The fossilised remains of stone age people recovered from two caves in south west China may belong to a new species of human that survived until around the dawn of agriculture.
The partial skulls and other bone fragments, which are from at least four individuals and are between 14,300 and 11,500 years old, have an extraordinary mix of primitive and modern anatomical features that stunned the researchers who found them.
Named the Red Deer Cave people, after their apparent penchant for home-cooked venison, they are the most recent human remains found anywhere in the world that do not closely resemble modern humans.
The individuals differ from modern humans in their jutting jaws, large molar teeth, prominent brows, thick skulls, flat faces and broad noses. Their brains were of average size by ice age standards.
"They could be a new evolutionary line or a previously unknown modern human population that arrived early from Africa and failed to contribute genetically to living east Asians," said Darren Curnoe, who led the research team at the University of New South Wales in Australia.
"While finely balanced, I think the evidence is slightly weighted towards the Red Deer Cave people representing a new evolutionary line. First, their skulls are anatomically unique. They look very different to all modern humans, whether alive today or in Africa 150,000 years ago," Curnoe told the Guardian.
One partial skeleton, with much of the skull and teeth, and some rib and limb bones, was recovered from Longlin cave in Guangxi province. More than 30 bones were unearthed at nearby Maludong, or Red Deer Cave, near Mengzi.