Denisovan Jawbone Discovered Outside Siberia Shows Our Ancient Relatives Were First to Reach Tibetan Plateau

For the first time, scientists have discovered evidence of Denisovans—our long extinct, ancient relatives—outside of Siberia. Researchers found a 160,000-year-old jawbone belonging to the hominin species in a cave on the Tibetan Plateau, suggesting that they had not only expanded in range, but had adapted to life at high-altitude.

Denisovans were a sister species to Neanderthals. They branched away from the human lineage over half a million years ago, and diverged from Neanderthals around 300,000 years ago. Until now, evidence of their existence has been scant, having only been discovered in 2008. Furthermore, their remains have been limited to the Denisova Cave in southwest Siberia.

However, their importance to the story of human evolution is critical. Analysis shows that—as with Neanderthals—ancient humans interbred with Denisovans, and people from Asia, Australia and Melanesia still carry some of their DNA today.

In the latest study, published in the journal Nature, scientists from Europe and China have now reported the first evidence showing Denisovans were present outside Siberia. The jawbone was found in the Baishiya Karst Cave at an altitude of over 10,700 feet. Dating showed the bone was at least 160,000 years old—meaning Denisovans were the first hominins ever to reach this region of Earth. It is thought that humans reached the Tibetan Plateau around 30,000 to 40,000 years ago.

The team was not able to find DNA in the jawbone, but they were able to extract proteins from one of the teeth. This allowed them to identify the species as being closely related to the population of Denisovans found in Siberia. Researchers say that the adaptations that allowed this Denisovan to survive at such a high altitude may have been passed down to the people who now live in the area.

Study author Jean-Jacques Hublin, from the Max Planck Institute for Evolutionary Anthropology in Germany, told Newsweek he believes Denisovan populations—or Denisovan-like populations—were present over a large area in Asia. "I suspect a large proportion of the Chinese hominin fossil record is actually composed of Denisovans," he said. "I am certain the Baishiya Karst Cave will provide more discoveries in the course of planned excavations."

Chris Stringer, from the U.K.'s Natural History Museum, said the jawbone is a "very significant find" for numerous reasons, including the location and the morphological features that could show other fossils from archaeological sites in China are also Denisovan. He added that, while we should remain cautious, the ancient protein analysis used in the study is important: "The technique shows great promise for mapping the relationships of fossil hominins where ancient DNA is not preserved."

Thomas Higham, from the University of Oxford, U.K., said the find marks the start of our understanding of how Denisovans were distributed around the globe. "What is intriguing is that we already know Denisovan DNA was crucial in allowing modern-day Tibetans to survive in high altitudes, and here we have an actual Denisovan fossil on the Tibet plateau," he told Newsweek.

"In addition, and perhaps of more significance in the longer term, the identification of the Denisovan mandible on the basis of proteomics rather than DNA is hugely exciting. It means that in places where DNA does not survive it becomes possible to use this method to identify them. Since proteins survive for longer than DNA, this opens up exciting new avenues."