New Methods Let Scientists Analyze Neanderthal DNA
Thursday, November 16, 2006
Unleashing a new kind of DNA analyzer on a 38,000-year-old fragment of fossilized Neanderthal bone, scientists have reconstructed a portion of that creature's genetic code -- a technological tour de force that has researchers convinced they will soon know the entire DNA sequence of the closest cousin humans ever had.
Such a feat, deemed impossible even a few years ago, could tell a lot about what Neanderthals were like, such as their hair and skin color and their relative facility with language, according to scientists in Germany and California who released the new results yesterday. It could also clear up what sort of relationship existed between Neanderthals and the first modern humans -- including whether the two interbred after their evolutionary trajectories diverged.
Most tantalizing, the newfound ability to reconstruct prehistoric DNA allows scientists to home in on the fraction of a percent of human DNA that will differ from that of Neanderthals, who went extinct 30,000 years ago.
Those differences, scientists said, will amount to biological snapshots of what makes humans human.
The new findings that significant amounts of Neanderthal DNA can be retrieved and read "are perhaps the most significant contributions published in this field since the discovery of Neanderthals 150 years ago," David Lambert and Craig Millar wrote in a commentary in the journal Nature, which with the journal Science is publishing the work this week.
Lambert and Millar, who were not involved in the work, are experts in molecular evolution at universities in New Zealand.
"Personally, I was blown away when I first heard wind of this," said Sean B. Carroll, a Howard Hughes Medical Institute investigator and evolutionary geneticist at the University of Wisconsin at Madison. "We're all kind of giddy with excitement."
As the most closely related and most recently departed members of the human family tree -- and as the bony-browed icons of a stonier age -- Neanderthals have long fascinated scientists and armchair anthropologists alike. They and human forebears started as equals hundreds of thousands of years ago but took very different paths.
One line went on to develop haute couture, rock 'n' roll and DNA synthesizers. The other disappeared in a wave that began in Asia about 45,000 years ago and ended with extinction in Europe 15,000 years later.
Some say climate change did them in. Some blame modern humans, who were spreading through Europe at the time and who, perhaps because of some fortuitous genetic mutations, were experiencing an intellectual and cultural awakening.
The quest to understand Neanderthal genetics was for a long time seen as hopeless because DNA, the instructions for life ensconced in cells, breaks down over time.
A few researchers, most notably Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, had extracted DNA fragments from 5,000-year-old mummies and a few older bones, and even stitched a few pieces together in sequence. But the DNA bits from Neanderthals are so old and small that nothing has been able to fully reassemble them.