Ancient DNA Discovered…Or Not

Researchers in South Africa claim they have extracted the DNA of an early human.

The microscopic traces of blood which yielded the sample are apparently from a 1.8 million-year-old hominid. If the claim is authenticated the DNA will be the oldest sample ever extracted.

Wits University micro-archaeologist Bonnie Williamson, says, ?The DNA we have found is something between a chimpanzee and a human, which suggests a hominid.? Williamson and her colleague Professor Tom Loy of the University of Queensland believe this DNA sequence is from either our direct ancestor Homo habilis or Paranthropus robustus. The tools on which the blood was found were in the Sterkfontein Caves, a World Heritage site in the Gauteng region.

Professor Loy says, ?We strongly suspect that the DNA that we have is that of a hominid, but we still want to conduct more research to verify our claim.? In 1995 similar claims about an 80-million-year-old dinosaur bone were dismissed by other researchers who concluded the DNA belonged to a mammal.

These claims have been dismissed by other palaeoarchaeologists. Alan Cooper of the Ancient Biomolecules Center 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 rigor,? he says. ?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,? he says.

The oldest sample of DNA successfully isolated to date is 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 say they plan more research to verify their study.

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