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Here’s How Europeans Quickly Evolved Lighter Skin

Darker skinned people lived in Europe until fairly recently

(Christophe Courteau/Water Rights/Corbis)
smithsonian.com

As Europeans divided and conquered much of the world, they carried the genes for light skin with them. But even Europeans haven’t been white for very long. New analysis of ancient European genes shows that other traits we associate with modern Europeans, such as tallness and the ability to digest milk, are also relatively recent additions to the continent’s genetic profile.

The new data, presented at the annual meeting of the American Association of Physical Anthropologists, comes from the genomes of 83 people found in archeological sites across Europe, reports Ann Gibbbons for Science

For years, researchers assumed that skin lightened as humans migrated from Africa and the Middle East into Europe, about 40,000 years ago. A sun lower in the sky and shorter day lengths would have favored skin that more easily synthesized vitamin D. But researchers are now learning that other factors must have been at play. 

For example, earlier this year, the genome sequencing of a hunter-gatherer who lived in what is now Spain helped build the case that Europe was home to blue-eyed but dark-skinned people. This man, however, lived just 7,000 years ago. The researchers write that their analysis suggests that light skin was not yet widespread and ubiquitous in Europe at the time. Earlier work done with the genes of the 83 people in the new study, supported by linguistic evidence, also shows that populations in Europe about 8,000 years ago would have been mixed and diverse

The new study adds to this growing pile of evidence. Gibbons reports that the researchers found that Europeans probably couldn’t have digested milk until about 4,300 years ago. And the story of skin pigmentation is complex. She writes:

[T]he new data confirm that about 8500 years ago, early hunter-gatherers in Spain, Luxembourg, and Hungary also had darker skin: They lacked versions of two genes—SLC24A5 and SLC45A2—that lead to depigmentation and, therefore, pale skin in Europeans today.

But in the far north—where low light levels would favor pale skin—the team found a different picture in hunter-gatherers: Seven people from the 7700-year-old Motala archaeological site in southern Sweden had both light skin gene variants, SLC24A5 and SLC45A2. They also had a third gene, HERC2/OCA2, which causes blue eyes and may also contribute to light skin and blond hair. Thus ancient hunter-gatherers of the far north were already pale and blue-eyed, but those of central and southern Europe had darker skin.

“What we thought was a fairly simple picture of the emergence of depigmented skin in Europe is an exciting patchwork of selection as populations disperse into northern latitudes,” paleoanthropologist Nina Jablonski, of Penn State told Science. “This data is fun because it shows how much recent evolution has taken place.”

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