Trending Science: Fossil reveals first evidence of Neanderthal cousin
Jaw discovered in a Tibetan cave sheds light on mysterious ancient humans called Denisovans.
A 160 000-year-old fossil comprised of a powerful jaw and unusually large teeth has revealed new details about the Denisovans, according to a study published in the journal ‘Nature’. The enigmatic extinct cousins to Neanderthals and our own species lived at extremely high altitudes much earlier than the arrival of modern humans in the region about 40 000 years ago.
The jawbone was discovered by a monk in 1980 at Baishiya Karst Cave on the Tibetan Plateau, 3 280 m above sea level. It eventually found its way to China’s Lanzhou University. A research team there began analysing the fossil in 2016.
Adapting to high altitudes long before humans
Until now, it was thought that ancient humans couldn’t endure at such soaring heights and low-oxygen environments. “It must have been really tough to live there as a hunter-gatherer, and still they managed to be there,” University of Copenhagen molecular anthropologist Frido Welker, one of the researchers in the study, told ‘Reuters’. “Denisovans might have adapted to a wide range of different environments,” study author and archaeologist Dongju Zhang of Lanzhou University said.
Unable to extract DNA from the fossil, the researchers managed to extract proteins from one of the molars to determine its Denisovan identity. “Proteins can survive about 10 times longer than DNA in fossils,” explained co-author and paleoanthropologist Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Germany. He said that the fossil provides clues about the appearance of Denisovans: “The chin area is strongly receding and the preserved teeth were exceptionally large.”
Speaking to the ‘BBC’, Prof. Hublin expressed his surprise at the Denisovans’ unexpected ability to overcome harsh environments. “When we deal with ‘archaic hominins’ - Neanderthals, Denisovans, early forms of Homo sapiens - it’s clear that these hominins were limited in their capabilities to dwell in extreme environments.” He added: “If you look at the situation in Europe, we have a lot of Neanderthal sites and people have been studying these sites for a century-and-a-half now. The highest sites we have are at 2,000m altitude. There are not many, and they are clearly sites where these Neanderthals used to go in summer, probably for special hunts. But otherwise, we don’t have these types of sites.”
It’s in the genes
The research shows present-day Sherpas, Tibetans and neighbouring populations have a genetic variant that helps them to cope with oxygen deficiency at high altitudes. This variant can be traced back to Denisovans, likely acquired through interbreeding.
“We can only speculate that living in this kind of environment, any mutation that was favourable to breathing an atmosphere impoverished in oxygen would be retained by natural selection,” said Prof. Hublin. “And it’s a rather likely scenario to explain how this mutation made its way to present-day Tibetans.”
Prof. Hublin concluded in a Max Planck Institute press release: “Our analyses pave the way towards a better understanding of the evolutionary history of Middle Pleistocene hominins in East Asia.”