Re: Things that make you go hmmmmmmmmm
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Who were the Denisovans?
Unfortunately, the Denisovan genome doesn't provide many more clues about what this hominin looked like than a pinky bone does. The researchers will only conclude that Denisovans likely had dark skin. They also note that there are alleles "consistent" with those known to
call for brown hair and brown eyes. Other than that, they cannot say.
Yet the new genetic analysis does support the hypothesis that Neandertals and Denisovans were more closely related to one another than either was to modern humans. The analysis suggests that
the modern human line diverged from what would become the Denisovan line as long as 700,000 years ago—but possibly as recently as 170,000 years ago.
Denisovans also
interbred with ancient modern humans, according to Pääbo and his team. Even though the sole fossil specimen was found in the mountains of Siberia,
contemporary humans from Melanesia (a region in the South Pacific) seem to be the most likely to harbor Denisovan DNA. The researchers estimate that some 6 percent of contemporary Papuans' genomes come from Denisovans. Australian aborigines and those from Southeast Asian islands also have traces of Denisovan DNA. This suggests that the two groups might have crossed paths in central Asia and then the modern humans continued on to colonize the islands of Oceania.
Yet
contemporary residents of mainland Asia do not seem to posses Denisovian traces in their DNA, a "very curious" fact, Hawks says. "We're looking at a very interesting population scenario"—
one that does not jibe entirely with what we thought we knew about how waves modern human populations migrated into and through Asia and out to Oceania's islands. This new genetic evidence might indicate that perhaps an early wave of humans moved through Asia, mixed with Denisovans and then relocated to the islands—to be replaced in Asia by later waves of human migrants from Africa. "It's not totally obvious that that works really well with what we know about the diversity of Asians and Australians," Hawks says. But further genetic analysis and study should help to clarify these early migrations.
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The new research reveals that the
Denisovans had low genetic diversity—just 26 to 33 percent of the genetic diversity of contemporary European or Asian populations. And for the Denisovans, the population on the whole seems to have been very small for hundreds of thousands of years, with relatively little genetic diversity throughout their history.
Curiously, the researchers noted in their paper, the Denisovan population shows "
a drastic decline in size at the time when the modern human population began to expand."
Why were modern humans so successful whereas Denisovans (and Neandertals) went extinct? Pääbo and his co-authors could not resist looking into the genetic factors that might be at work. Some of
the key differences, they note, center around brain development and synaptic connectivity. "It makes sense that what pops up is connectivity in the brain," Pääbo noted. Neandertals had a similar brain size–to-body ratio as we do, so rather than cranial capacity, it might have been
underlying neurological differences that could explain why we flourished while they died out, he said.
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Read more here:
http://www.scientificamerican.com/article.cfm?id=denisovan-genomeThe above article is very interesting. We didn't even know about these people until 2010.
How many others do we not know about?
The archeological record is very slim and hit or miss at best. The information referenced above comes from one small bone in the finger and two teeth.
Imagine...
We don't know and, most likely, cannot even conceive of the diversity of humans that might have existed at one time in our distant past.
How did they survive? What were their communities like? We simply don't know.
What skills did they possess that we do not? Again, we simply don't know.
Imagine...