Fossils discovered in south-west China may represent a new species of human, living as recently as 11,500 years ago.
The fossils display an unusual mix of archaic and modern anatomical features, and are the youngest of their kind ever found in mainland East Asia, at just 14,500 to 11,500 years old.
They would have lived alongside modern-looking people at a time when China's earliest farming cultures were beginning. They've been dubbed the Rded Deer People, on the basis of their diet.
"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," says Professor Darren Curnoe of the University of New South Wales.
"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."
The remains of at least three individuals were found by Chinese archaeologists at Maludong - also known as Red Deer Cave - in Yunnan Province during 1989. They remained unstudied until 2008.
A Chinese geologist found a fourth partial skeleton in 1979 in a cave in neighbouring Guangxi Zhuang Autonomous Region - but that stayed encased in a block of rock until 2009 when the international team removed and reconstructed the fossils.
Until now, no human fossils younger than 100,000 years old have been found mainland East Asia, apart from Homo sapiens, implying that the first modern humans colonized an empty landscape.
The new discovery suggests this might not have been the case after all.
"Because of the geographical diversity caused by the Qinghai-Tibet plateau, south-west China is well known as a biodiversity hotspot and for its great cultural diversity. That diversity extends well back in time" says Professor Ji Xueping of the Yunnan Institute of Cultural Relics and Archeology.
Over the last ten years, evidence has emerged in Asia challenging accepted views of human evolution, including fossils of the 17,000-year-old Indonesian Homo floresiensis, and evidence for modern human interbreeding with the ancient Denisovans from Siberia.
"The discovery of the red-deer people opens the next chapter in the human evolutionary story – the Asian chapter – and it's a story that's just beginning to be told," says Professor Curnoe.