Sherpas, like Tenzing Norgay, who together with Edmund Hillary conquered Everest for the first time inherited genes from an extinct human subspecies that helps them cope with life high in the mountains.
A 160,000-year-old jaw found in a cave revealed that the ancient human species Denisovans lived at altitudes of 11,000 feet.
Scientists say the extinct Neanderthal-type human race lived on the Tibetan plateau more than 100,000 years ago.
They also found that the Denisovans transmitted genes that help some modern people survive at high altitudes.
The jaw was discovered in the Baishiya Karst cave in Xiahe, China, which stands at an altitude of 3,260 m.
It is the earliest hominin fossil ever found in the vast Himalayan region.
Previously, the physical evidence of Denisovans was known only from fossils of a single cave in Siberia.
Denisovan DNA traces were detected in Asian, Australian and current Melanesian populations, suggesting that they may have been widespread.
It is known that both the Denisovans and their human subspecies sisters, the Neanderthals, have crossed with ancestors of the people who live today.
Most intriguing is that the modern Sherpas – the native ethnic group in Nepal – and the Tibetans seem to have inherited Denisovan's genetic variants that help them cope with high altitudes.
The new finding suggests that the Denisovans settled in the Tibetan plateau thousands of years before the first modern humans, and the two groups later crossed.
Scientists were unable to find any DNA preserved in the fossil, but were able to extract proteins from one of the molars that proved to be Denisovan.
The well-preserved jawbone is robust with very large molars, characteristics shared by denizens and Neanderthals, according to a study published in the journal Nature.
A heavy carbonate crust covering the fossil allowed scientists to date at least 160,000 years old.
The oldest specimens of the "Denisova Cave" in Siberia are of a similar time period.
However, the Siberia site is only 700 meters (2,296 feet) above sea level.
Modern humans are not believed to have reached the Tibetan plateau until about 40,000 years ago.
Sherpas have lived in the Himalayas for at least 6,000 years and studies have shown that they have developed a physiology similar to that of a fuel-efficient car.
Your muscles get more mileage with less oxygen than those of the average person.
Sherpas have mitochondria – small rod-like mills in cells – that are extremely efficient in the use of oxygen.
As your count of red blood cells is increased in the rarefied mountain air, it remains below the point where blood thickens and twists the heart, causing altitude sickness.
Denisovan's jaw was originally discovered in 1980 by a local monk.
He donated to the sixth Gung-Thang Living Buddha, a Buddhist lama, or teacher, who went to the Lanzhou University in China.