Fossils of what could be a previously unknown type of human have been found in caves in southern China.
According to Darren Curnoe, a palaeoanthropologist at the University of New South Wales in Australia, "These new fossils might be of a previously unknown species, one that survived until the very end of the ice age around 11,000 years ago...Alternatively, they might represent a very early and previously unknown migration of modern humans out of Africa, a population who may not have contributed genetically to living people."
According to Charles Choi of LiveScience:
The Stone Age fossils are unusual mosaics of modern and archaic human anatomical features, as well as previously unseen characteristics. This makes them difficult to classify as either a new species or an unusual type of modern human.
For instance, the Red Deer Cave people had long, broad and tall frontal lobes like modern humans. These brain lobes are located immediately behind the forehead, and are linked with personality and behavior.
However, the Red Deer Cave people differ from modern Homo sapiens in their prominent brow ridges, thick skull bones, flat upper faces with a broad nose, jutting jaws that lack a humanlike chin, brains moderate in size by ice age human standards, large molar teeth, and primitively short parietal lobes -- brain lobes at the top of the head associated with sensory data. 'These are primitive features seen in our ancestors hundreds of thousands of years ago,' Curnoe said.
Unique features of the Red Deer Cave people seen neither in modern nor known archaic lineages of humans include a strongly curved forehead bone, very broad nose and eye sockets, and very flat cheeks that flare widely to the sides to make space for large chewing muscles. In addition, the place where the lower jaw forms a joint with the base of the skull is unusually wide and deep.
All in all, the Red Deer Cave people are the youngest population to be found anywhere in the world whose anatomy does not comfortably fit within the range of modern humans, whether they be modern humans from 150 or 150,000 years ago, the researchers noted.
'In short, they're anatomically unique among all members of the human evolutionary tree,' Curnoe told LiveScience.
The people, which are being called "Red Deer Cave" people after where they were found, and what they preferred to eat, lived in China at the end of the last Ice Age. They even "shared the landscape" with early pre-farming communities, but it is unknown how exactly they interacted.
However, there is still some disagreement surrounding their categorization:
A key reason the scientists have not yet decided how to classify the Red Deer People scientifically has to do with one of the major ongoing questions for scientists investigating human evolution -- 'the lack of a satisfactory biological definition of our own species, Homo sapiens,' Curnoe said. 'We still don't have one that most of us agree upon.'
'I think the evidence is slightly weighted towards the Red Deer Cave people representing a new evolutionary line,' Curnoe said. 'First, their skulls are anatomically unique -- they look very different to all modern humans, whether alive today or in Africa 150,000 years ago. And second, the very fact they persisted until almost 11,000 years ago when we know that very modern-looking people lived at the same time immediately to the east and south suggests they must have been isolated from them. We might infer from this isolation that they either didn't interbreed or did so in a limited way.'
[...] Ultimately, to see how closely or distantly related the Red Deer Cave people are to modern humans or even the Denisovans, the scientists want to extract and test DNA from the fossils. 'We've had one attempt already, but without success,' Curnoe said. 'We'll just have to wait and see if we're successful in our future work.'