Tibetans evolve the fastest in the world

Life on a height of 4,900 m forces Tibetans to evolve very quickly to survive.

A young Tibetan girl.Photo: peopledaily.com.cn .

The concentration of oxygen in the atmosphere on the Tibetan plateau, China is only 60% of the air at sea level. Therefore, when people in other places come to Tibet, they will lose their strength very quickly and easily get a headache. If women in the lowlands start to become pregnant when they come to Tibet, they will give birth to low-birth-weight babies and have a high risk of death. However, Tibetans do not encounter these problems.

Livescience said molecular biologist Rasmus Nielsen of the University of California in the United States and experts from the Beijing Genetic Institute mapped the genomes of 50 unrelated people in two Tibetan autonomous villages. of China. The two villages are located at elevations 4,300 m and 4,600 m. They also map the genes of 40 Han Chinese in Beijing.

After comparing the Tibetan gene map with the Han Chinese in Beijing, the team found that about 30 mutations of genes frequently appeared in Tibetans than the Han. Nearly half of them control the body's use of oxygen.

A gene can exist in many states. Each specific state of the gene is called an allede.

According to AFP, the fastest rate of change occurs in a gene called EPAS1. Tibetans with two recessive alleles of EPAS1 have significantly lower red blood cells than normal people. A recessive allele appears only in Han people with a frequency of 9%, but in Tibetans the frequency increases to 87%.

"This is the fastest genetic change that scientists have ever seen in humans. A lot of people have lost their lives because they do not have genes that are suitable for life in Tibet," AFP quoted Nielsen.

The study also showed that the ancestors of Tibetans separated from Han people about 2,750 years ago. When they reached the Tibetan plateau, only those with biological characteristics suitable for low-oxygen life survived.

Many historical evidence shows that humans lived on the Tibetan Plateau more than 3,000 years, Nielsen stressed. He and his colleagues thought that Tibetans could integrate into people who lived here, or replaced them.