科学美国人60秒 SSS 2014-09-02

搜索关注在线英语听力室公众号：tingroom，领取免费英语资料大礼包。

 

Millions of Tibetans spend their days at average elevations⁴ of nearly 15,000 feet—that’s more than half the height of Mount Everest. Up there, the air is thin—with 40 percent less oxygen than at sea level. That lack of O2 would leave most Westerners struggling for breath, but Tibetans seem to breathe easy.

 

To find out how these highlanders cope, researchers compared the DNA of 90 Tibetans to that of people who are not altitude adapted. And they discovered a single change that prevents Tibetans’ blood from becoming dangerously clogged⁵ with red blood cells—a response that can be deadly for non-native mountaineers. The finding is described in the journal Nature Genetics.

 

This mutation appears to have originated just 8,000 years ago. But it’s so advantageous⁶ that today nearly 90 percent of Tibetans have it. While it’s virtually absent in even closely related lowland neighbors.

 

The finding demonstrates that a really useful mutation will always rise to the top.

 

— Karen Hopkin

分享到：