London: Neanderthal genes have contributed to human skin tone, hair colour, sleep patterns, mood, and even a person's smoking status, find a study.
The study, led by researchers from the Max Planck Institute for Evolutionary Anthropology in Germany, explored the "influence Neanderthal DNA might be having on ordinary variation in people today", said Janet Kelso, a biologist at the institute.
Earlier studies had suggested that human genes involved in skin and hair biology were strongly influenced by Neanderthal DNA, Kelso said. But it had not been clear how.
"We can now show that it is skin tone, and the ease with which one tans, as well as hair colour that are affected," Kelso said.
The researchers, reporting in the American Journal of Human Genetics, observed that multiple Neanderthal alleles contributed to skin and hair tones.
Further, some Neanderthal alleles are associated with lighter skin tones and others with darker skin tones. The same was true for hair colour.
"These findings suggest that Neanderthals might have differed in their hair and skin tones, much as people now do" added Michael Dannemann from the institute.
Importantly, Kelso noted that the traits influenced by Neanderthal DNA, including skin and hair pigmentation, mood, and sleeping patterns are all linked to sunlight exposure.
"Skin and hair colour, circadian rhythms and mood are all influenced by light exposure," Kelso said.
"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."
For the study, the team examined 112,000 participants genetic data along with information on many traits related to physical appearance, diet, sun exposure, behaviour, and disease.