Prisoner Of Ice
03-28-2014, 05:52 AM
http://dienekes.blogspot.com/2014/03/oldest-modern-human-genome-from-siberia.html
In 2008, Siberian ivory carver Nikolay Peristov was searching for ancient mammoth tusks eroding from the banks of the Irtysh River in western Siberia, when he found fossilized bones instead. Back in his workshop in Omsk, he showed the bones to local paleontologist Aleksey Bondarev, who recognized a human thighbone. Bondarev in turn showed it to an anthropologist friend, and it was passed on up the chain to some of the world's top experts in human evolution. They dated it to 45,000 years ago, making it one of the oldest known modern humans in northern Asia and Europe.
Now, the bone has opened a window on the genetics of our species at a crucial moment: soon after their arrival in northern Eurasia. At a meeting* here last week, paleogeneticist Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, announced that his team has sequenced the thighbone's entire nuclear genome to high accuracy—an astonishing 42x coverage. "This is by far the oldest sequenced genome of a modern human," he said.
Because all living people in Europe and Asia carry roughly the same amount of Neandertal DNA, Pääbo's team thought that the interbreeding probably took place in the Middle East, as moderns first made their way out of Africa. Middle Eastern Neandertal sites are close to Skhul and Qafzeh, so some researchers suspected that those populations were the ones that mingled. But the team's analysis favors a more recent rendezvous. The femur belonged to an H. sapiens man who had slightly more Neandertal DNA, distributed in different parts of his genome, than do living Europeans and Asians. His Neandertal DNA is also concentrated into longer chunks than in living people, Pääbo reported. That indicates that the sequences were recently introduced: With each passing generation, any new segment of DNA gets broken up into shorter chunks as chromosomes from each parent cross over and exchange DNA. Both features of the Neandertal DNA in the femur suggest that the Ust-Ishim man lived soon after the interbreeding, which Pääbo estimated at 50,000 to 60,000 years ago.
45k year old genome shows higher neanderthal percentage than people do today, and in different areas.
It should be kept in mind neanderthals would not all be exactly the same, they would vary like people do today.
Interestingly finding a higher percentage in ancient fossil is not new. Otzi the iceman had twice as much as most people today. 25k years ago there is a full fledged 50/50 hybrid sequenced as well. So it shows a steady loss in neanderthal DNA over time. Today it's 3%, 6k years ago it was 6% and 25k years ago it was 50% and the youngest full neanderthals were around 30k years- so we have lost about half our neanderthal dna every 6k years.
This guy was further east so probably on outside range of neanderthal territory - at the same time neanderthals were still going strong in Iberia. So I don't expect this exact pattern to hold for him, but his mixture pattern makes it obvious it was not a one time thing as it was once presumed.
In 2008, Siberian ivory carver Nikolay Peristov was searching for ancient mammoth tusks eroding from the banks of the Irtysh River in western Siberia, when he found fossilized bones instead. Back in his workshop in Omsk, he showed the bones to local paleontologist Aleksey Bondarev, who recognized a human thighbone. Bondarev in turn showed it to an anthropologist friend, and it was passed on up the chain to some of the world's top experts in human evolution. They dated it to 45,000 years ago, making it one of the oldest known modern humans in northern Asia and Europe.
Now, the bone has opened a window on the genetics of our species at a crucial moment: soon after their arrival in northern Eurasia. At a meeting* here last week, paleogeneticist Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, announced that his team has sequenced the thighbone's entire nuclear genome to high accuracy—an astonishing 42x coverage. "This is by far the oldest sequenced genome of a modern human," he said.
Because all living people in Europe and Asia carry roughly the same amount of Neandertal DNA, Pääbo's team thought that the interbreeding probably took place in the Middle East, as moderns first made their way out of Africa. Middle Eastern Neandertal sites are close to Skhul and Qafzeh, so some researchers suspected that those populations were the ones that mingled. But the team's analysis favors a more recent rendezvous. The femur belonged to an H. sapiens man who had slightly more Neandertal DNA, distributed in different parts of his genome, than do living Europeans and Asians. His Neandertal DNA is also concentrated into longer chunks than in living people, Pääbo reported. That indicates that the sequences were recently introduced: With each passing generation, any new segment of DNA gets broken up into shorter chunks as chromosomes from each parent cross over and exchange DNA. Both features of the Neandertal DNA in the femur suggest that the Ust-Ishim man lived soon after the interbreeding, which Pääbo estimated at 50,000 to 60,000 years ago.
45k year old genome shows higher neanderthal percentage than people do today, and in different areas.
It should be kept in mind neanderthals would not all be exactly the same, they would vary like people do today.
Interestingly finding a higher percentage in ancient fossil is not new. Otzi the iceman had twice as much as most people today. 25k years ago there is a full fledged 50/50 hybrid sequenced as well. So it shows a steady loss in neanderthal DNA over time. Today it's 3%, 6k years ago it was 6% and 25k years ago it was 50% and the youngest full neanderthals were around 30k years- so we have lost about half our neanderthal dna every 6k years.
This guy was further east so probably on outside range of neanderthal territory - at the same time neanderthals were still going strong in Iberia. So I don't expect this exact pattern to hold for him, but his mixture pattern makes it obvious it was not a one time thing as it was once presumed.