A gene inherited from the Denisovans, an extinct human subspecies known mainly from a single finger bone found in a cave in Siberia, helps Tibetan people thrive at high altitudes.
A study led by Hao Hu and Chad Huff from the University of Texas in the US reveals that Tibetans utilise five gene variants that collectively make them well adapted to the low oxygen levels, extreme cold, elevated levels of ultraviolet light and limited food supplies that characterise high-altitude living.
The research, published in the journal PLOS Genetics, used entire genomes sequenced from 27 Tibetans.
As expected, the genomes contained two genes – EPAS1 and EGLN1 – previously identified as involved in adaptation to high-altitude life. However, the variant of EPAS1 was unique and found to be derived from the Denisovans.
The other four genes of interest, however, did not have the same archaic roots, leading the researchers to conclude that except for EPAS1 they “did not detect any evidence of high altitude adaptation from Denisovan gene alleles”.
The sequencing revealed two other genes, PTGIS and KCTD12, thought to be related to survival in low-oxygen environments, and a variant of VDR, which is linked to vitamin D metabolism and may help ameliorate the deficiencies that commonly affect people who live at great heights.
Hu and Huff also established that the Tibetan and Chinese Han sub-populations split very early, somewhere between 44,000 and 58,000 years ago, but gene flow between the groups didn’t end until 9,000 years ago.
Tatum Simonson from the University of California San Diego, US, one of the study’s co-authors, says the results provide pathways for comparative studies in other populations.
“This study provides further context for analyses of other permanent high-altitude populations, who exhibit characteristics distinct from Tibetans despite similar chronic stresses,” he says.
He adds that the work may also be useful for studying health problems such as sleep apnea, even in people who live close to sea level.
