Why do Tibetans live on the roof of the world?

Scientists have discovered two genes that help Tibetans survive in the thin atmosphere of the highest land on the planet.

Tibetans have very low blood levels of blood to cope with hypoxia on the plateau.Photo: tibettravel.com.

With an average elevation of 4,900 m above sea level, Tibet is the highest plateau on earth and it is often called "the roof of the world". With an area of ​​2.5 million square kilometers, it has the highest mountain ranges on earth, such as the Himalayas.

On the Tibetan plateau, most people may suffer from tissue hypoxia - meaning that the amount of oxygen entering the tissue is too low compared to the normal level - leading to disorders of the cell's internal balance, a lack of energy accompanied by ischemia of the cell, causing acidosis, reducing protein synthesis, causing disruption of the body's processes. Consequently, people always feel stressed, tired, sick.

Some previous studies have shown that, to cope with low oxygen levels on the Tibetan plateau, people here breathe more times than those who live in areas of sea level. In addition, the blood vessels of Tibetans are also wider so they carry more oxygen to the tissues.

National Geographic reports, to find out why Tibetans can live normally where most human beings cannot survive, scientists from the Eccles Institute of Human Genetics at the University of Utah Medical School in the US Genes of 31 Tibetans are not related by blood. The team then compared their DNA to the DNA of 90 Chinese and Japanese living in lower regions.

The results show that in Tibetan people there are many gene variants that help people adapt to high life, such as oxygen-handling genes. These genes only exist in Tibetan bodies, not in humans living in lowland areas. In particular, the scientists discovered mutations in two genes - EGLN1 on chromosome 1 and PPARA on chromosome 22. The mutant version of the two genes makes the human body unable to produce more chromosomes. Hemoglobin (hemoglobin). That explains why the blood pigment concentration in Tibetan blood is very low.

Because hemoglobin is the oxygen-bearing component of red blood cells, low hemoglobin means less blood will be present.

'This seems counter-science. Normally, if people living in the lowlands move to higher places, the amount of blood pigment in the blood will increase to compensate for the low oxygen , 'Tatum Simonson, team leader, explained to National Geographic.

But Simonson said high levels of hemoglobin lead to bad phenomena such as high blood pressure, chronic fatigue.

"These negative syndromes may be the driving force behind a gene mutation in Tibetans, making their bodies unable to produce much blood pigment," Simonson said.

Simonson said, in the future, she and her colleagues will continue to explore the effects of mutant genes. She hopes new insights will help people prevent negative phenomena when they visit high lands.