WASHINGTON (Reuters) – A jawbone found in a cave on the Tibetan plateau in China provides startling information about the denizens, the enigmatic extinct cousins of Neanderthals and our own species, including pioneers of high altitude environments.
The scientists described on Wednesday the new crucial fossil: the right half of a teenager's lower jaw, including two teeth, dating to 160,000 years ago.
The only fossils previously known to Denisovan were three teeth and some fragments of bones unearthed 2,400 kilometers away in Siberia at a place called the Denisova cave.
The Chinese fossil, found by a Buddhist monk in 1980 in Xiahe County, China, and later given to scientists, revealed intriguing details about the Denisovans' geographic expansion, their physical appearance, and their unexpected ability to conquer extreme environments.
The Baishiya Karst cave fossil at 10,760 feet above sea level showed not only that the Denisovans were widely distributed in eastern Eurasia but also that they inhabited an inhospitable environment of high altitude and low oxygen.
"It must have been very difficult to live there as a hunter-gatherer and still managed to be there," said University of Copenhagen molecular anthropologist Frido Welker, one of the researchers in the study published in the journal Nature.
Our species, Homo sapiens, did not populate this area until about 40,000 years ago, having first appeared in Africa just over 300,000 years ago.
"The inhabitants of Denisovans may have adapted to a wide range of different environments," said archaeologist Dongju Zhang of Lanzhou University in China.
The researchers failed to extract DNA from the fossil, but extracted proteins from one of the molars to determine their Denisovan identity.
"Proteins can survive about 10 times longer than DNA in fossils," said paleoanthropologist Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Germany.
Proteins came from collagen, a component of connective tissue in parts of the body, including dentin, a part of the teeth.
The existence of Denisovans was unknown until researchers in 2010 announced the discovery of the remains of Siberia, with DNA tests showing that they were a sister group to the Neanderthals, the extinct human species that resided in parts of Eurasia. Both experienced significant interactions with Homo sapiens, including crossing, before disappearing for reasons not fully understood.
The new fossil offers hints about what the Denisovans looked like. "The chin area is receding strongly and the preserved teeth were exceptionally large," Hublin said.
Some distant modern Asian populations, particularly in Papua New Guinea, have significant small amounts of DNA derived from Denisovans, suggesting that they had a broad geographic presence.
Report of Will Dunham; Edition by Sandra Maler