LONDON: Scientists are to decipher the genetic code of our closest relative, the barrel-chested, long-faced Neanderthal, in the hope that it will reveal how modern humans developed the formidable cognitive power to dominate the world.
With fragments of DNA from bones found in ancient caves, researchers will piece together the Neanderthal's genome and compare it with those already sequenced for humans and chimps.]
Modern humans and Neanderthals split from a common ancestor nearly 500,000 years ago. From a foothold north of the Mediterranean, Homo heidelbergensis steadily evolved into the Neanderthals, while in Africa, the same species embarked on a different evolutionary path, ultimately resulting in Homo sapiens.
Remains of Neanderthals dating back as far as 400,000 years suggest a reasonably sophisticated species that crafted tools and weapons and buried its dead, but was no match for Homo sapiens. The last of them died out nearly 40,000 years ago, as Homo sapiens migrated to, and eventually settled throughout, Europe.
The team of scientists, led by Svante Paabo at the Max Planck Institute in Leipzig, will analyse strands of DNA preserved in a leg bone recovered from a cave in Vindija, Croatia, and an upper arm bone from an archaeological site in the Neander valley in Germany.
Contamination with microbes means only 5 per cent of the DNA collected from the bones belongs to Neanderthals, giving the scientists a huge sorting problem.
The effort to reconstruct the 3 billion building blocks of the genome is expected to take two years, using a rapid sequencing technique developed by a US company, 454 Life Sciences. The complete genome will be made publicly available for other researchers to study. Dr Paabo said: "If we're really interested in what makes us truly modern humans, we need to look at the genetic changes that have happened in the past 200,000 to 300,000 years, and to identify those changes we need to look at our closest relative, the Neanderthal."
While humans and chimps share 99 per cent of their genetic code, the remaining 1 per cent still amounts to about 35 million genetic tweaks that separate the species. The difference between modern humans and Neanderthals is much smaller, making it easier to pinpoint the genes that furnished us with distinguishing characteristics such as larger, complex brains and the ability to develop sophisticated language.
Recovery of the Neanderthal genome would be invaluable for reconstructing many events in human prehistory and evolution. It would help address such questions as whether Neanderthals and humans interbred, whether the archaic humans had an articulate form of language, how their brain was constructed, if they had light or dark skins, and how big the Neanderthal population was.
"The Neanderthal genome will tell us much more about human biology than sequencing any other individual around," said Michael Egholm, a molecular biologist at 454 Life Sciences. "The ultimate goal is to understand humans, with the real pot of gold for humanity being the genes associated with cognition. We want to know, what are the handful of genetic changes that separated modern humans from the Neanderthal?"
The Guardian, The New York Times
