The oldest man in China yields up his secrets

Twelve years ago on a summer afternoon, local farmer Tian Xiumei climbed a mountain in Fangshan district, 50 kilometres southwest of Beijing, in search of water to irrigate her trees. Halfway up, she found a small cave that looked like the mouth of a spring. Tian took a flashlight and dove into a narrow entrance only just wide enough to fit through. She was disappointed to find no traces of a spring.

What she discovered instead were fragments of bones. Scientists from China’s Institute of Vertebrate Paleontology and Paleoanthropology  (IVPP) were called in, and their excavations on the same spot revealed a partial human skeleton – the remains of an early ancestor of modern Chinese.

On January 21 of this year, the scientists released their latest research findings on the bones excavated from Tianyuan Cave. The ancient DNA has revealed that humans who lived some 40,000 years ago in the area near present-day Beijing were likely related to present-day Asians and Native Americans.

The scientists sequenced nuclear and mitochondrial DNA that was extracted from the leg of the Tianyuan Cave man, who lived about 40,000 years ago.

Previous DNA evidence on modern man in East Asia could only be traced back to less than 10,000 years ago.

“This individual lived during an important evolutionary transition when early modern humans, who shared certain features with earlier forms such as Neanderthals, were replacing Neanderthals and Denisovans, who later became extinct,” says Svante Paabo from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Paabo is the leader of the study, jointly conducted by the Max Planck Institute and the IVPP.

Gao Xing, deputy director of the IVPP, says: “This is the first time that Chinese paleoanthropologists have extracted DNA from ancient humans who lived more than 10,000 years ago.”

Previously, the only evidence scientists in China had of early modern humans was fossils and cultural remains.

“Traditionally, we infer by observing the fossils and tools on the site, but molecular biology has opened a new door for us,” Gao explains.

“For example, based on isotope analysis of carbon, nitrogen and oxygen, we found that the Tianyuan Cave man ate freshwater fish, which we had no way to find out from studying fossil morphology, and there is no tool left in the cave for such analysis.”

But buried in the cave for tens of thousands of years, most DNA contained in the bone had been destroyed. Bacterial contamination has made it even more difficult to extract the DNA.

“Only 0.3 to 0.4 per cent of the DNA belonged to humans. The rest was bacteria,” says Fu Qiaomei, primary author of the research paper.

“Finding the human DNA was like looking for a needle in a haystack. It needed strong technical support,” Fu says.

The Max Planck Institute, as the industry leader in this field, provided technical support for the research.

“China has abundant research materials for paleoanthropologists, and that’s a major reason that foreign institutes are attracted to China,” says IVPP deputy director Gao Xing.

He says that now paleoanthropologists are quite certain about the human evolutionary pathway in Africa and Europe, but there is still a research gap in East Asia.

“East Asia and Africa are the two most promising regions for paleoanthropology research, and the jigsaw will not be completed without figuring out the situation in China.”

As for the theories of the origins of modern human beings, there are two popular explanations: one is that modern humans are descendants of regional archaic-type human groups in Africa and Eurasia about 40,000 to 50,000 years ago; the other is that modern humans thrived about 200,000 years ago in Africa and later migrated elsewhere.

Gao says the latest breakthrough shows that 40,000 years ago, Asians and Native Americans were still related by blood, but their DNA had divided since the time of modern Europeans. Those discoveries are still not enough to give a full picture of human evolution.