Ancient Neanderthal DNA may have little impact on modern humans, a new study claims

25 Dec 2020

Modern humans from all over the world carry traces of Neanderthal DNA in their genomes. In fact, it is so common that people often think they got their red hair, freckles, or even conditions like narcolepsy from these ancestors. However, a recent study might prove this belief to be nothing more than a misconception.

According to a recent study on tens of thousands of Icelanders, the Neanderthal legacy might have little to no impact on modern humans’ physical traits and genetic susceptibility to diseases and conditions.

Around 10 years ago, paleogeneticists established that most Europeans and Asians inherited 1% to 2% of their genomes from Neanderthals. Meanwhile, Melanesians and Australian Aboriginals got 3% to 6% of their DNA from the Denisovans.

Since then, a number of studies have theorized that gene variants coming from these ancient peoples might increase the risk of depression, blood clotting, diabetes, and other health conditions. It could also have an impact on the shape of our skulls, eye color, hair color, photosensitivity, and immune systems.

The new study, however, studied living Icelanders and looked for archaic DNA in their genome and challenged these previous claims. A team of researchers from the Aarhus University in Denmark studied the full genomes of 27,566 Icelanders and ended up with a significant catalog of 56,000 to 112,000 potentially archaic variants.

The researchers discovered that Icelanders inherited 3.3% of their archaic DNA from the Denisovans and 12.2% from unknown sources. Next, they calculated the association of Neanderthal and Denisovan DNA with 271 known traits. The team examined whole genomes, allowing them to evaluate whether modern human genes also influenced traits.

They discovered that most traits were better explained in association with modern gene variants and only 5 were notably influenced by archaic DNA. According to the leader of the research team, Laurits Skov, bioinformatician and a postdoc at the Max Planck Institute for Evolutionary Anthropology, men with one archaic variant were slightly less likely to develop prostate cancer, while men and women who carry two other variants are likely to have reduced height and accelerated blood clotting.

In comparison against previous studies, the team did not establish any statistically significant association between archaic DNA and traits like hair color, eye color, freckles, and autoimmune diseases like lupus, celiac disease, and Crohn’s disease. This led them to conclude that archaic Neanderthal DNA only has diminutive effects on traits.

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