A 160,000-year-old Denisovan jawbone found in a cave on the Tibetan Plateau is the first reported evidence of this ancient human group being present outside the Denisova cave in Siberia. This jawbone, described in Nature this week, represents the earliest known hominin fossil found on the Tibetan Plateau. The discovery indicates that Denisovans adapted to high-altitude, low-oxygen environments much earlier than the regional arrival of modern humans.
Denisovans are an extinct sister group to Neanderthals, known only from fossil fragments found at Denisova cave in southern Siberia and by the survival of some genetic information in modern humans across Asia. Present-day Sherpas, Tibetans and neighbouring populations display Denisovan-derived genetic variants that help them to survive at high altitudes. However, it had been unclear why Denisovans possessed this adaptation, as fossil evidence of the archaic humans has been limited to the Denisova cave, at an altitude of only 700 metres.
Jean-Jacques Hublin, Frido Welker, Dongju Zhang and colleagues describe a hominin jawbone found in Baishiya Karst Cave on the Tibetan Plateau, at an altitude of 3,280 metres. Analyses of ancient proteins from the bone identify it as Denisovan, and radioisotope dating indicates that it is at least 160,000 years old. This age predates the earliest evidence of human presence at this high altitude on the Tibetan Plateau (dated to around 30,000-40,000 years ago). The elevated location of the fossil may explain why Denisovans possessed genetic variants that provide adaptions to high-altitude, low-oxygen environments. The age of the jaw is compatible with the oldest Denisovan fossil currently known from Denisova Cave, and some of its features, such as its dentition, are similar to those of previously described Denisovan fossils.
Together, these findings help us to improve our understanding of hominin evolutionary history in East Asia.