10 May 2010
ByAppeared in BioNews 557
Neanderthals are our closest evolutionary relative, a study published in the journal Science has found. Between one and four per cent of human genes originate from Neanderthals, who interbred with humans many thousands of years ago.
The study used powdered bone retrieved from three Neanderthal females, who died in a cave in Croatia over 40,000 years ago, to nearly 60 per cent sequence the Neanderthal genome. This 'is a very good statistical sample of the entire genome' said Professor Svante Pääbo, from the Max Plank Institute for Evolutionary Anthropology, Germany. The team then compared the Neanderthal genome to the genome of modern humans living today in Europe, the Far East and Africa.
The study suggests that since the genomes from the non-African humans were most similar to the Neanderthal genome, the two species are most likely to have interbred approximately 50,000 to 100,000 years ago in the Middle East, after they left Africa.
The researchers also found that the genomes of modern humans and Neanderthals are 99.5 per cent identical. Professor Richard Green from the University of California Santa Cruz, US, said that the results provide 'compelling' evidence that some interbreeding occurred between the two species.
'The sequencing of Neanderthal genetic material is real gold because we can now compare the Neanderthal genome with our own and pinpoint the genetic changes that have enabled humans to thrive, spread across the entire globe, and to occupy every ecological niche that exists in the world', he said.
His group also reported at least five genes in modern humans may have given us a survival advantage over Neanderthals, including genes involved in mental development, energy metabolism, and in developing parts of the human skeleton.
Some archaeologists, however, remain sceptical. Richard G. Klein, Professor of Anthropological Sciences at Stanford University, says the work: 'contradicts everything we know about the archaeological record. Their evidence is wobbly and it bothers me a lot. But it's very important stuff if it's right - and I really do hope it's right'.
Neanderthals originated in Africa and share a common ancestor with modern humans from at least 400,000 years ago. They are known to have left Africa and spread through the Middle East to populate Europe and Asia, before becoming extinct about 30,000 years ago.
The finding broaches the long-running debate that has split anthropologists for decades: whether modern humans are solely African in origin, or come from interbreeding between early human species and Neanderthals.