Scientists mapping genetic blueprint of Neanderthals

[Strengthandhonour]

Scientists mapping genetic blueprint of Neanderthals
By Dan Vergano, USA TODAY Thu Nov 16, 6:53 AM ET

Scientists probing a 38,000-year-old bone fragment may be within two years of deciphering the genetic blueprint of Neanderthals, humanity's prehistoric cousins, according to two studies out Wednesday.
Completing the genome - or genetic map - of Neanderthals would open a window on how humans evolved from the ancestors of chimps, our closest living genetic relatives, about 6 million years ago, says Svante Paabo of Germany's Max-Plank Institute for Evolutionary Anthropology, who collaborated on studies published in the journal nature and science. By comparing a Neanderthal genome to already completed genomes for humans and chimps, he suggests, researchers will gain insight into which genes have evolved most recently in modern humans, and which truly set us apart from other animals.

"Obviously it's just really cool to get genetic results for Neanderthals," says genetics researcher Bruce Lahn of the University of Chicago, who was not part of the study. "But this is an important proof of principle for a Neanderthal genome, which if completed would give us a tremendous look into the recent evolution of our species."

Large-boned and stocky, built for cold weather, Neanderthals disappeared from the fossil record in Europe about 30,000 years ago. Researchers hope that uncovering their ancient DNA may reveal their fate and shed light on the evolution of modern humans.

"Clearly, we are at the dawn of Neanderthal genomics," says Science study author Edward Rubin of Lawrence Berkeley (Calif.) National Laboratory. "No question we will have a Neanderthal genome."

"These papers are perhaps the most significant contributions published in this field since the discovery of Neanderthals 150 years ago," conclude molecular biologists David Lambert and Craig Millar of New Zealand's University of Auckland in a commentary accompanying the Nature study.

The findings presented Wednesday suggest that modern people and Neanderthals split genetically from a common ancestor at least 370,000 years ago. The papers present only a small slice, just 0.1%, of the complete genetic map of Neanderthals. Both studies are based on analysis of a few grams of a 38,000-year-old thighbone from a male Neanderthal found inside a Croatian cave.

Whether these "cavemen" were killed off by early modern humans, or disappeared through generations of mating, has been a subject of bitter scholarly debate for decades. The study results, finding Neanderthals have small genetic differences that make them at least 99.5% similar to humans, argue against large-scale blending after the genetic break between the species, but does not rule out some small-scale interbreeding later on.

Since 1997, researchers led by Paabo have identified traces of less fundamental maternal DNA from Neanderthals. The new research reveals the "nuclear" DNA found in the center of cells, sequenced in only a few months, reviving Neanderthal genetics, a field that appeared on the verge of going moribund a few years ago.

Lahn and colleagues recently released a Proceedings of the National Academies of Science study that suggests a potentially intelligence-related gene may have migrated from Neanderthals to humans about 37,000 years ago, from just a few matings. "A (Neanderthal) genome would put our claim to the test," Lahn says. "I have my fingers crossed they will find the sequence."

The bone sample studied in both papers contained contamination from bacteria and its human discoverers, Paabo says. Much of the teams' work involved statistical analysis designed to weed out this contamination, perhaps 95% of the genes uncovered, even using new gene sequencing technology. Paabo's team tested 70 Neanderthal fossils before finding one with some DNA remains.

Dwarfing past analyses of maternal DNA, the new techniques yielded 62,250 "base pairs" (the basic chemical unit of each gene) of Neanderthal DNA in the Science study and 1 million base pairs in the Nature study. For perspective, the human genome contains about 3 billion base pairs. Given the contamination concerns, researchers will likely have to sequence about 60 billion base pairs of genes to create the Neanderthal genome, says Michael Egholm of 454 Life Sciences, whose firm contributed the sequencing machines for "Project Flintstone," as they called the Nature study effort.

"The results are a real triumph, getting this number of sequences," says paleoanthropologist John Hawks of the University of Wisconsin, Madison. He cautioned that any Neanderthal genome will likely have "a lot of gaps," at first. Hawks adds that a flurry of studies on Neanderthal genetics have been published in recent months, alongside fossil findings. "It really is a flourishing area."

source: http://news.yahoo.com/s/usatoday/200...ofneanderthals