Pic : An exhibit at the Neanderthal museum in Krapina, Croatia.
According to a Guardian newspaper article by Ian Sample, the genetic composition of Neanderthals links humans with serious illness. October 2020.
Modern humans and Neanderthals could be forgiven for having other issues on their minds when they interbred in the stone age. But according to researchers, those ancient couplings laid a grim foundation for deaths around the world today.
Scientists have claimed that a strand of DNA that triples the risk of developing severe Covid-19 was passed on from Neanderthals to modern humans. The genetic endowment, a legacy from more than 50,000 years ago, has left about 16% of Europeans and half of south Asians today carrying these genes.
The origins of the risk genes came to light when scientists in Sweden and Germany compared the DNA of very sick Covid-19 patients with that from Neanderthals and their mysterious sister group, the Denisovans. The stretch of DNA that makes patients more likely to fall seriously ill closely matched that collected from a Neanderthal in Croatia.
“I almost fell off my chair because the segment of DNA was exactly the same as in the Neanderthal genome,” Hugo Zeberg, an assistant professor at the Karolinska Institute in Stockholm, told the Guardian.
Zeberg and his co-author, Svante Pääbo, director of the Max Planck Institute of Evolutionary Anthropology in Leipzig, suspect the Neanderthal genes have persisted in modern humans because they were once beneficial, perhaps helping to fight off other infections. Only now – when faced with a new infection – has their downside been exposed.
It is unclear how the genes may worsen Covid-19, but one gene plays a role in the immune response and another has been linked to the mechanism the virus uses to invade human cells. “We are trying to pinpoint which gene is the key player, or if there are several key players, but the honest answer is that we don’t know which are critical in Covid-19,” Zeberg said.
According to the study, published in Nature, the cluster of genes on chromosome three are most commonly found in Bangladesh, where 63% of the population carry at least one copy of the DNA sequence.