The team’s discovery three years ago, detailed in a paper in the journal Acta Anthropologica Sinicaearlier this year, added a new piece to the puzzle of Chinese origins but not the full picture, in the absence of DNA analysis.

Over the past decade, ancient human fossils have been found in almost every province in southern China, many of them from sediments dating back 100,000 years or more but with anatomical features little different to the Chinese people living today.

However, analysis of the evolutionary history of the male Y chromosome has traced the origin of all Chinese men to an “Adam” from Africa who arrived in Southeast Asia about 60,000 years ago. The thinking has been that when he and his sons moved north to what is now China, they either encountered a zone devoid of others humans or killed all they found, otherwise the modern Chinese man would have more than one father among his ancestral roots.

“It is quite clear now that the first hypothesis [that there were no humans present] was incorrect,” said Professor Liu Wu, from the Chinese Academy of Sciences’ Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing.

A colleague of Zhao, Liu found equally old human fossils in Daoxian, Hunan. The discovery of Daoxian Man, first published in the journal Nature last year, suggested that those living in China more than 100,000 years ago were exactly the same as modern human beings.

“There is overwhelming evidence from fossil records that China was populated with humans before the arrival of African settlers,” Liu said. “They don’t live in one or two small areas, but thriving, almost everywhere.”

If so, were they driven to extinction by the new boys in town?

“I don’t think so,” Liu said.

In a paper in the same issue of Acta Anthropologica Sinica, renowned palaeoanthropologist Wu Xinzhi reported that a thorough examination of the stone tools made by ancient people in China from 130,000 to 8,000 years ago had concluded that the manufacturing techniques had been passed down with consistency from one generation to another, and with features distinct from the stone tools made by the early African migrants.

The stone tool cultures, as well as the large volume of ancient human fossils unearthed in China, suggested the modern day Chinese was the result of a seamless evolution in the region. Though the arrival of the African migrants might have introduced some new genes, no replacement or massive extinction had happened, according to Wu and colleagues.

To find the truth, the DNA in the ancient remains could be compared with those of modern Chinese. Similar work has been done in Germany on the fossil of Neanderthals, who lived in Europe before the arrival of the African migrants, with the results showing that present day Europeans all carried some Neanderthal genes, which suggested the arrivals had mingled with the locals rather than exterminating them.

But repeating the experiment in China would be more difficult because the Chinese samples are much older than those of the Neanderthals, who lived as recently as 28,000 years ago. The older the remains, the less DNA information is preserved and the higher the chance that the researchers would find nothing at all.

“We must assess the risk because any DNA analysis will inevitably cause irreversible destruction to a piece of precious fossil,” Liu said. “We will only conduct the test when the benefit far exceeds the cost.”

Professor Li Hui, who studies ancient human DNA at Fudan University in Shanghai, said today’s technology made him confident that useful DNA fragments could be extracted from samples 100,000 years of age or older.

“Any sample that can be carbon-dated can be used for DNA analysis,” he said. “We have the most cutting-edge technology to do the job.”

Li said that for a DNA test, researchers would need to grind an entire tooth down to a fine powder, or do the same thing with a piece of skull as large as a finger nail.

From a molecular scientists’ point of view, it was “almost a fact” that all Chinese men were descended from an African father, Li said. Although fossils remains were important evidence they were less reliable than DNA testing because the sediment layer where they were buried could have been disturbed by recent geological activity, giving dating results that might exaggerate the fossil’s age.

About 75,000 years ago, a super volcano in Indonesia erupted and caused global cooling which led to a famous extinction event, known as the Toba catastrophe, which turned the earth to a snow ball for more than 1,000 years and wiped out a large number of species, including some early humans.

It was possible that a small number of humans survived the catastrophe, Li said, but they would have been unable to resist the new arrivals from Africa, and even if they mingled, the contribution of the native DNA in modern Chinese would be extremely small, unlikely to exceed 2 per cent.

“We’d very much like to test some extremely old samples, but we can’t access any,” he said.

“The disagreement [on the origin of Chinese] can only be solved by a collaboration agreement between those who own the fossils and those who own the [ancient DNA analysis] technology.”