Ethnic Tibetans split off from the Han Chinese only 3,000 years ago and quickly developed their extraordinary physical adaptations to the high-altitude hardships of low oxygen, according to a new study published in the July issue of Science.
European Pressphoto Agency
A new study says that Tibetans had the fastest genetic change ever seen in humans. Above, dancers perform in Lhasa, capital of the Tibet Autonomous Region.
“This is the fastest genetic change ever observed in humans,” said Rasmus Nielsen, the University of Berkeley biology professor who led the statistical analysis, according to a statement by the university.
That quick acclimation came at a high price.
“For such a very strong change, a lot of people would have had to die simply due to the fact that they had the wrong version of a gene,” Nielsen said.
The study compared the genomes of 50 Tibetans and 40 Han, the majority ethnic group in China, and found the Tibetans had mutations in their DNA that let them better use oxygen. One mutation that occurs in only 10% of the Han was present in 90% of all Tibetans.
The mutation that give Tibetans a high-altitude edge is near what’s sometimes called the “super-athlete gene,” or more prosaically, EPAS1, because the gene is associated with better athletic performance, according to the statement.
The research could also shed light on genes governing schizophrenia and epilepsy, which are linked to oxygen deprivation in the womb.
The Berkeley researchers worked with data from the Beijing Genomics Institute in the southern China city of Shenzhen.
According to the research, the group that eventually became what are now known as Tibetans split off from a common ancestor 2,750 years ago. Those immigrants may have intermarried with or replaced the people already living on the plateau.
“We can’t distinguish intermixing and replacement,” Nielsen said. “The Han Chinese and Tibetans are as different from one another as if the Han completely replaced the Tibetans about 3,000 years ago.”