A new paper in Nature suggests the gene variant that allows Tibetans to thrive at high altitudes may have arisen in the mysterious Denisovans, an extinct branch of hominid that co-existed with modern humans and Neanderthals. Denisovans were discovered through DNA analysis of a single bone from a cave in Siberia. Popular article in Slate. Just as Neanderthal ancestry contributed 1-4% of genes to modern people with ancestry outside of sub-Saharan Africa, Denisovan ancestry lives on in Southern Asia, and as the new research suggests, conferred benefits to the people of Tibet. From links here and here you can download the DNA letters for the first Denisovan discovered, along with a report generated based on personal genomics analysis.
Tibetans May Be Fastest Evolutionary Adapters Ever. "A group of scientists in China, Denmark and the U.S. recently documented the fastest genetic change observed in humans. According to their findings, Tibetan adaption to high altitude might have taken just 3,000 years. That's a flash, in terms of evolutionary time, but it's one that's in dispute."