Before their extinction thousands of years ago, Neanderthal populations bred with humans and as a result, about 2 percent of the DNA in non-African people living today comes from them. Previous research has shown that some Neanderthal genes impacts human immunity and modern disease.
Now, however, it appears that Neanderthal DNA has contributed to a variety of other human characteristics as well, ranging from skin tone to whether a person picks up smoking, according to a report published Thursday in the American Journal of Human Genetics.
The study’s lead author Janet Kelso and her team became interested in exploring associations between Neanderthal DNA and various traits in people living today after reading an earlier study that identified connections between the ancient species’ genetic code and disease risk in modern humans.
Since Neanderthal alleles – alternative forms of a given gene – are fairly rare, the team needed to access data representing a large number of people. The researchers ultimately attained data representing more than 112,000 participants in the U.K. Biobank pilot study. The Biobank features genetic data and information on numerous traits related to diet, physical appearance, behavior, sun exposure and disease.
The team’s findings confirm previous research that suggested human genes involved in hair and skin biology were influenced greatly by Neanderthal DNA.
“We can now show that it is skin tone, and the ease with which one tans, as well as hair color that are affected,” Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology in Germany, said.
The researchers identified several different Neanderthal alleles that contribute to hair and skin tones. What the team found surprising, however, is that some of the alleles are connected to lighter hair colors and skin tones, while others are associated with darker variations.
“These findings suggest that Neanderthals might have differed in their hair and skin tones, much as people now do,” said first author Michael Dannemann, a postdoctoral research associate at the Max Planck Institute.
Kelso said the traits influenced by Neanderthal DNA are each connected to sunlight exposure. As Neanderthals had lived in Eurasia for thousands of years before humans arrived – roughly 100,000 years ago – the ancient species was likely well adapted to lower and more fluid levels of ultraviolet radiation from the sun than their human counterparts were accustomed to in Africa.
"Skin and hair color, circadian rhythms and mood are all influenced by light exposure," the team writes. "We speculate that their identification in our analysis suggests that sun exposure may have shaped Neanderthal phenotypes and that gene flow into modern humans continues to contribute to variation in these traits today."
The researchers plan to continue to explore Neanderthals’ influence on the traits of modern humans as as more data becomes available.
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