its use in Buddhist literature. The Central Tibetan language (the dialects of Ü-Tsang, including Lhasa), Khams Tibetan, and Amdo Tibetan are generally considered to be dialects of a single language, especially since they all share the same literary language, while Dzongkha, Sikkimese, Sherpa, and Ladakhi are generally considered to be separate languages. Although some of the Qiang peoples of Kham are classified by China as ethnic Tibetans, the Qiangic languages are not Tibetic, but rather form their own branch of the Sino-Tibetan language family. Ethnic origins Genetics Modern Tibetan populations are genetically most similar to other modern East Asian populations. They show relatively more genetic affinity for modern Central Asian than modern Siberian populations. They also share genetic affinity for South Asians. Tibetan people are genetically most closely related to Han Chinese, Bhutanese. Tibetans predominantly belong to the paternal lineage O-M175. Another study by Yang et al. 2017 found that Tibetans are genetically closely related to other Sino-Tibetan populations. Released in 2010 by University of California, Berkeley, a study identified more than 30 genetic factors that make Tibetans' bodies well-suited for high-altitudes, including EPAS1, referred to as the "super-athlete gene" which regulates the body's production of hemoglobin, allowing for greater efficiency in the use of oxygen. The genetic basis of Tibetan adaptations have been attributed to a mutation in the EPAS1 gene, and has become prevalent in the past 3,000 years. In fact, according to Rasmus Nielsen, UC Berkeley professor of integrative biology, this is "the fastest genetic change ever observed in humans". Genetic studies shows that many of the Sherpa people have allele frequencies which are often found in other Tibeto-Burman regions, in tested genes, the strongest affinity was for Tibetan population sample studies done in the Tibet Autonomous Region. Genetically, the Sherpa cluster closest with the sample Tibetan and Han populations. Additionally, the Sherpa had exhibited affinity for several Nepalese populations, with the strongest for the Rai people, followed by the Magars and the Tamang. Recent research into the ability of Tibetans' metabolism to function normally in the oxygen-deficient atmosphere above shows that, although Tibetans living at high altitudes have no more oxygen in their blood than other people, they have ten times more nitric oxide and double the forearm blood flow of low-altitude dwellers. Tibetans inherited this adaptation due to their Denisovan admixture. Nitric oxide causes dilation of blood vessels, allowing blood to flow more freely to