We tend to think of the human-like people before us, like the Neanderthals, as part of our biological history that’s so far removed that it has little bearing on our current lives. After all, you don’t get to meet Neanderthals in the street. Or do you? For one, from 1.8% to 2.6% of the DNA in most modern people comes from the Neanderthals. A new study provides another important link – Neanderthals passed on a key genetic adaptation that kept us protected from killer viruses.
Sex between Neanderthals and homo sapiens is the reason for our genetic connection. The humans were on their way out of Africa into Eurasia, when they met the Neanderthals. Thanks to sharing a common ancestor about 500,000 to a million years prior, the sex between the species produced viable offspring.
What the new study found is that before they hooked up with modern humans, Neanderthals were in Eurasia for hundreds of thousands of years fighting off pathogens. As a result, their genomes developed an ability to survive viruses, which they gifted to us.
The study’s co-author David Enard, Ph.D. from the University of Arizona explained to Inverse that interbreeding was like a quick “antidote” for the homo sapiens to protect themselves. They suddenly faced an onslaught of new viruses.
Incorporating the genetic material that was already pre-adapted from the Neanderthals gave the homo sapiens a “fast-track route for adaptation”, shares Enard, adding “instead of ‘reinventing the genetic wheel,’ we just borrowed it from the Neanderthals.”
“Neanderthal genetic material was like a protective antidote because Neanderthals had likely been infected for a long time by the same viruses that were now harmful to modern humans,” says David Enard. “This long exposure means that Neanderthals had plenty of time to adapt against these viruses before modern humans showed up.”
Of course, not everything went smoothly when these two species met in the distant past. The scientists think they likely infected each other with the pathogens from their environments – in what’s called “the poison-antidote” model of exchanging genes. The sexual unions produced the antidote.
It also bears pointing out that modern humans get depression and cigarette addiction from the Neanderthals.