A study of ancient DNA from people who lived in Europe between 1700 and 45,000 years ago suggests that 63 per cent of them had dark skin and 8 per cent had pale skin, with the rest somewhere in between. It was only around 3000 years ago that individuals with intermediate or pale skin started to become a majority.
Until a few years ago, it was assumed that the modern humans who moved into Europe around 45,000 years ago rapidly evolved paler skin to ensure they got enough vitamin D during dark winters. Cells in the skin can make a precursor of vitamin D when exposed to ultraviolet light, but in darker skin, less ultraviolet reaches these cells.
However, this view has changed as it has become possible to sequence DNA from individuals who lived many thousands of years ago and to apply methods developed by forensic scientists to help identify suspects from DNA samples found at crime scenes.
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In 2018, for instance, researchers found that Cheddar Man, an individual who lived in Britain 10,000 years ago, probably had very dark skin and blue-green eyes. Such predictions about individuals have been criticised, though, as the genetics of pigmentation aren鈥檛 fully understood and so we can鈥檛 be certain about the conclusions.
at the University of Ferrara in Italy and his colleagues have now predicted the skin, eye and hair colour of almost all the ancient Europeans whose genomes have been sequenced so far 鈥� 348 individuals in total 鈥� to get the most comprehensive picture yet of how these traits changed due to factors such as natural selection, sexual selection, war and migration. Gaps in the sequences meant it wasn鈥檛 possible to predict all three traits in all 348 genomes.
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With this large data set, errors should average out at the group level, so the team's overall conclusion that most ancient Europeans were dark-skinned is more robust than the individual predictions. However, the results should still be treated with caution, as there is no way to check whether predictions based on modern European populations are accurate for ancient people.
鈥淭his paper is enormously significant because of the breadth of sampling undertaken and the care and attention given to the analysis of the ancient DNA data,鈥� says at Pennsylvania State University.
The reason why Europeans seem to have evolved paler skin relatively recently may relate to dietary changes as people started living in bigger settlements, says Jablonski. 鈥淢ost Palaeolithic hunter-gatherers and most Bronze Age peoples probably did get sufficient vitamin D from dietary sources, including from the meat of wild animals,鈥� she says. 鈥淭his situation doesn't begin to change significantly until settlements get larger.鈥�
It is possible that some of the Neanderthal peoples who lived in Europe long before modern humans arrived had pale skin, but there was probably a lot of variation, says Jablonski. 鈥淭heir skin colours probably varied nearly as much in time and space as those of modern humans.鈥�
Neanderthals and modern humans did interbreed, but that may have happened outside Europe. Previous studies concluded that pale skin wasn't a trait acquired from the Neanderthals.
Besides the genetic evidence for past skin colour, there are also clues in artworks from early historical times. But artworks cannot be relied on, says Barbujani. For instance, ancient Egyptian artworks always depict women as having lighter skin than men. 鈥淭here's a problem with artistic images of style,鈥� he says.
bioRxiv
