The Tibetan people’s genetic adaptations to the highlands seem to be of Denisova hominins heritage
A Group of geneticists, lead by Rasmund Nilson (California state university), found out that the transcription factor of EPAS 1 is responsible for protection from hypoxia (Huerta-Sánchez, 2014) and might be of deeply ancient origin. Nearly all of the Tibetan people possess it, as well as some of the examined Chinese (2 out of 40 in facts). It has not yet been found in any other human populations.
A version of EPAS 1 was discovered in 2010 (Beall et al., 2010; Yi et al., 2010).
Judging by the fact, that Tibetans widely possess this factor, unlike other people, we can only conclude that it been a subject for intense and positive natural selection. An obvious selection factor is the highlands.
Indeed, this gene’s codes of transcription factor HIF2alpha is responsible for the erythrocytes production and thus the blood hemoglobin level. Oddly enough, people homozygous for EPAS 1 have considerable lower blood hemoglobin level, then those who are heterozygous. The decrease of blood hemoglobin among Tibetans could possibly result in increased proneness to thrombosis, while oxygen is used more efficiently. However, it is just a guess.
Thus, it’s entirely different from the adaptation possessed by the inhabitants of Andes, as an example. They, instead have higher blood hemoglobin level. As it was recently discovered, this very gene version was found in the Denisova hominins genome, which in its turn, almost entirely corresponds to Tibetan’s.
Back then, both populations use to belong to a one group. It seems that ancestors of the modern Tibetans and Chinese inherited this useful alteration from Denisovans or their descendants. When this might have happened is yet to be discovered.
Translated by Ivan Shpurov.
Editor of English version: Ella Jones.
- Beall C.M., Cavalleri G.L., Deng L., Elston R.C., Gao Y., Knight J., Li C., Li J.C., Liang Y., McCormack M., Montgomery H.E., Pan H., Robbins P.A., Shianna K.V., Tam S.C., Tsering N., Veeramah K.R., Wang W., Wangdui P., Weale M.E., Xu Y., Xu Z., Yang L., Zarman M.J., Zeng C., Zhang L., Zhang X., Zhaxi P., Zheng Y.T. Natural selection on EPAS1 (HIF2alpha) associated with low hemoglobin concentration in Tibetan highlanders // Proceedings of the National Academy of Sciences of U.S.A., 2010. Vol. 107, N 25. P. 112459-11464.
- Huerta-Sánchez E., Jin X., Asan, Bianba Z., Peter B.M., Vinckenbosch N., Liang Y., Yi X., He M., Somel M., Ni P., Wang B., Ou X., Huasang, Luosang J., Cuo Z.X., Li K., Gao G., Yin Y., Wang W., Zhang X., Xu X., Yang H., Li Y., Wang Jian, Wang Jun, Nielsen R. Altitude adaptation in Tibetans caused by introgression of Denisovan-like DNA // Nature. 2014. 2 July. DOI: 10.1038/nature13408.
- Yi X., Liang Y., Huerta-Sanchez E., Jin X., Cuo Z., Pool J.E., Xu X., Jiang H., Vinckenbosch N., Korneliussen T.S., Zheng H., Liu T., He W., Li K., Luo R., Nie X., Wu H., Zhao M., Cao H., Zou J., Shan Y., Li S., Yang Q., Asan, Ni P., Tian G., Xu J., Liu X., Jiang T., Wu R., Zhou G., Tang M., Qin J., Wang T., Feng S., Li G., Huasang, Luosang J., Wang W., Chen F., Wang Y., Zheng X., Li Z., Bianba Z., Yang G., Wang X., Tang S., Gao G., Chen Y., Luo Z., Gusang L., Cao Z., Zhang Q., Ouyang W., Ren X., Liang H., Zheng H., Huang Y., Li J., Bolund L., Kristiansen K., Li Y., Zhang Y., Zhang X., Li R., Li S., Yang H., Nielsen R., Wang J., Wang J. Sequencing of 50 human exomes reveals adaptation to high altitude // Science./ 2010. Vol. 329, N 5987. P. 75-78.