Tibetan altitude gene came from extinct human species

Tibetans are comfortable at high altitudes where the air is thin. Now it seems a gene variant that gives them an edge over other people did not evolve in modern humans. It comes from an extinct species of human called the Denisovans.

Living on the roof of the world is hard. The air there carries less oxygen, making it harder to breathe and causing a host of problems. For instance, it is harder to conceive high up in the mountains. But Tibetans manage just fine.

Studies have linked their altitude adaptation to several genes including EPAS1, part of the system that helps the body react to low levels of oxygen. The Tibetan version of EPAS1 came from ancestors of the Nepalese Sherpa people and spread rapidly through the population 30,000 years ago, suggesting it is beneficial.

Now Rasmus Nielsen of the University of California, Berkeley, and his colleagues have compared Tibetan genomes with populations from around the world. No other modern group carries the Tibetan variant of EPAS1.

But they found the same gene variant in the genome of a Denisovan, an extinct species of human known only from a cave in the Altai mountains in east-central Asia.

"The study shows that one of the most spectacular cases of [genetic] adaptation in humans has its roots in Denisovans," says Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. "It is very satisfying to see that gene flow from Denisovans, an extinct group of archaic humans that we discovered only four years ago, is now found to have had important consequences for people living today."