The Denisovan man, in the family tree the sister of the Neanderthal, lived on the Tibetan plateau. This is evidenced by a Pleistocene human jawbone found in a cave in the area. The find means that this ancestor of the Tibetans could already withstand great heights.
Prehistoric people lived on the Tibetan plateau 160,000 years ago. This is evident from the analysis of a fossil jaw found in a cave near the village of Xiahe. The jawbone must have come from a Denisovan man, who can be considered the sister of the Neanderthal in the family tree. That is what a 19-strong international team of scientists writes in Nature. Until now there were only remains of Homo denisova known from a cave in Siberia.
Thin air
The jawbone is the first fossil hominin remains found on the Tibetan plateau. Because of the altitude – the cave was at 3,280 meters – the air is thin and the oxygen level is low. Apparently the Denisovan could handle that well.
Evolutionary biologist Nico van Straalen, who worked at the VU University Amsterdam until his retirement and was not involved in the Tibetan discovery, is not surprising. “Today's Tibetans have an abnormal variant of a certain gene, EPAS1, which plays a role in adapting to thin air. It was already known from previous research that this is very similar to the Denisova variant of this gene.” The present day Tibetan probably even inherited the gene from the Denisova. It was therefore expected that this primordial man already lived at great heights.
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Widespread
Although so far little remains of Homo denisova been found, this human species must have existed in a fairly large area:its DNA can still be found in Australians, Asians and Melanesians. This is probably a result of hybridization - mixing of different human species - when Homo sapiens from Africa to Southeast Asia and Australia, thinks Van Straalen.
“And there may have been another find after all, at Xuchang in central China,” he adds. In 2017, a Chinese research team found fossil skull fragments there, of a species they tentatively refer to as "archaic humans." Van Straalen:“That could very well be a Denisova, many paleontologists think. But yes, that does not fit the theory of multi-regional evolution that the Chinese adhere to.” In this theory, different versions of modern humans have emerged over the course of history, in different places.
Find
The jawbone – actually it was only the right half – was found in 1980 by a Tibetan monk, in the Baishiya karst cave near Xiahe. He gave it to the "living Buddha" the sixth Gung-Thang, who eventually passed it on to Lanzhou University. In more recent excavations in the same cave, scientists also found carved stones (artifacts) and animal bones with cut marks.
The researchers found no traces of DNA in the jawbone, but did succeed in extracting proteins from the molars. Analyzes of these primordial proteins indicated that the jaw belonged to a hominin very closely related to the Denisovans found in Siberia in 2010. The age of at least 160 thousand years was confirmed by radiometric dating of the carbonate rock that enveloped the jaw. This uses the ratio of different isotopes in the rock – in this case uranium and thorium – which changes over time due to radioactive decay.