Tibetans show evolutionary changes in at least 30 genes that help them cope with the challenges of life at such a high altitude.

Tibetans live at altitudes of 13,000 feet, breathing air that has 40 percent less oxygen than is available at sea level, yet suffer very little mountain sickness. The reason, according to a team of biologists in China, is human evolution, in what may be the most recent and fastest instance detected so far.

Comparing the genomes of Tibetans and Han Chinese, the majority ethnic group in China, the biologists found that at least 30 genes had undergone evolutionary change in the Tibetans as they adapted to life on the high plateau. Tibetans and Han Chinese split apart as recently as 3,000 years ago, say the biologists, a group at the Beijing Genomics Institute led by Xin Yi and Jian Wang. The report appears in Friday’s issue of Science.

Continue reading: http://www.nytimes.com/2010/07/02/scien ... ef=science

This strikes my as a typical tabloid take on a scientific issue. It encourages the old idea of peoples splitting away from one another as if a single tribe split, one went up the mountain and the other went into the valley. Real life is always a lot more complicated.

Let us assume for the moment a simplified theoretical example that a group simplistically called 'Han Chinese' went up the mountain into Tibet 3,000 years ago. Chances are they would have found people already living there. They would have intermarried and the resulting mixture would be the ancestors of the Tibetans.

Maybe the Han Chinese and their language became dominant. Maybe their DNA forms a large part of modern Tibetan DNA. But maybe as well some of the long adapted genes of the pre-Han population entered the mixed population and because of their advantages did very well in the ensuring centuries. I don't see that we can say that these genes evolved over 3,000 years unless we know that the area was uninhabited before that.