An ancient jawbone dredged from the Taiwanese seabed has revealed new insights into the appearance and sweeping geographic range of an enigmatic human species called the Denisovans.
The fossil was discovered by fishers trawling the Penghu Channel off Taiwan and is thought to be the most complete fossil that has been genetically identified as Denisovan. The male individual, who lived at least 10,000 years ago, had a strong jaw and very large, powerful molars.
“From a tooth or a small bone fragment, there’s the mystery of their appearance,” said Prof Enrico Cappellini, of the University of Copenhagen, a co-senior author on the paper. A Denisovan jaw discovered in Tibet had begun to fill in this picture, and the latest discovery adds to the evidence of a prominent jaw with huge teeth.
“Now we have a richer image,” Cappellini said. “Of course it would be good to have a skull and the rest of the skeleton, but it’s a step forward.”
The fossil has been dated to one of two glacial periods when the channel is known to have been above sea level, either between 10,000 and 70,000 years ago or between 130,000 and 190,000 years ago.
The scientists were not able to obtain DNA from the sample but managed to extract proteins, which could be sequenced and used to place the fossil confidently on the Denisovan branch of the evolutionary tree.
The discovery reveals an impressive geographic range for the ancient species, which lived at the same time as – and interbred with – modern humans and Neanderthals.
The first Denisovan fossils, identified through analysis of ancient DNA, came from a cave in Siberia and comprised just a finger fragment and a few teeth. Since then, further discoveries show Denisovans also weathered the incredibly harsh conditions of the high-altitude Tibetan plateau, where temperatures can plunge to -30C. By contrast, in south-east Asia they would have lived alongside water buffaloes in a balmy climate.
“These are climate and environmental conditions that are quite different,” Cappellini said. “The cold environment in Siberia, high altitude in Tibet. We cannot infer anything of their cognitive abilities … but they had an ability to adapt to environments that are quite diverse.”
Prof Chris Stringer, a leader in human origins research at the Natural History Museum in London, who was not involved in the latest research, said the latest discovery also strengthened the case that Denisovans belong to a group called Homo longi, or dragon man, a complete skull of which was unearthed in Harbin in north-east China.
“It’s now apparent that the Denisovans must have had a wider environmental range than the Neanderthals, from cold, open environments in northern Asia to subtropical woodlands in south-east Asia,” he said. “A question for the future will be whether we end up calling Homo longi Denisovan or we end up calling Denisovans Homo longi.”
The findings are published in the journal Science.
