DNA belonging to Denisovans – the ancient human ancestor – discovered in a Tibetan cave may be only 45,000 years old, scientists say.
The ancient Denisovan mitochondrial DNA was recovered in sediments from Baishiya Karst Cave, a limestone cave at the northeast margin of the Tibetan Plateau, 3,280 meters above sea level.
Samples indicate Denisovans occupied the high-altitude cave from around 100,000 to 60,000 years ago, and also possibly as recently as 45,000 years ago.
If the DNA is indeed only 45,000 years old, the species would have lived alongside modern humans in northeast central Asia.
Site of Baishiya Karst Cave, a Tibetan Buddhist sanctuary and a high-altitude paleoanthropological site for researchers
Denisovans, a group of extinct hominins that diverged from Neanderthals about 400,000 years ago, may have more widely inhabited northeast central Asia than scientists previously thought.
Samples of sediments were analysed by an international team including Charles Perreault at Arizona State University.
'When we started developing this project about 10 years ago, none of us expected Baishya Cave to be such a rich site,' he said
'We've barely scratched the surface – three small excavation units have yielded hundreds of stone tools, fauna and ancient DNA. There's a lot that remains to be done.'
'Future work in Baishiya Cave may give us a truly unique access to Denisovan behavior and solidifies the picture that is emerging, which is that Denisovans, like Neanderthals, were not mere offshoots of the human family tree.
'They were part of a web of now-extinct populations that contributed to the current human gene pool and shaped the evolution of our species in ways that we are only beginning to understand.'
By examining the sediment of Baishiya Karst Cave located on a high plateau in Tibet, researchers identified ancient mitochondrial DNA from Denisovans, indicating their presence possibly 45,000 years ago
A mandible fossil (the 'Xiahe mandible') from the same cave, which was dated to 160,000, had been previously identified as Denisovan, based on a single amino acid position.
This new study of the DNA dispels any doubt left that the Denisovans occupied the cave, according to the researchers.
Evidence of archaic hominins this far above sea level is unusual due to the severity of the conditions at high altitude.
Life on the plateau is harsh due to its thin air, and humans can develop altitude sickness anywhere above 2,500 meters above sea level.
Presence of the DNA suggests the Denisovans may have evolved adaptations to high altitude, much like modern Tibetans.
The dates of the sediments with mitochondrial DNA, along with the older 160,000-year-old Xiahe mandible, suggest that the Denisovans have been on the Plateau continuously for tens of thousands of years.
Pictured, the Xiahe mandible remains. The Denisovan jawbone was originally discovered in 1980 by a local monk
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