Dr. Medallon
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No pongo la traduccion hecha por alguna aplicacion porque son como la callampa, si le interesa leer aplique sus conocimientos
Scientists have extracted the entire genome of a 130,000-year-old Neanderthal from a single toe bone in a Siberian cave, an accomplishment that far outstrips any previous work on Neanderthal genes.
The accuracy of the new genome is of similar quality to what scientists would achieve if they were sequencing the DNA of a living person.
“It’s an amazing technical accomplishment,” said Sarah A. Tishkoff, an expert on human evolution at the University of Pennsylvania, who was not involved in the research. “Twenty years ago, I would have thought this would never be possible.”
The new Neanderthal genome, which is described in the current issue of Nature, is part of an extraordinary flurry of advances in studying ancient human DNA. Earlier this month, for example, scientists reconstructed a small segment of genes from a 400,000-year-old fossil in Spain, setting a record for the oldest human DNA ever found.
While the Spanish DNA only provided faint, tantalizing clues about human evolution, the new Neanderthal genome is more like a genetic encyclopedia, rich with new insights. The Neanderthal to whom the bone belonged was highly inbred, for example, offering a glimpse into the social lives of Neanderthals.
The new Neanderthal genome also contains evidence of more interbreeding between ancient human populations than previously known.
The authors of the new study also compared the Neanderthal genome to modern human DNA to better understand what makes our own lineage unique. They have come up with a list of mutations that evolved in modern humans after their ancestors branched off from Neanderthals some 600,000 years ago.
“The list of modern human things is quite short,” said John Hawks, a paleoanthropologist at the University of Wisconsin who was not involved in the study.
Neanderthals have intrigued scientists ever since their first fossils were found in 1856. Experts argued whether they were part of our own species or a separate one. Since the initial discovery, researchers have found remains of these heavy-browed, solidly built humans from Spain to Central Asia. Their fossil record now stretches from about 200,000 years ago to about 30,000 years ago.
Some of these fossils still hold fragments of Neanderthal DNA. In 1997, Svante Paabo of the Max Planck Institute for Evolutionary Anthropology and his colleagues extracted a snippet from a 40,000-year-old Neanderthal fossil. In 2010, after gathering more DNA from fossils, Dr. Paabo’s team published a rough draft of the entire Neanderthal genome.
Using improved methods, the scientists were able to reconstruct the genome from another trove of DNA from an 80,000-year-old finger bone retrieved by a team of Russian explorers from a cave called Denisova.
Much to their surprise, the genome belonged to a separate lineage of humans that had not been known from the fossil record before. The scientists called these mysterious people the Denisovans.
By comparing the rough drafts of the Denisovan and Neanderthal genomes to modern human DNA, Dr. Paabo and his colleagues found clues to how we’re all related. Modern humans, Neanderthals and Denisovans all descended from a common ancestor that lived several hundred thousand years ago. The ancestors of modern humans then branched away on their own lineage. It wasn’t until later that Neanderthals and Denisovans split apart from each other.
The researchers also discovered some Neanderthal and Denisovan DNA in the genomes of living humans.
Dr. Paabo and his colleagues concluded that modern humans interbred with both Neanderthals and Denisovans before those two lineages became extinct.
The scientists then developed better methods for reconstructing ancient DNA. They were able to create a new version of the Denisovan genome that was extremely accurate and complete.
There was just one catch: the latest reconstruction methods demanded a lot of ancient DNA, which is a rare thing to find in fossils. But when Dr. Paabo and his colleagues studied more bones from Denisova, they hit the jackpot again, discovering an abundance of DNA in a toe bone.
Bence Viola
A computer-generated image of a single Neanderthal toe bone found in a Siberian cave in 2010.
“We thought it would be a Denisovan toe,” said Dr. Paabo, “but it very clearly was a Neanderthal.”
The scientists were able to reconstruct the new Neanderthal genome even more accurately than the Denisovan one.
http://www.nytimes.com/2013/12/19/science/toe-fossil-provides-complete-neanderthal-genome.html?_r=1&
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