The first comparison of human and Neanderthal DNA shows that the two lineages diverged about 400,000 years ago and that Neanderthals may have had more DNA in common with chimps than with modern humans.
There is ongoing debate over whether the Neanderthals were a separate species, Homo neanderthalensis, or a subspecies of Homo sapiens. The first Neanderthals are thought to have emerged about 350,000 years ago, so the new findings from this DNA analysis strongly favour the theory that modern humans and Neanderthals share a common ancestor but are not more closely related than that.
Genetic analysis of Neanderthals is very tricky because mere fragments of nuclear DNA have been recoverable from fossils. Previous analyses have focused on mitochondrial DNA samples, which survive better.
James Noonan at Lawrence Berkeley National Laboratory in California, US, and colleagues compared human, chimpanzee and Neanderthal nuclear DNA samples. The newly compiled DNA dataset was derived from the remains of a 45,000-year-old Neanderthal fossil.
From the enriched dataset, the researchers calculated that humans and Neanderthals diverged approximately 400,000 years ago. And the new data promise to reveal more about the genetic basis of differences between humans and Neanderthals – differences that presumably resulted in the success of modern humans as a species – the researchers say.
“This is a hint of exciting things to come as more Neanderthal sequence is produced,” says David Haussler at the University of California, Santa Cruz, US.
The researchers say the findings strengthen the argument that Neanderthals did not contribute substantially to the modern human genome. “Were there Neanderthals in our lineage? All of the genetics seems to be going in the direction that there weren’t,” says Richard Potts, head of the Smithsonian Institution’s Human Origins Program in Washington DC, US.
Noonan will present the findings at the American Society of Human Genetics conference in New Orleans, US, this week.
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