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Author Topic:   New Type of Ancient Human Found—Descendants Live Today?
ramoss
Member (Idle past 612 days)
Posts: 3228
Joined: 08-11-2004


Message 1 of 209 (597615)
12-22-2010 6:25 PM


http://news.nationalgeographic.com/...volution-fossil-finger
A previously unknown kind of humanthe Denisovanslikely roamed Asia for thousands of years, probably interbreeding occasionally with humans like you and me, according to a new genetic study.
In fact, living Pacific islanders in Papua New Guinea may be distant descendants of these prehistoric pairings, according to new analysis of DNA from a girl's 40,000-year-old pinkie bone, found in Siberian Russia's Denisova cave.
This "new twist" in human evolution adds substantial new evidence that different types of humansso-called modern humans and Neanderthals, modern humans and Denisovans, and perhaps even Denisovans and Neanderthalsmated and bore offspring, experts say.
"We don't think the Denisovans went to Papua New Guinea," located at the northwestern edge of the Pacific region called Melanesia, explained study co-author Bence Viola, an anthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
"We think the Denisovan population inhabited most of eastern Eurasia in the same way that Neanderthals inhabited most of western Eurasia," Viola said. "Our idea is that the ancestors of Melanesians met the Denisovans in Southeast Asia and interbred, and the ancestors of Melanesians then moved on to Papua New Guinea."
(See "Interspecies Sex: Evolution's Hidden Secret?")
Interbreeding Common Among Various Types of Humans?
Taken together with a May DNA study that found Neanderthals also interbred with modern human ancestors, the Denisovan finding suggests there was much more interbreeding among different human types than previously thought, Stanford University geneticist Brenna Henn said.
"In the actual archaeological record, people have been talking about this for a long time ... But before six months ago, there was no genetic evidence for any admixture between archaic humans and modern humans," said Henn, who co-authored an article accompanying the study in tomorrow's issue of the journal Nature.
"Then these two papers come out, and I won't say they've turned the field on its head, but they certainly support a view that has not been well recognized for years" by geneticists, said Henn, who wasn't part of the study.
Brian Richmond, a paleoanthropologist at George Washington University, said he expects the new study to spark much interest and excitement.
"Nothing is more intriguing than learning new twists about our origins," said Richmond, who also didn't participate in the Denisovan-genetics research. "And this is another new twist."
Fossil Finger Points to New Human Type
The centerpiece of the DNA study is a Denisovan fossil finger bone discovered in 2008. The fossil is thought to be from a young girldubbed X-womanwho was 5 and 7 years old when she died.
For a previous Nature study, released in March 2010, the team had collected and sequenced mitochondrial DNA, or mtDNA, from X-woman's finger. But mtDNAinherited only from motherscontains far less information about a person's genetic makeup than DNA found in the nucleus of a cell, or nuclear DNA (quick genetics overview).
In the new study the team reports successfully extracting and sequencing so-called nuclear DNA from the bone.
Then, using DNA-comparison techniques, the scientists were able to determine that Denisovans were distinct from both modern humans and Neanderthals, yet closely related to the latter.
The team estimates Denisovans split from the parent group of Neanderthals about 350,000 years ago.

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 Message 2 by Coyote, posted 12-22-2010 6:37 PM ramoss has not replied

  
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