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- EVERYONE SEEMS NORMAL UNTIL YOU GET TO KNOW THEM! -

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Middle aged hetrosexual, WASP male. Middle of the road, reasonably sane and  reasonably employed.

Wednesday, July 18, 2007

My home town! (Tree)

A just completed analysis of thousands of skulls shows modern humans originated from a single point in Africa, and finally lays to rest the idea of multiple origins, British scientists said on Wednesday.

Most researchers agree that mankind spread out of Africa starting about 80,000 years ago and slowly established Stone Age cultures throughout Europe, Asia and Australia.

But a minority have argued, using skull data, that divergent populations evolved independently in different areas.

The genetic evidence has always strongly supported the single origin theory, and now results from a study of more than 6,000 skulls held around the world in academic collections supports this case.

"We have combined our genetic data with new measurements of a large sample of skulls to show definitively that modern humans originated from a single area in Sub-Saharan Africa," said Andrea Manica of the University of Cambridge's Department of Zoology.

Manica and colleagues wrote in the journal Nature that variations in skull size and shape decreased the further a skull was away from Africa, just like variations in DNA.

According to old family albums, this is the tree and savanna that my distant ancestors used to call home.


(Makes me feel sort of nostalgic to see it once again!)

The decrease reflects the fact that, while the original African population was stable and varied, only a small number of people embarked on each stage of the multi-step migration out of Africa. This effectively created a series of "bottlenecks," which reduced diversity.

The highest level of variation in skull types was seen in southeastern Africa, the generally accepted cradle of mankind.

The Cambridge work also suggests in-breeding with other early humans, such as Neanderthals, either did not happen or was insignificant. That is in contrast to recent suggestions that such hybrids may have been fairly common.

"We're not saying there was never a single mating between a homo sapiens and a Neanderthal. But I can say, very confidently, that whatever the product of that mating was, it didn't breed back into the population," Manica told Reuters.

Chris Stringer, a palaeoanthropologist at the Natural History Museum in London, said the new research was important for indicating that modern human diversity was derived entirely from Africa rather than coming from inter-mixing elsewhere.

Your "Leaky Smeaky" scribe;
Allan W Janssen

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