Ancient human DNA claim dismissed

2019-03-06 04:20:26

By Emma Young Claims by two researchers that they have isolated DNA from a 1.8 million-year-old hominid have been dismissed by leading palaeoarchaeologists. Tom Loy of the University of Queensland, Australia, and Bonnie Williamson of Witwatersrand University, South Africa, are reported to have found a minute sample of blood on an ancient stone tool from South Africa’s famous Sterkfontein valley. They isolated DNA from that sample and sequenced it. “The DNA we have found is something between a chimpanzee and a human, which suggests a hominid,” Williamson told Johannesburg’s Mail & Guardian newspaper. However, Alan Cooper of the Ancient Biomolecules Centre in Oxford, UK, says it is much more likely to be blood from a modern-day archaeologist. “This is yet another ancient DNA claim that is totally lacking in experimental and intellectual rigour,” Cooper told New Scientist. “Everything we know about ancient DNA tells us that it can’t be correct.” Chris Stringer, a palaeontologist at the Natural History Museum in London, agrees: “I do not believe that DNA of that age could be that well preserved.” The oldest sample of DNA successfully isolated to date was about 50,000 years old, and came from a deep frozen mammoth. Most researchers think the theoretical limit for extraction is about 100,000 years old. After this time, DNA becomes too degraded to study. Cooper says the results of the DNA sequencing of the blood sample could have a simple explanation. “If it’s human DNA left by some archaeologist and it’s been there for 10 or 15 years, inevitably you would get damage to DNA sites from oxidation, UV light, and so on. So the sequence that you get back wouldn’t be quite human.” Previous claims by other researchers that they have obtained such ancient DNA have all been proved false. Loy and Williamson were uncontactable on Tuesday,