Tibetans’ ability to thrive in high altitudes without succumbing to hypoxia is due to a gene, EPAS1, inherited from an extinct hominin species, the Denisovans. This genetic adaptation allows Tibetans to live comfortably at heights where oxygen levels are up to 40% lower than at sea level. The Denisovans, discovered in 2010, were a sister species to the Neanderthals. They lived in Asia until around 40,000 years ago. In 2014, scientists found that EPAS1, a gene found in Tibetans but not in most other humans, was present in the Denisovan genome. This gene regulates the body’s production of haemoglobin, the molecule that carries oxygen in the blood.

Tibetans have a unique version of EPAS1, which allows them to maintain normal haemoglobin levels at high altitudes, avoiding the common problem of too much haemoglobin leading to thick, sludgy blood. A study found that Tibetans who lacked this gene variant were more likely to suffer from hypoxia. This discovery underlines the importance of interbreeding between species in human evolution, and the critical role of genetic adaptation in survival in different environments.

Go to source article: http://www.economist.com/news/science-and-technology/21606257-secret-tibetans-success-lies-ancestors-who-were-not-quite-human-life?fsrc=scn%2Ftw%2Fte%2Fpe%2Flifeatthetop