Various evolutionary adaptations have allowed Tibetans to live at high altitudes without suffering from mountain sickness . Lhasa, the capital, is located at 3,650 meters above sea level, but the average altitude of the region exceeds 4,000 meters and there are towns that exceed 5,000, such as Wenzhuan, located at 5,100 meters above the sea next to the Dangla Mountains. .
Scientists have long been investigating the keys to this ability to live in hypoxic conditions, in which the body is deprived of the necessary oxygen supply.
Well, a recent study by the Beijing Genomics Institute (BGI) together with the University of California, published in the journal Nature , shows that the secret surely comes from the crossing of genes from the ancient inhabitants of the Tibet with DNA from Denisovan individuals , an extinct species of hominids that inhabited Asia between one million and 40,000 years ago.
The EPAS1 gene is known as that of hypoxia because its mutations are associated with differences in the concentration of hemoglobin in the blood and it is known that certain variants of this gene protect inhabitants from mountain sickness. In the aforementioned study, the researchers resequenced the DNA region around EPAS1 in 40 Tibetans and 40 Han people from other regions of China.
The result is that the gene in Tibetans has a constitution that has only been observed in the genome of extinct Denisovans and not in other current populations of the world, with the exception of some individuals from southern Han Chinese populations and a single individual from the Han ethnic group from Beijing.
Denisovan gene flow to Tibetans could facilitate their adaptation to harsh high mountain environments. Scientists had previously found evidence of mixing with desinovans throughout Southeast Asia as well as in Melanesia.
Taking these findings into account, the researchers suggest that the ancestors of the Tibetans must have interbred with the Denisovans , which could explain the presence of their genetic type outside of Melanesia.
