Researchers have found surprising links that show that Neanderthal ancestry influences our immune system today in ways more nuanced than previously recognized. Their work is published in the journal Genome Biology and Evolution.
Viruses account for an estimated 10–20% of the global disease burden. Many DNA viruses can persist in the body for a lifetime, and virus load varies greatly even among people without symptoms. Throughout human history, they have posed persistent and rapidly evolving threats, placing strong adaptive pressure on our immune system.
Previous research has shown that many genetic variants involved in immunity bear the marks of these evolutionary battles—including signatures of natural selection and contributions from interbreeding with archaic humans.
While Neanderthal ancestry has previously been associated with beneficial effects in RNA virus defense, the new study highlights a contrasting trend for DNA viruses.
Because of past admixture with archaic humans, around 2% of the genome of present-day non-Africans is composed of Neanderthal DNA and an additional 2–4% of people in Oceania of Denisovan ancestry. These introgressed sequences have shaped many biological traits, including immunity. But their role in defenses against DNA viruses has remained largely unexplored.
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