NEW YORK — Tibetans living on the ‘‘roof of the world’’ can thank an extinct human relative for providing a gene that helps them adapt to the high altitude, a study suggests.
Past research has concluded that a particular gene helps people live in the thin air of the Tibetan plateau. Now scientists report that the Tibetan version of that gene is found in DNA from Denisovans, a poorly understood human relative more closely related to Neanderthals than modern people.
Denisovans are known only from fossils in a Siberian cave that are dated to about 50,000 years ago. Some of their DNA has also been found in other modern populations, indicating they interbred with ancient members of today’s human race.
But the version of the high-altitude gene shared by Denisovans and Tibetans is found in virtually no other population today, researchers report in an article released Wednesday by the journal Nature.
That suggests that Denisovans or close relatives of theirs introduced the gene variant into the modern human species, but that it remained rare until some people started moving into the Tibetan plateau, said the study’s main author, Rasmus Nielsen of the University of California, Berkeley.
At that point, it conferred a survival advantage and so spread through the Tibetan population, he said in an e-mail. It’s not clear whether the Denisovans were also adapted to high altitudes, he said.
The results show that as early members of today’s human species expanded outside of Africa and encountered new environments, they could call on their genetic legacies from other species, he said.
The Tibetan plateau rises above 13,000 feet in elevation. The genetic variant helps by affecting the amount of oxygen the blood can carry when a person is in thin air. Apart from Tibetans, it is found very rarely in Han Chinese and also exists in Mongolians and Sherpas, who are also related to Tibetans and may have picked it up relatively recently, Nielsen said. The researchers found no trace of it outside East Asia.