Some Neandertals Were Pale Redheads, DNA Suggests
for National Geographic News
|October 25, 2007|
Some Neandertals may have had red hair and pale skin, just as some modern humans do, according to a new genetic study.
The traits were likely more common in European Neandertals (often spelled Neanderthals), just as they are often seen in modern humans of European descent.
"I am quite sure this variant arose like the red hair variants in modern Europeans," said the study's lead author Carles Lalueza-Fox, of the University of Barcelona.
In the cases of both Neandertals and modern Europeans, he said, the gene mutation that caused fairer complexions spread only after the respective populations migrated from Africa.
Gene Keys Complexion Change
While studying Neandertal DNA samples, Lalueza-Fox's team found an unknown mutation in a key gene called MC1R.
Also present in modern humans, the gene regulates a protein that guides the production of melanin, which pigments hair and skin and protects from UV rays.
Variations in this gene's sequence limit melanin production in people with pale skin and red hair, although the particular mutation found by the researchers is not known to occur in modern humans.
The team tested the gene in living cells to see what effect the previously unknown variant would have had on the Neandertals who carried it. The test tube experiment showed that the variant suppressed the production of melanin, and thus likely gave the Neandertals who carried it red hair and pale skin.
Although it is not easy to find intact DNA from 230,000 to 30,000 years ago, Lalueza-Fox and his colleagues were able to study two separate samples unearthed in Italy and Spain.
The study was published today by the journal Science.
Skin Changes Similar in Humans, Neandertals
Lalueza-Fox believes the variant his team discovered was likely one of many that spread through ancient Neandertal populations by processes of natural selection.
"European [humans] have quite a lot of variation in this gene—not only red hair variants but also others," he explained, adding that humans have been in Europe for only about 40,000 years.
"The Neandertals, being there at least 400,000 [years], likely accumulated ten times more variation."
Neandertals are believed to have roamed Europe between 28,000 and 400,000 years ago.
James Noonan, a geneticist at the Yale University School of Medicine who was unaffiliated with the research, said Lalueza-Fox's conclusions were convincing.
"It's not surprising that there would be a Neandertal-specific MC1R variant that results in a partial loss of function (and thus lighter skin and hair)," he said. "Similar mutations have arisen independently in different modern human populations."
Another scientist who was not involved with the research, Henry Harpending, an anthropologist at the University of Utah in Salt Lake City, added that a number of genes that affect human skin color are still changing and spreading through Europe and Asia.
The particular genes that affects skin color are different in Europe and Asia, he said, but in both places, fairer complexions appear to be the result of broken versions of these genes.
"This paper suggests that Neandertals were light, or were getting light, in the same way, i.e., by selection for slightly broken genes," he said.
Scientists are not sure why the broken gene—and fairer complexions—would be spread by natural selection.
Yale's Noonan said geography was the likeliest explanation for the endurance of this trait in both modern humans and Neandertals—pigment advantage was likely less relevant in darker places.
Northern latitudes have "less sunlight and so less need for darker skin pigmentation to protect against UV-induced damage," Noonan said.
Though the genetic processes that helped to lighten their complexions may have worked similarly, humans have never displayed the same sequence seen in the ancient Neandertal gene samples.
"Both processes took place independently—that's the reason the Neandertal variant is not present in modern humans," Lalueza-Fox said.
The new find offers no evidence of interbreeding between humans and Neandertals, he added.
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