Neanderthal DNA may be affecting the way some humans sleep

Thousands of humans may still be walking the Earth with Neanderthal DNA — and not only that, but traces of the ancient stuff may be influencing skin tone, hair color, and even sleeping patterns in present-day Europeans, a study released Thursday from the Max Planck Institute for Evolutionary Anthropology found.

Using the genetic information of over 100,000 people in the U.K. Biobank, scientists discovered that Neanderthal genes, which make up 1 to 3 percent of the genetic code of people with European descent, may still have a small effect on some physical traits. No trait can be isolated to a particular gene; multiple genetic factors affect skin tone, for example, and Neanderthal genetic material only plays one part in determining the tone. But breakthroughs in researching Neanderthal DNA may help scientists understand how some genetic traits function.

Most interestingly, Neanderthal DNA has been linked to traits associated with light exposure like circadian rhythms, meaning the ancient genes may affect how people sleep in current times. Neanderthals had greater exposure to UVB rays while living on Eurasia for 100,000 years before they mated with Homo sapiens, so they had "more time to get used to a wider range of daylight," NPR explains.

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Scientists believe that people indigenous to Africa do not have Neanderthal DNA in their genetic code because their ancestors never migrated to Eurasia. The study is limited because the sample size did not extend beyond the U.K. Biobank, but researchers hope to gain access to other biobanks and databases in the future. Read more about the study at NPR.