Friday, August 31, 2012

Siberia to Australia and places in between

" All that was found of her was a tiny piece of her fossilised pinkie finger.
But the DNA of the archaic human girl who lived in Denisova Cave in Siberia more than 30,000 years ago has revealed she probably had dark skin, with brown eyes and brown hair."

Amazing what DNA can tell us.

" In a technical tour de force, researchers have worked out the complete genetic sequence of the girl from a tiny sample of DNA extracted from her bone.
The study suggests the mysterious group of ancient humans to which she belonged, dubbed the Denisovans, were probably few in number but populated a large area of Asia.
It also confirms some of her relatives interbred with the ancestors of Australian Aborigines, and Melanesian people living in Papua New Guinea and other islands today."

There is a problem here in that Australia was probably colonised by Aborigines 60 000 years ago so either the relatives were her ancestors or there has been a lot of people arriving in Australia for a very long time.
" Matthias Meyer, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, said the team's new technique even allowed them to distinguish between the DNA the girl inherited from her father and from her mother.
"This is an extinct genome sequence of unprecedented accuracy," Dr Meyer said."

Not sure how that works if relatives turned up in Australia unless of course they were ancestors and if that was the case why is the geome extinct ?
" The existence of the Denisovans only came to light in 2008, when the finger bone was discovered along with two teeth. They are the first group of extinct humans to be identified solely on the basis of their DNA.
A draft genome was published in 2010 and the new study compares the complete genome with that of the Denisovans' closest relatives, Neanderthals, as well as with 11 modern humans.
The results are published today in the journal Science."

This is all rather confusing  30,000 years ago modern humans were here  and had been for quite a while.
" It shows the girl had genetic variants which are associated in present-day people with brown skin, hair and eyes; and she may have lived as long as 82,000 years ago."

That make more sense from a time line perspective but I would have thought that carbon dating might have come up with a hard number to within a few thousand years at 82,000 that still gives a 22,000 year frame to get to Australia.  

" The team identified more than 100,000 small changes in the human genome which occurred after the split from a common ancestor with the Denisovans.
Svante Paabo, who led the team, said the changes affected genes associated with brain function and nervous-system development, and possibly the skin, eye and teeth."

In other words evolution.
"This research will help determine how it was that modern-human populations came to expand dramatically in size as well as cultural complexity, while archaic humans eventually dwindled in numbers and became extinct," Dr Paabo said.
The study also found that people in Eurasia and native Americans have more Neanderthal DNA than those in Europe, which suggests the theory that modern humans left Africa and interbred with Neanderthals in the Middle East, before spreading around the globe, is too simplistic.

Now if I lived in Siberia I am betting Australia would be a fairly attractive option.