OUR CLOSEST extinct relatives, the Neanderthals, have come to life in a remarkable way with the announcement that scientists have captured a first draft of their genetic code.
There is no question of cloning these early humans who disappeared about 30,000 years ago but researchers will now be able to conduct direct genetic comparisons between Neanderthals and modern humans.
The startling achievement was announced yesterday at the American Association for the Advancement of Science annual meeting, taking place in Chicago. Details of the work were revealed by lead scientist Prof Svante Pääbo, of the Max Planck Institute for Evolutionary Anthropology, who said the team’s first draft of the Neanderthal genome includes more than three billion DNA steps and represents almost two-thirds of the complete genetic blueprint.
Modern humans and Neanderthals shared a common genetic ancestor about 300,000 years ago, he said.
At that time a new species emerged, Homo sapiens, a species that went on to spread out of Africa about 50,000 years ago and displace all other human-like species including the unfortunate Neanderthals.
The work had been a huge technological challenge because of the difficulty in extracting DNA from ancient bones and ensuring that it was not contaminated with genetic material from bacteria, fungi or indeed DNA from the scientists themselves, Prof Pääbo said.
They now believe that the genetic sequences they have contain no more than a 1 per cent level of genetic contamination.
It was also a challenge because there was so little material to work from.
They studied about 70 Neanderthal bone fragments dug out of 16 sites across Europe and Eurasia.
Each sample might only yield a few per cent of the full genome, but when added together and screened to ensure it was true Neanderthal DNA, a patchwork quilt of their genetic blueprint was assembled.
Even this incomplete draft, which is added to as the work progresses, was hugely important and valuable as a tool to study links between us and our ancient cousins.
It allowed scientists to understand when the two species diverged and provides tantalising insights as to what helped Homo sapiens to survive. “We can start looking at interesting genes,” he said.
Early analysis has shown that Neanderthals possessed a gene, Foxp2, that has a known association with language ability in humans. Genome comparisons with our next closest ancestors, the chimps, shows they do not possess the Foxp2 gene, Prof Pääbo said.
“There is no reason to assume they [Neanderthals] could not articulate the way we do,” although its presence in the genome does not confirm they spoke. The team, which includes scientists from Croatia, Spain and Russia, has also looked at a gene that allows us to drink milk as adults.
Only a small number of humans lack this gene, making them lactose intolerant, but on the basis of the study this was not the case with the Neanderthals, Prof Pääbo said. “The Neanderthal was not able to drink milk after he was weaned.”
Prof Pääbo could foresee no time when a Neanderthal could be cloned from its genome, but the work did show that humans and Neanderthals did not interbreed.
This was achieved by looking for Neanderthal DNA in modern humans. “If there was a contribution it was very small. It was tiny,” he said.