By a Newsnet reporter
The science journal PLoS ONE has published a paper describing the discovery in southern China of the fossilised remains of what may be an entirely new species of ancient humans.
Dubbed the "Red Deer People", the bones were discovered in association with red deer remains which apparently formed the basis of their diet. The remains date to between 11,000 and 14,000 years ago.
The dating places the fossils amongst the most recent non-modern human remains ever to have been discovered, and means that modern humans were sharing the planet with non-human species of hominin until shortly before the development of agriculture.
Bearing a mixture of ancient and modern features, the inhabitants of the caves in the Chinese provinces of Guanxi and Yunnan were apparently isolated from more modern populations surrounding them. An artist's impression of a Red Deer man is shown above.
The distinctive skull of an individual from the "Red Deer People" was unearthed in 1979 in Longlin cave in Guangxi Province in the south of China, but has only now been fully analysed. Remains of at least three other "red deer people" were found at Maludong near the city of Mengzi in Yunnan Province in 1989.
The skulls have thick bones, and are characterised by prominent brow ridges, a short flat face and the lack of the distinctively modern human chin. The Red Deer People had brains about the same size as modern humans.
Professor Darren Curnoe, of the University of New South Wales, co-leader of the research team studying the remains, said the physical appearance of these extinct people was unique amongst all members of the human evolutionary tree.
''They look very different to all modern humans, whether alive today or in Africa 150,000 years ago," he said.
Professor Curnoe said one possibility was that they were modern humans who left Africa very early on and reached China, but then did not contribute genetically to people alive in East Asia today. However he believes it more likely that they represent a previously unknown species of human. ''While finely balanced, I think the evidence is slightly weighted towards the Red Deer Cave people representing a new evolutionary line,'' Professor Curnoe said.
The last decade has witnessed an explosion of scientific discoveries which have radically rewritten understanding of the human past. It is now known that all modern human populations descend from a relatively small group which evolved in Africa around 160,000 years ago before spreading out across the globe. As they did so they encountered earlier populations of humans who descended from earlier migrations of pre-modern human ancestors out of Africa.
Neanderthals are believed to have died out some 25,000 years ago. The last Neanderthal populations apparently lived in parts of Europe until they were replaced by modern humans migrating in from Asia. Recently the Neanderthal genome was decoded, proving that they represented a different species of humanity from modern humans. The DNA analysis also showed that Neanderthals made a tiny contribution to the genes of modern Europeans, meaning that there was at least some limited interbreeding between the Neanderthals and modern humans.
Remains of a dwarf population of ancient humans, Homo floresiensis, popularly called 'the Hobbit', were discovered on the Indonesian island of Flores in 2003. The Hobbit may have survived until as recently as 12,000 years ago when a massive volcanic eruption devastated the island.
Eight years ago, fragments of DNA were successfully extracted from a fossil human finger bone discovered in the Denisovan caves in Siberia. Dating to around 30,000 years ago, the DNA sample was found to come from a different species of human from any other known previously. The Denisovan species is the only human species to have been identified solely from DNA evidence.
According to the New Scientist magazine, the Red Deer People, the Hobbit, Neanderthals and the Denisovans might not have been the only ancient humans to survive until relatively recent times. Human skeletons just 8000 years old with unusually archaic features have been discovered in south Asia and India but have not yet been fully analysed. With further study, some of these remains may prove to represent different species of humans who still survived after modern humans developed agriculture.