Fleshing out the past: ancient Chinese skulls offer strong evidence that Neanderthals reached East Asia
Researchers believe the species may have bred with local humans
Scientists have uncovered strong evidence in central China that Neanderthals reached East Asia and interbred with the hominid population there roughly 100,000 years ago.
The discovery through computer analysis of two skulls expands the range of the archaic humans, suggests modern Chinese might have a European ancestor and challenges the idea that Neanderthals struggled to mix with local populations.
The research on the human skulls unearthed in Xuchang, Henan province, by Chinese and US scientists was published on Friday in the journal Science.
Neanderthals were a muscular, early human species with large brains and were well adapted to the cold. Their bulk helped them survive and thrive through numerous ice ages until they suddenly died out about 40,000 years ago.
At first their remains were found only in Western Europe, but Neanderthal finds have since been reported in Africa, Eastern Europe, Central Asia and Siberia. The Xuchang skulls expand that range to East Asia.
When the researchers examined the skulls, they found a bony, labyrinthine structure that housed the inner-ear nerves essential for hearing and balance.The delicate structure of this organ varies from one species to another and is a useful way to identify early humans.
The Xuchang Man’s bone labyrinth matched to those found in Neanderthals, according to CT scans.
Researchers also identified a tiny, triangular-shaped dent on the back of the skulls – a dent found on no other human species except Neanderthals.
“We have found so far the strongest evidence of Neanderthals in East Asia and this is a very exciting,” said Professor Wu Xiujie, a lead scientist of the study with the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing.
“From these skulls came to light lots of important information that tells us not only where Chinese come from but an entire missing chapter in human evolution history.”
Previous finds in other sites such as Xujiayao and Maba also reported Neanderthal-like traits but none were as distinctive and conclusive as those from Xuchang, Wu said.
The Neanderthals disappeared in about the same time as modern humans walked out of Africa and spread around the globe. One theory is that Neanderthals in Europe and Asia were wiped out by the newcomers. Molecular science supported that theory because most people living today owe most of their DNA to the small group of people first out of Africa.
But further analysis of ancient DNA samples from Neanderthal bones found their genes had been passed down to modern Europeans, albeit in trace amounts. This led some researchers to suspect the history of human evolution might not be as simple as one species replacing the other.
The Xuchang skulls show strong signs of genetic exchange among different human species, suggesting
Xuchang was an evolutionary melting pot of early humans of European, African and local origins living together and intermingling, Wu said.
“It is possible the genes of the Xuchang people flow in our blood,” she said.
Erik Trinkaus, another lead scientist of the study and professor of anthropology at Washington University in St Louis, said the Xuchang skulls substantially increased understanding of the biological nature of the immediate predecessors of modern humans in eastern Eurasia.
“The features of these fossils reinforce a pattern of regional population continuity in eastern Eurasia, combined with shared long-term trends in human biology and populational connections across Eurasia. They reinforce the unity and dynamic nature of human evolution leading up to modern human emergence,” Trinkaus said.
Professor Su Bing, researcher on human evolution with Kunming Institute of Zoology under the Chinese Academy of Sciences, said the Xuchang skulls were an important and interesting discovery but the singular samples could not challenge the overwhelming DNA evidence of massive replacement of local people by migrants from Africa.
“Millions of genetic samples from people living today all point to an African origin. The Neanderthals might have contributed one or two per cent to our genes, but the rest all came from Africa,” Su said.
“The Xuchang skulls might represent a case of genetic exchange, but it may be just an accident, with little change to the overall trend of human evolution.”