Tibetans live on high mountains thanks to 'extinct relatives'

According to a recent report by scientists, the reason that Tibetans can live in high altitude areas is due to a special gene, inherited from an extinct genus of humanity.

The ancestors of Tibetans today possessed an important variant of a gene that helps regulate oxygen in the blood by crossing with a human named Denisovan.

At the same time as the Neanderthals and also the same fate as them, may have been wiped out by the presence of modern Homo sapien, Denisovan and their presence in the history of human development only scientists discovered about four years ago.

The existence of Denisovans is determined through a piece of finger bone and two molars excavated at Denisovan Cave, south of Altai Mountain, Siberia. These clues date to about 80,000 years ago.

The gene sequence showed that before the Denisovans disappeared completely as a separate branch, they combined with the Homo sapiens and left traces left in today's human genome.

Tibetans live on Mount Karuola.(Source: AFP)

In a study published in Nature, scientists in China, Tibet and the United States compared the genomes of 40 Tibetans and 40 ethnic Han Chinese.

Research has shown that deep within the Tibetan gene code is an unusual variant of a gene called EPAS1 . This gene regulates the production of hemoglobin, the type of oxygen transport molecule in the blood.

EPAS1 is activated when blood oxygen levels decrease, causing the body to produce more hemoglobin.

At high altitudes, the common variants of this gene cause the human body to produce too much hemoglobin and red blood cells, making the blood more dense and difficult to circulate, a cause of hypertension, infants. low birth weight and neonatal mortality.

However, the variation found in the Tibetan genome increased the amount of hemoglobin at a much lower level, thus avoiding the problems associated with the lack of oxygen in those who moved to live in the sites where altitude greater than 4,000m.

Rasmus Nielsen, professor of biology at the University of California, Berkeley, USA, told bieeta: 'We have very clear evidence that this version of the gene comes from Denisovans. This shows a very clear and direct way, that people evolve and adapt to new environments by taking genes from other species. "

The variant of the EPAS1 gene in Tibetans almost exactly coincides with the Denisovan model.

However, except for Han ethnic people, there are no traces of this particular variant in the genome of other ethnic groups associated with Denisovans, including Melanesians with the proportion of diatomic genomes. highest transmission from Denisovan people, up to 5%.

The study hypothesizes that the Homo sapien groups were out of Africa and crossed with Denisovans during migration through Central Asia to China.

This group of migrants then split into two small groups, one migrating to Tibet, the other staying to dominate the lowlands, and gradually becoming the Han ethnic people today.

According to the survey results, thanks to the continued reproduction within each tribe, 87% of Tibetans preserved the rare variant of EPAS1 gene, compared to only 9% of Han ethnic people, although they with ancestors.

Scientists believe that many other mysteries about human genetic treasure will be revealed in the future.