He suggested that Homo sapiens was in China at least 20,000 years earlier than the first modern humans were believed to have left Africa and spread across the world. It also tantalizingly suggested the possibility that a different group of primitive humans might have evolved separately in Asia.
Not so fast, science says in 2021. New research published on Monday suggested that perhaps we shouldn’t be so eager to rewrite the timeline on human origins.
DNA analysis of two human teeth found in the same cave, called Fuyan, as well as teeth and other fossilized remains from four other caves in the same region, suggested that the first modern humans were unlikely to be in China anytime soon.
“Our new research means that it is very unlikely that Homo sapiens arrived in China before 50,000 years ago. It is always possible that our species arrived in the region more than 100,000 years ago, but we would have to say that there is no convincing evidence in favor of that at the moment, “said Darren Curnoe, associate professor at the Australian Museum Research Institute in Sydney and co-author of the article published in PNAS magazine on Monday.
The researchers were able to extract DNA from 10 human teeth and establish the age of other materials in the caves, such as charcoal and animal teeth, using a variety of methods. The team found that the teeth were at least 16,000 years old, while the other materials were less than 40,000 years old.
“The 2015 study relied heavily on the results of a single dating method that determined the age of the cave materials (fluid stone) above and below the sediments containing human teeth,” he said by email. Flowstone is a leaf-shaped rock deposit formed by running water.
“It is well understood that the most reliable dates come directly from materials of interest to archaeologists, in this case, human teeth. Our new (dates), including direct ages, are much younger than previously suggested.”
The 2015 study measured the radioactive decomposition of uranium in cave deposits, not DNA.
Chris Stringer, research leader for human evolution at the Natural History Museum in London, said that the dates of Chinese fossilized teeth always stood out and that it was right to investigate them further using different methods.
However, he said the study, while interesting, did not definitively exclude the first modern humans in China before 50,000 years ago.
Complex family tree
Untangling human ancestry is a complicated business, and recent research has indicated that the human family tree is much thicker and less linear than the traditional “Out of Africa” narrative, which suggested that modern humans originated in Africa and made their first successful migration to the rest of the world in a single wave between 50,000 and 70,000 years ago.
Many different ancient hominids existed and coexisted before Homo sapiens emerged as the only survivor, and there was a cross between different groups of primitive humans.
Some of these groups – such as Neanderthals – are easily identified through fossil record and archaeological remains, but others – such as Denisovans – have been widely identified for their genetic legacy.
Maria Martinón-Torres, director of the National Research Center for Human Evolution in Spain and author of the 2015 study, said she welcomed the new data on the early presence of modern humans in China.
However, she noted that the two teeth of the Fuyan cave were discovered in 2019 and did not belong to the original sample that her team studied and published in 2015.
“Accurate data on the location and morphology of the sample is crucial, but it is not provided on paper,” she said.
“I agree that we must work to improve the dates for all places of interest, especially with direct dating when possible. However, at the moment, there is an increasing number of samples that would support the presence of H. sapiens outside Africa before 50 ka (50,000 years ago), “she said by email.
She noted that there are other discoveries in Saudi Arabia, Israel, Sumatra and Laos, and another location in China where a jawbone was found, which supports the presence of Homo sapiens outside Africa before 50,000 years ago.
One of the main factors supporting the idea that the first modern humans left Africa about 50,000 years ago is that there is a strong signal in the genes of today’s human populations.
“We would say that Out of Africa after 70,000 years ago seems to be the dominant image. We cannot prevent earlier dispersions in other regions, but certainly southern China seems to have been colonized in this wave of Out of Africa after 50,000 years ago,” Curnoe said by email.
However, Martinón-Torres said that this does not rule out the possibility that previous groups of Homo sapiens have roamed Asia before – just as groups of other primitive humans like Neanderthals and Denisovans did.
“We had no expectations about the dating of these fossils and sites and we would have been satisfied if we had confirmed an early dispersion. This would certainly have made the history of our species much older than was generally believed, and perhaps more interesting,” said Curnoe.
“Unfortunately, this does not seem to be the case, at least in southern China, according to our work.”