Convoluted human evolution: A missing branch? (Introduction)

by David Turell @, Saturday, September 24, 2016, 00:15 (809 days ago) @ David Turell

Study of Australian Aboriginal DNA indicates they are cross-bred with an unknown branch of humans:

"The genetic analyses revealed the genomes of present-day aboriginal Australians might harbor evidence of ancient interbreeding with an unknown human lineage.
"Who these people are, we don't know," said Eske Willerslev at the University of Copenhagen in Denmark, and senior author of one of the three studies.

"Previous research unearthed bones from a mysterious extinct branch of the human family tree from Denisova cave in Siberia's Altai Mountains. Analysis of DNA extracted from the fossils suggested these "Denisovans" shared a common origin with Neanderthals, but were nearly as genetically distinct from Neanderthals as Neanderthals were from living people. [Denisovan Gallery: Tracing the Genetics of Human Ancestors]

"Recent work suggested that Denisovans have contributed about 5 percent of their DNA to the genomes of present-day people of the Pacific islands of Oceania. However, these new findings suggest that what seemed to be evidence of Denisovans in the Pacific were actually signs of an unknown human lineage.

"'These guys were very distantly related to Denisovans, but by no means Denisovan," Willerslev told Live Science. "They were even more distantly related to Neanderthals, and they might have been even more distantly related to modern humans. We believe that they interbred with modern humans shortly before modern humans crossed into the ancient continent of Sahul — what is now Australia, New Guinea and Tasmania — some 50,000 to 60,000 years ago."


"The scientists also discovered that aboriginal Australians "are one of the oldest living populations on Earth, and have been in the same area for the past 50,000 to 60,000 years," Willerslev said.


"There was a great deal of controversy "over whether or not aboriginal Australians directly descend from the first humans entering Australia," Willerslev said. "The answer to that question is yes — our data is completely consistent with aboriginal Australians descending from the first humans to enter Australia. It shows a very long connection between those people and the land. [How Did Life Arise on Earth]
"I can't think of any other place in the world where humans have been so long in the same spot as Australia," Willerslev said. "Yes, there are populations in Africa that are older, but we have no idea if they stayed in the same area in Africa for as long a time."

"'We found that because aboriginal Australians have spent such a long time in Australia, they are very genetically diverse," Willerslev said. "An aboriginal Australian from eastern Australia and one from southwestern Australia are almost as different genetically as an Asian is from a European."
The researchers noted that about 90 percent of aboriginal Australians speak languages belonging to a single linguistic family, "but some people in northwest Australia speak other language families," Willerslev said. "It'd be very interesting to see what the story is there when it comes to how they migrated to Australia.'"

Comment: Not surprising, since evolution appears to be a bush not a tree, and human development can certainly follow the same pattern.

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