The unearthing of a thigh bone fragment dated to be around 14,000 years old in a Southwestern Chinese cave has led researchers to believe that a human species which was supposed to be extinct a long time ago survived till about that time.
On comparison with modern human leg bone, the bone fragment was found to be similar to a particular species of humans who were thought to have vanished by the Late Pleistocene age. This age is a time-frame from the Pleistocene period, which lasted from about 2,588,000 to 11,700 years ago.
Though Homo sapiens is the only remaining human species on earth, in ancient times, they shared the earth with other human species such as the Neanderthals, Homo erectus, Homo habilis, and the Denisovans.
Some of these species intermingled with the Homo sapiens, as was seen in the presence of Denisovan genes in modern humans.
Associate Professor Darren Curnoe from the University of New South Wales, Australia, and Professor Ji Xueping from the Yunnan Institute of Cultural Relics and Archaeology, China, jointly led the team which made the discovery.
The 14,000-year-old bone fragment, which was found among the remains of the 'Red Deer Cave people' of China, despite being relatively 'young', shows certain characteristics similar to the most ancient members of the 'Homo' human genus. Thus, it can be derived that a particular human species other than the Homo sapiens survived till at least the last Ice Age.
"Until now, it was thought that archaic humans on mainland Asia had survived no later than around 100,000 years ago. So, to find a human bone that resembles very ancient humans that is only around 14,000 years old is a real surprise", said Curnoe, also the lead author of the study, in an email to CS Monitor.
"Now, it is only one bone, so we need to be a bit careful," added Curnoe. But if the bone fragment does represent ancient humans, it suggests that "there must also have been overlap in time between archaic and modern humans for tens of thousands of years in Southwest China."
"We published our findings on the skull bones first because we thought they'd be the most revealing, but we were amazed by our studies of the thigh bone, which showed it to be much more primitive than the skulls seem to be," said Professor Ji.
"The unique environment and climate of southwest China resulting from the uplift of the Tibetan Plateau may have provided a refuge for human diversity, perhaps with pre-modern groups surviving very late," Ji added.
According to genomic research, it was the contemporary East Asians who got more DNA hand-downs from the Neanderthals, than the Europeans. The Neanderthals, who died out around 40,000 years ago, are said to have inhabited Southern and Western Europe, certain areas of Central and Northern Asia and the Middle East. This indicates that there must have been many interbreeding episodes, in various demographic scenarios covering a wide geographic area.