The variant of the genes responsible for the coronavirus disease were passed on to humans by the Neandarthals, is very common in Bangladeshis, according to a new study.
This piece of the genome, which spans six genes on Chromosome 3, has had a puzzling journey through human history, the study found, reports The New York Times.
The piece of genome that the study found is responsible for the infection is common in those living in Bangladesh.
The study has been carried out by a pair of Swedish geneticists Svante Paabo and Hugo Zeberg. Germany's Max Planck Institute, Japan's Okinawa Institute of Science and Technology and Sweden's Karolinska institute are affiliated with the project.
Their findings were posted online on Friday and have not yet been published in a scientific journal.
According to it, 63 percent of the people in Bangladesh carry at least one copy of the genes. Across all of South Asia, almost one-third of people have inherited the segment.
Elsewhere, however, the segment is far less common. Only 8 percent of Europeans carry it, and just 4 percent have it in East Asia.
It is almost completely absent in Africa.
However, the scientists don't yet know why this particular segment increases the risk of severe illness from the coronavirus. But the new findings show how some clues to modern health stem from ancient history.
About 60,000 years ago, some ancestors of modern humans expanded out of Africa and swept across Europe, Asia and Australia. These people encountered Neanderthals and interbred. Once Neanderthal DNA entered our gene pool, it spread down through the generations, long after Neanderthals became extinct.
Most Neanderthal genes turned out to be harmful to modern humans. They may have been a burden on people's health or made it harder to have children. As a result, Neanderthal genes became rarer, and many disappeared from our gene pool.