Europeans had darker skin and hair 5,000 years ago

Europeans had darker skin, hair and eye pigmentation 5,000 years ago - until natural selection resulted in lighter pigmentation, according to a new study of DNA from ancient skeletons.
Anthropologists at Johannes Gutenberg University Mainz (JGU) in Germany and geneticists at University College London (UCL), worked in collaboration with archaeologists from Berlin and Kiev to analyse ancient DNA from skeletons.
They found that natural selection has had a significant effect on the human genome even in the past 5,000 years, resulting in sustained changes to the appearance of people.
The researchers compared the prehistoric data with that of contemporary Europeans using computer simulations.

Where the genetic changes could not be explained by the randomness of inheritance, researchers inferred that positive selection played a role, ie, that frequency of a certain mutation increased significantly in a given population.
Sandra Wilde of the Palaeogenetics Group at the JGU Institute of Anthropology noticed striking differences in genes associated with hair, skin, and eye pigmentation.

"Prehistoric Europeans in the region we studied would have been consistently darker than their descendants today," said Wilde, first author of the study.
"This is particularly interesting as the darker phenotype seems to have been preferred by evolution over hundreds of thousands of years. All our early ancestors were more darkly pigmented," Wilde said.

However, things must have changed in the last 50,000 years as humans began to migrate to northern latitudes.
"In Europe we find a particularly wide range of genetic variation in terms of pigmentation," said co-author Dr Karola Kirsanow, who is also a member of the Palaeogenetics Group at Mainz University.
"However, we did not expect to find that natural selection had been favouring lighter pigmentation over the past few thousand years," Kirsanow said.
The signals of selection that the researchers identified are comparable to those for malaria resistance and lactase persistence, meaning that they are among the most pronounced that have been discovered to date in the human genome.

The authors see several possible explanations.
"Perhaps the most obvious is that this is the result of adaptation to the reduced level of sunlight in northern latitudes," said Professor Mark Thomas of UCL, corresponding author of the study.
"Most people of the world make most of their vitamin D in their skin as a result UV exposure. But at northern latitudes and with dark skin, this would have been less efficient. If people weren't getting much vitamin D in their diet, then having lighter skin may have been the best option," he said.
"But this vitamin D explanation seems less convincing when it comes to hair and eye colour," Wilde said.

"Instead, it may be that lighter hair and eye colour functioned as a signal indicating group affiliation, which in turn played a role in the selection of a partner," Wilde said.
The study was published in the journal Proceedings of the National Academy of Sciences (PNAS).