bad link
Still works for me, but anyway, here:
Tibetans have Denisovan-like DNA for altitude adaptation: New Study
July 4, 2014 4:14 pm
DHARAMSHALA: A new study conducted by a group of researchers at Beijing Genomics Institute (BGI) have concluded that Tibetans have a special gene, derived from an extinct human species known as Denisovan, which helps them adapt to high altitudes.
The study published by Nature, an international weekly science journal, identifies a long segment of DNA shared by the extinct people known as Denisovans and Tibetans.
In the new study, scientists collected blood samples from 40 Tibetans and sequenced more than 30,000 nucleotides on a segment of DNA containing EPAS1, the gene that makes Tibetans so well-suited for life at high altitude. Then the scientists compared that sequence with those of 1,000 individuals representing the 26 human populations in the Human Genome Diversity Panel. They found the high-altitude gene in only 2 of the 40 Han Chinese in the panel and no one else.
“Re-sequencing the region around EPAS1 in 40 Tibetan and 40 Han individuals, we find that this gene has a highly unusual haplotype structure that can only be convincingly explained by introgression of DNA from Denisovan or Denisovan-related individuals into humans. Scanning a larger set of worldwide populations, we find that the selected haplotype is only found in Denisovans and in Tibetans, and at very low frequency among Han Chinese,” the study said.
“Natural selection by itself could not explain that pattern,” said Rasmus Nielsen, a computational biologist at UC Berkeley and an author of the study. “The DNA sequence was too different from anything else we saw in other populations.”
“Genetically, Han Chinese and Tibetans are very similar throughout the genome,” Nielsen said. “But for this particular gene, they are extremely differentiated from each other, which is something you only see with very strong or very recent selection.”
The plateau of Tibet is one of the most hostile places people inhabit. The air is thin and the weather cold. The Tibetans, however, have thrived there for tens of thousands of years. This might be attributed to the special gene the Tibetans have inherited from the Denisovans, as a result of interbreeding between Denisovans and Neanderthals.
The Denisovans are a mysterious branch of Homo. They were identified in 2010 by an analysis of the DNA of a bone discovered in a cave (occupied in the 18th century by a hermit called Denis) in the Altai Mountains in Russia. This bone was thought, when found, to be either Neanderthal or modern human, but the analysis showed it was neither. In the wake of that finding, a small percentage of Denisovan DNA has been discovered in various groups of people in Asia and the Pacific islands, Tibetans among them.