Oct. 5 (UPI) -- Researchers have identified several new traits in modern humans that are influenced by Neandertal genes.
Roughly 2 percent of the modern human genome is inherited from Neandertals. Previous studies have linked Neandertal DNA with a handful of modern diseases and immunity, proof our closest ancestors continue to impact our physiology.
Now a new study, published this week in the American Journal of Human Genetics, suggests Neandertal DNA also influences traits unrelated to disease, including skin tone, hair color, sleep patterns and mood.
Researchers surveyed the genomic data of 112,000 participants in the UK Biobank pilot study, searching for connections between genetic variations, or alleles, inherited from Neandertals and traits related to physical appearance.
The analysis confirmed what previous surveys had hinted at, connections between Neandertal alleles and modern hair and skin traits.
"We can now show that it is skin tone, and the ease with which one tans, as well as hair color that are affected," Janet Kelso, a researcher at the Max Planck Institute for Evolutionary Anthropology in Germany, said in a news release.
Researchers found some Neandertal alleles are linked with darker hair and skin tones, while other variations are linked with fairer hair and skin pigmentation.
"These findings suggest that Neandertals might have differed in their hair and skin tones, much as people now do," said researcher Michael Dannemann.
Researchers believe the genetic variations among Neandertals were influenced by sun exposure. Having lived in Eurasia for thousands of years before the arrival of the first humans from Africa, Neandertals would have already adapted to variable sunlight levels at higher latitudes. These adaptions could be passed down to interbreeding early humans.
"Skin and hair color, circadian rhythms and mood are all influenced by light exposure," researchers wrote in the new study. "We speculate that their identification in our analysis suggests that sun exposure may have shaped Neandertal phenotypes and that gene flow into modern humans continues to contribute to variation in these traits today."