LEIPZIG, Germany — Many people’s hair color, skin tone, and even mood, are likely due in part to sexual rendezvous between their human ancestors and Neanderthals many thousands of years ago, a new study finds.
Scientists at the Max Planck Institute for Evolutionary Anthropology recently took a deeper look into the influence of the two percent of Neanderthal DNA that most non-African people today carry in their genes. While genetic evidence of human interbreeding with Neanderthal has been known about for some time, researchers have only recently been able to take a more elaborate dive into what those genes do.
That new capability comes largely thanks to the UK Biobank pilot study that’s made available genetic, physical, and lifestyle information from over 112,000 participants.
“We can now show that it is skin tone, and the ease with which one tans, as well as hair color that are affected,” says study leader Janet Kelso in a press release.
The researchers added that a particularly interesting aspect of their study was the discovery that Neanderthal alleles (variant forms of genes) matched up with both lighter and darker skin tones and hair colors.
“These findings suggest that Neanderthals might have differed in their hair and skin tones, much as people now do” explains the study’s first author Michael Dannemann.
Inspired by earlier studies that showed associations between Neanderthal DNA and disease risk, Kelso said their team wanted to find the “influence Neanderthal DNA might be having on ordinary variation in people today.”
In addition to affecting hair and skin tones, the researchers write that there are also closely linked genetic influences on less tangible traits such as mood, sleep patterns, and even smoking habits. They said this is likely due to Neanderthal’s move northward out of Africa much earlier than modern humans. Accordingly, Neanderthal are speculated to have been more adjusted to the lower light levels in the Northernly climate.
“Skin and hair color, circadian rhythms and mood are all influenced by light exposure,” the researchers explain in the study findings. “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.”
While the UK Biobank’s genetic data already includes an unprecedented amount of additional information on traits related participants’ physical appearance, diet, sun exposure, behavior, and disease, Dannemann and Kelso say they hope that even more data will soon be available to allow them to continue exploring the influence of Neanderthal DNA.
And while their research focuses specifically on Neanderthal influence, it turns out Neanderthal weren’t the only other species getting amorous attention from humans. Other recent DNA studies have been uncovering the genetic impact of interbreeding episodes with several other types of hominids. One such study found DNA evidence of the influence of an unknown “ghost species” on an important gene affecting our saliva.
No doubt many more discoveries are just around the corner, especially due to the availability of large databases such as the UK Biobank, which notes on its website that scientists are invited to apply to use its resources in their own research.
The findings by Dannemann and Kelso were published recently in a paper in the American Journal of Human Genetics.