DNA shows that Neanderthals spread viruses in humans

First, Enard has systematically reviewed the scientific literature for a list of 4,534 human proteins that interact with modern viruses such as influenza, HIV and hepatitis. Viruses evolve to have very specific interactions with the proteins of the cells they infect. An influenza virus could, for example, enter as a key in the "lock" of a cell surface protein, prompting the human cell to let it in. But modify this lock slightly and the virus will not get into the skin again; in other words, this cell is now resistant.

Enard explained that the Neanderthals had developed some resistance to the viruses that had to circulate among them in Europe. Modern humans, by contrast, have probably encountered these viruses for the first time. Thus, when they mated with Neanderthals, subsequent generations of inherited genes from Neanderthal-interacting proteins were more likely to survive. Other scientists have identified Neanderthal DNA segments in humans likely to present an evolutionary advantage. Enard has compared these to his list of 4,534 proteins that interact with the virus. Indeed, he discovered that the genes of the proteins interacting with the viruses were enriched in DNA of Neanderthal origin.

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Of course, this should work in the other way as well. Modern humans probably brought their own human viruses with them, and proteins interacting with a human virus should have been selected from Neanderthals. There is no live Neanderthal, but scientists have already sequenced the genome of more than 50,000 years old from a Neanderthal man discovered in Siberia, who had fragments of modern human DNA, suggesting a human ancestor. You can not draw radical conclusions from a single individual, but Enard discovered that the longer human DNA residues in this Neanderthal man also corresponded to proteins interacting with human viruses – proteins that could have protected his ancestors of human viruses.

The results are in perfect agreement with previous research that immune-related genes are common in persistent Neanderthal DNA segments in humans. "Pathogens have played an important role in human adaptations," says Emilia Huerta-Sanchez, a population geneticist at Brown University.

There were also unexplained patterns in Neanderthal and human DNA. Viruses belong to two major groups: those whose genetic material is encoded in DNA (such as adenoviruses and smallpox) and those whose genetic material is encoded in RNA (influenza, yellow fever, HIV, etc.). Enard discovered that it was specifically Neanderthal genes encoding proteins interacting with RNA viruses that are most likely to remain in the human genome, but only among Europeans and not Asians of l & # 39; Is. Other research has suggested that the ancestors of Europeans and East Asians probably had a distinct history of miscegenation with Neanderthals.