for ancient populations across the globe. Also the evolution of "lighter skin" in Africa did not start with Eurasians but that doesn't necessarily mean as light as the lightest Europeans. And most people obsessing with light skin in North Africa are specifically focusing on Eurasian arrival into North Africa. [QUOTE] While many have turned to science to falsely support the notion of a biological construct of race, modern research has demonstrated genetics has little to do with it. Now, as Ed Yong at The Atlantic reports, a large-scale study of skin pigmentation demonstrates that humans with both light and dark skin pigmentation have co-existed for hundreds of thousands of years. A long-standing assumption about the evolution skin color was that Homo sapiens started out in Africa with darkly pigmented skin, full of melanin to protect from the intense ultraviolet radiation from the sun. As humans migrated out of Africa, it was believed that mutations led to lighter skin that can supposedly regulate vitamin D production in lower sunlight levels. But the new study, published in the journal Science, shows that the evolution of skin color is much more complex. A team of researchers led by Sarah Tishkoff at the University of Pennsylvania and her postdoctoral fellow Nicholas Crawford measured the skin pigmentation of over 2,000 genetically and ethnically diverse people across Tanzania, Ethiopia and Botswana. They analyzed the genome of nearly 1,600 of those people, which allowed them to identify eight key areas in the DNA associated with skin pigmentation. As Colin Barras at New Scientist reports, each of these sites had genetic variants associated with paler skin and ones associated with darker skin. Seven genetic variants associated with lighter skin developed at least 270,000 years ago and four more than 900,000 years ago. Considering our species, Homo sapiens, did not evolve until around 200,00 to 300,000 years ago, the discovery suggests that the genes responsible for lighter skin tones were present into the genetic material of our hominin ancestors—hundreds of thousands of years before the first humans walked the Earth.[/QUOTE] https://www.smithsonianmag.com/smart-news/genetic-study-shows-skin-color-just-skin-deep-180965261/ [/QB][/QUOTE]
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