DNA extracted from a 29,000-year-old bone has cast doubt on the theory that modern humans evolved in part from squat, heavy-browed Neanderthals, Scottish researchers report in today's Nature. A team from the University of Glasgow compared DNA from a Neanderthal skeleton found in Russia to an older sample tested in 1997. Although the two Neanderthal samples turned out to be just 3.5% different from one another--about the same difference found between two humans--they were roughly 7% different from DNA in modern humans. Scientists consider that to be a substantial gap.
The researchers challenge the theory that modern humans evolved at least partly from Neanderthals, which some believe mated in large numbers with modern Europeans before disappearing 25,000 years ago. If that had happened, some argue, today's Europeans would show stronger genetic similarities to Neanderthals than other humans do. Yet the latest DNA analysis shows Neanderthal DNA to be no closer to that of Europeans than to that of other modern humans.