How Europeans evolved to have white skin - or rather how Africans adapted to cold

jeudi 9 avril 2015

I find the idea that Europeans have "white" skin ridiculous. Not even the most pasty-faced English person has white skin. Nor for that matter do people from Africa have "black" skin. I fervently wish we could stop talking about ethnicity in terms of black & white. Particular as this article makes clear that changes in skin colour are merely skin deep and tell us nothing more that when some of us migrated to Europe.



But anyway some interesting science - if you can get past the Independent take on this



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Ancient populations in Spain, Luxembourg and Hungary had dark skin around 8,500 years ago



By comparing key parts of DNA across the genomes of 83 ancient humans from European archaeological sites with recent ones from the 1000 Genomes Project, Iain Matheison of Harvard University’s lab of population, and geneticist David Reich, discovered the genes linked to skin pigmentation that had survived the natural selection process across Europe.



When modern humans first travelled from Africa to the continent around 40,000 years ago they had darker skin, which was still seen in Spain, Luxembourg and Hungary around 8,500 years ago.



These humans lacked two genes – SLC24A5 and SLC45A2 – which lead to the depigmentation and lightening of the skin. But in the far north, ancient bodies in Sweden from 7,700 years ago were found to have both these genes, and a third causing blue eyes, meaning they were pale-skinned and blue-eyed.



Once the first farmers from the near East began to arrive in Europe, and who carried both genes for light skin, they began breeding with the “indigenous hunter gatherers”. One of the depigmentation genes became prominent throughout Europe to the point where central and southern Europeans developed lighter skin.



Europeans have not always been light skinned, and Caucasians are in fact a fairly new development on the continent, relatively speaking.



According to a new study reported in Science Magazine, it has been found that Caucasions (no such thing) are the product of “a patchwork of evolution in different places” across Europe, while scientist have discovered three genes that produce light skin – both of which have played a part in the lightening of Europeans’ skin colour over the past 8,000 years.



Since researchers began to sequence the genome of ancient populations last year, it has been discovered that Europeans today are the product of hunter gatherers and farmers of at least three ancient populations having mixed together during their migration to the continent over the past 8,000 years.




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