Pale complexions may have evolved many times over.Digital Vision
An analysis of 50,000-year-old Neanderthal DNA suggests that at least some of the ancient hominids probably had pale skin and red hair.
The findings, published this week in Science1, are based on the sequence of a single gene, called mc1r. Humans with a less functional form of the MC1R protein are more likely to be fair skinned — an adaptation that may have helped inhabitants of high latitudes synthesize vitamin D more efficiently in limited sunlight.
Analyses of Neanderthal DNA are always subject to the problem of fossil samples being contaminated with modern human DNA in the lab or the field. But Carles Lalueza-Fox of the University of Barcelona, Spain, with Holger Römpler of the University of Leipzig in Germany and colleagues, found that the mc1r gene in two European Neanderthal fossils they studied contained a single base-pair change that seems to be unique to Neanderthals.
“We were lucky we found a variant that had not been described in modern humans,” says co-author Michael Hofreiter of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “That made it unlikely to be human contamination.”
The researchers re-sequenced the applicable region of the gene multiple times, then asked two additional labs to repeat the experiments using fresh extracts. They also sequenced fragments of the mc1r gene from the researchers in each lab, as well as the archaeologists and palaeontologists who had handled the fossils. And they searched databases containing mc1r sequence from 2,800 humans and tested several hundred additional samples.
In the end, they had surveyed more than 3,700 humans, and none contained the Neanderthal sequence. “If it is in the modern human population, it’s at an extremely low frequency,” says Hofreiter.