Story of human evolution gets another rewrite with DNA analysis of Chinese teeth

Fuyan cave in Daoxian County, Hunan province, China, is shown here. Scientists have dated teeth found inside the cave that suggest modern humans arrived in China less than 50,000 years ago.

(CNN)Experts hailed the discovery in 2015 as "stunning" -- 47 teeth found in a cave in southern China dated back to 80,0000 to 120,000 years ago, challenging widely accepted ideas about human evolution.

It suggested that Homo sapiens were in China at least 20,000 years earlier than early modern humans had been previously believed to have left Africa and spread around the world. It also tantalizingly hinted at the possibility that a different group of early humans could have evolved separately in Asia.
Not so fast, says the science in 2021. New research published Monday has suggested perhaps we shouldn't be so eager to rewrite the time line on human origins.
    DNA analysis of two human teeth found in the same cave, called Fuyan, plus teeth and other fossilized remains from four other caves in the same region, suggested that it was unlikely early modern humans were in China so early.
      This is the entrance to Fuyan Cave.
      "Our new research means it is very unlikely that Homo sapiens reached China before 50,000 years ago. It is always possible that our species reached the region more than 100,000 years ago, but we would have to say that there is no convincing evidence in favor of this at present," said Darren Curnoe, an associate professor at the Australian Museum Research Institute in Sydney and coauthor of the paper that published in the journal PNAS 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 range of different 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 which determined the age of cave materials (flowstone) lying above and below the sediments containing the human teeth," he said via email. Flowstone is a sheetlike deposit of rock formed by flowing water.
          "It is well understood that the most reliable dates come directly from the materials of interest to archaeologists, in this case, the human teeth. Our new (dates), including direct ages, are far younger than previously suggested."
          The 2015 study measured the radioactive decay of uranium within 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 had always stood out and it was right to investigate them further using different methods.
          However, he said the study, while interesting, didn't definitively rule out early modern humans in China before 50,000 years ago.

          Complex family tree

          Untangling human ancestry is a complicated business, and recent research has indicated the human family tree is much more bushy and less linear than the traditional "Out of Africa" narrative, which suggested 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 hominins existed and coexisted before Homo sapiens emerged as the lone survivor, and there was interbreeding between different groups of early humans.
          Some of these groups -- like Neanderthals -- are easily identified through the fossil record and archaeological remains, but others -- like the Denisovans -- have been largely identified by their genetic legacy.
          Maria Martinón-To