Thanks to a gene found in an extinct human race and common among the Tibetan population, humans are able to survive in high altitudes.

According to BBC News, researchers found an EPAS-1 gene variant to match that found in the Denisovan people. The gene responsible for managing blood oxygen is common among the people of Tibet, who live year-round at an altitude of about 4,000m.

The researchers published a study in the journal Nature.

Like the Neanderthals, the Denisovans contributed DNA to modern humans, after they interbred and spread to Africa. Whereas scientists have determined Neanderthals to have appeared 400,000 years ago and lasted until 35,000 years ago, not as much is known about the Denisovans.

Scientists know of the Denisovans from the DNA found in a particularly large tooth and a finger bone fragment discovered in central Siberia that dates back 40,000 to 50,000 years. Fortunately for the scientists analyzing that sample, the pinky finger yielded an entire genome sequence.

"We have very clear evidence that this version of the gene came from Denisovans," study co-author Rasmus Nielsen, of the University of California (UC) at Berkeley, told BBC News. "If you and I go up to high altitude, we'll immediately have various negative physiological effects. We'll be out of breath, we might suffer from altitude sickness."

The study contributes to the history of human ancestors interbreeding; for the Tibetans, it means their ancestors likely interbred with the Denisovans.

"The Denisovan-like DNA we found in the genome of Tibetans implied that the adaptation to local environments could be facilitated by gene-flow from other hominins who have been adapted to such environments," study co-author Xin Jin, a UC research scientist, said in a press release. "This unique finding may help us re-examine the similar fast-evolution cases in the future."

Nielsen told BBC News the EPAS-1 gene was a clear match to the Denisovans, but also in large part because it was a major miss when compared to Neanderthal DNA.

"We compared it to Neanderthals, but we couldn't find a match. Then we compared it to Denisovans and to our surprise there was an almost exact match," he said. "After the Denisovan DNA came into modern humans, it lingered in different Asian populations at low frequencies for a long time.

"Then, when the ancestors of Tibetans moved to high altitudes, it favored this genetic variant which then spread to the point where most Tibetans carry it today."