Neandertal DNA could impact how you look

Neandertal DNA found to affect skin tone, tanning ease, and hair color.

Human and Neandertal interbreeding has left us with about two percent Neanderthal DNA in non-African people. Neandertal DNA was recently linked to human immunity and modern ailments. Now researchers have found that it also contributed to other characteristics, including skin tone, hair color, sleep patterns, mood, and even a person's smoking status. The new findings also suggest that Neandertals could have differed in their hair and skin tones to the same extent as people today.

We spoke to one of the authors, Janet Kelso at the Max Planck Institute for Evolutionary Anthropology, about the work.

ResearchGate: What inspired this study?

Janet Kelso: A 2016 study looked specifically at the influence of Neandertal alleles on disease phenotypes by using medical records for over 25,000 people. They identified a number of really interesting associations between Neandertal DNA and disease risk. We were interested in extending this idea to include non-disease phenotypes in order to determine what influence Neandertal DNA might have on ordinary variation in people today.

Because Neandertal alleles are rather rare in people today, we need to have a really large number of people to do this kind of analysis. The UK Biobank pilot study now provides such an extensive resource including genetic information as well as information about hundreds of common phenotypes in more than 100,000 individuals. We were therefore able to investigate the impact of Neandertal alleles on common phenotypes in modern humans.

RG: Can you tell us what you found?

Kelso: The main conclusion from our work is that Neandertal DNA contributes to non-disease phenotype variation in present-day people. Neandertal DNA affects skin tone and hair color. We also see effects of Neandertal DNA on height, sleeping patterns, mood, and smoking status in present-day Europeans. Interestingly, multiple Neanderthal alleles at different loci contribute to skin and hair color in present-day Europeans, and these Neanderthal alleles contribute to both lighter and darker skin tones and hair color, suggesting that Neanderthals themselves were possibly variable in these traits.

It’s very important to point out that we are not saying that Neandertals DNA alone is responsible for these traits. Most traits are complex, and there are many different variants in our genomes that contribute to each of them. In fact, we show that for most of these traits Neanderthal DNA variants do not contribute more than variants that have their origin in modern humans. Neandertal DNA is just one source of genetic variation that also contributes to these traits.

RG: How did you discover this?

Kelso: In each individual from the UK Biobank we start by identifying all the genetic variants that may have come from Neandertals. For each of these individuals we also have a few hundred different phenotypes (height, weight, ease of tanning, smoking status, exercise habits etc.) And we can then test for each Neandertal variant to see whether there is a significant association with any of the phenotypes.

RG: How does this differ from previous studies looking at the effect of Neandertal DNA?

Kelso: Our findings are rather consistent with previous inferences that genes involved in skin and hair biology were strongly influenced by Neandertal DNA. However, in those previous studies it wasn’t possible to determine precisely what aspect of skin or hair biology was affected.

By using the very large number of individuals from the UK Biobank for whom we have direct phenotype information, we can now show that it is skin color, and the ease with which one tans, as well as hair color that are affected.

RG: How many people are influenced by Neandertal DNA in things like skin tone, ease of tanning, or hair color?

Kelso: This of course varies for different traits. For example, in one of the regions we identified in this study Neandertal DNA is quite common, with up to 80 percent of the Europeans tested having Neandertal DNA. For other regions Neandertal DNA is less common and affects much fewer people.

RG: Is it possible for a person to tell by their appearance if they've been influenced by Neanderthal DNA?

Kelso: It’s not possible to tell simply by looking at someone which of their traits are influenced by Neandertal DNA! This is because almost every trait (such as hair color, or smoking risk) is influenced by many variants in our genomes. For each trait, only some of these variants come from Neandertals, many other variants do not.

Featured image courtesy of Mehmet Pinarci.