Tibetan family travelling to Pedruk.
Credit: Wikimedia
WASHINGTON: Tibetans took less than 3,000 years to adapt to living at high altitude, said a study that could lead to insights on diseases linked to pre-birth oxygen deprivation such as epilepsy.
"This is the fastest genetic change ever observed in humans," said biologist Rasmus Nielsen, from University of California Berkeley who led the statistical analysis and genome-wide comparison between the Tibetans and the Han Chinese.
The Tibetan-Han Chinese split
According to the study, published in the journal Science, the Tibetans and the Han Chinese split into two separate populations some 2,750 years ago, with the larger group moving to the Tibetan plateau where it dwindled while the low-elevation Han expanded dramatically.
The Tibetans, however, quickly evolved a unique ability to live above 4,000 meters (13,000 feet), where oxygen levels are 40% lower than those at sea level.
"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," said Nielsen.
Similarities to the 'super athlete gene'
Comparing the genes of both ethnic groups, researchers found more than 30 genes with DNA mutations that have become more prevalent in Tibetans than Han Chinese, nearly half of which are related to how the body uses oxygen.
One mutation in particular spread from fewer than 10% of the Han Chinese to nearly 90% of all Tibetans. It is near a gene called EPAS1, a so-called 'super athlete gene' identified several years ago that is associated with improved athletic performance, Nielsen said. The gene codes for a protein involved in sensing oxygen levels and perhaps balancing aerobic and anaerobic metabolism.
The new findings could steer scientists to still unknown genes that play a role in how the body deals with decreased oxygen, and perhaps explain some diseases, including schizophrenia and epilepsy, associated with oxygen deprivation in the womb, Nielsen said.
