School has recovered and sequenced the DNA from a thighbone of a male
hunter-gatherer who lived in what is now Siberia 45,000 years ago.
...
The sequence revealed that the bone came from an anatomically modern human,
a man whose remains are the oldest ever found and carbon-dated outside of
Africa and the Middle East.
Comparison to diverse humans around the world today showed that the
Ust’-Ishim man was a member of one of the most ancient non-African
populations.
“The ancient Siberian was related equally to West European hunter-gatherers,
North Asian hunter-gatherers, East Asians, and the indigenous people of the
Andaman Islands off South Asia,” said Dr Fu, who is the first author of a
paper published in the journal Nature.
“The fact that this population separated so early indicates that theories
of an early split of people who followed a coastal route to Australia, New
Guinea, and coastal Asia are not strongly supported by this data.”
...
The scientists also obtained a high-resolution estimate of the mutation
rate in humans.
Previous studies had given scientists evidence of two possible rates, one
twice as fast as the other. Because of this large range, dates obtained
from genetic research have tended to be quite uncertain.
By measuring the number of mutations missing in the Ust’-Ishim man and
comparing with people now, the scientists obtained an accurate estimate
of the rate that mutations accumulated over time. They revealed a slower
mutation rate, corresponding to between one to two mutations per genome
per year.
...
“Instead of humans and Neanderthals becoming distinct offshoots sometime
between 270,000 and 380,000 years ago, for example, the slower rate would
put that shift much further back in time, between 550,000 and 770,000
years ago.”
“Similarly, the slower rate pushes back estimates for the date of the
separation of African and non-African populations.”
The slow mutation rates indicate that the present-day subdivisions among
human populations date back to almost 200,000 years ago, well before the
period around 50,000 years ago when the archaeological record documents
art and new styles of tool-making.
...
The researchers also found that about 2.3 percent of the Ust’-Ishim man’s
genome came from Neanderthals.
The genomic segments of Neanderthal ancestry are substantially longer than
those observed in present-day individuals, indicating that Neanderthal gene
flow into the ancestors of this individual occurred 7,000-13,000 years
before he lived (i.e. 58,000-52,000 years ago – a much tighter window than
the previous range of between 37,000 and 86,000 years ago).
... http://www.nature.com/nature/journal/v514/n7523/full/nature13810.html http://www.sci-news.com/genetics/science-genome-45000-year-old-siberian-man-02227.html
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