Although it was already known that some Neanderthal genes had contributed to some body immunity, a recent study published today by the American Journal of Human Genetics has shown that they also left their mark on other characteristics such as skin tone or hair color.

Even sleep patterns or the chances of being or not smoking.

After humans and Neanderthals met many thousands of years ago, the two species began to cross, and although Neanderthals no longer exist, about 2 percent of the DNA of non-Africans living today comes from them.

Janet Kelso of the Max Planck Institute for Evolutionary Anthropology in Germany, who directed this study, explains that her team was interested in exploring the connections between Neanderthal DNA and non-disease traits.

In other words, they wanted to discover the “influence that Neanderthal DNA might have on ordinary variation in people today.”

Because alleles – each of the versions of a Neanderthal gene are relatively rare, researchers needed data that would represent a very large number of people.

Thus, they found these findings thanks to data provided by more than 112,000 participants in the UK Biobank pilot study.

The Biobank includes genetic data along with information on many traits related to physical appearance, diet, sun exposure, behavior and diseases of those people who have in their records.

Earlier studies had suggested that human genes involved in skin and hair biology were strongly influenced by Neanderthal DNA, but it was not clear how it went, explains Kelso.

“Now we can show that it is the tone of the skin, and the ease with which one tans, as well as the color of the hair the traits that have been influenced,” he adds.

“These findings suggest that Neandertals may have differed in their hair and skin tones, as people do,” adds study lead author Michael Dannemann.

Kelso points out that traits influenced by Neanderthal DNA, including pigmentation of the skin and hair, mood and sleep patterns, are related to exposure to sunlight.

When modern humans arrived in Eurasia about 100,000 years ago, Neanderthals had already lived there for thousands of years. They were probably better suited to lower and more variable levels of ultraviolet radiation from the sun than new arrivals from humans in Africa.

“Skin and hair color, circadian rhythms and mood are influenced by exposure to light,” the researchers wrote.

“We assume that their identification in our analysis suggests that sun exposure may have formed Neandertal phenotypes and that the flow of genes in modern humans continues to contribute to the variation in these traits today,” they add.

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