Tibetans Can Thank Ancient Humans for Gene That Lets Them Live the High Life

The physiological ability of ethnic Tibetans to thrive at miles-high elevations, unaffected by oxygen levels that leave lowlanders gasping, appears to have originated with Denisovans, a close relative of Neanderthals. Following on the news earlier this year that many modern humans have quite a bit of Neanderthal DNA, the finding is the latest example of the complex anthropological tapestry that is our genome. It also hints at a perhaps underappreciated reason for Homo sapiens' tremendous success: After leaving Africa, our ancestors picked up traits from the locals.
 "Maybe this happened many times throughout human history, and we just happened to detect it this time," said computational biologist Rasmus Nielsen of the University of California, Berkeley. "It suggests that getting genes from other species might have been important to our evolution."
 In an earlier study, Nielsen and colleagues observed that modern Tibetans have a different form of a gene called EPAS1, which is involved in a metabolic pathway that regulates the body's response to low-oxygen conditions. Though the researchers don't know exactly how that mutation operates, they suspect it plays an important role in the ability of Tibetans to thrive at high altitudes.
In the new study, Nielsen's group compared DNA from 40 Tibetans and 40 Han—the dominant ethnic group in China—with the Denisovan genome. The Denisovan EPAS1 gene, they found, almost completely matches the one found in Tibetans.