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US News 'Ghost' ancestors: African DNA study detects mysterious human species

17:10  14 february  2020
17:10  14 february  2020 Source:   reuters.com

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The study indicated that present-day West Africans trace a substantial proportion, some 2% to 19%, of their genetic ancestry to an extinct They found DNA segments in the West Africans that could best be explained by ancestral interbreeding with an unknown member of the human family tree that led

Scientists examining the genomes of West Africans have detected signs that a mysterious extinct human species interbred with our own species tens of thousands of years ago in Africa , the latest evidence of humankind's complicated genetic ancestry .

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WASHINGTON (Reuters) - Scientists examining the genomes of West Africans have detected signs that a mysterious extinct human species interbred with our own species tens of thousands of years ago in Africa, the latest evidence of humankind's complicated genetic ancestry.

The study indicated that present-day West Africans trace a substantial proportion, some 2% to 19%, of their genetic ancestry to an extinct human species - what the researchers called a "ghost population."

JUNE 15: Rhodesian man skull (Homo rhodesiensis), profile. © Photo by DeAgostini/Getty Images JUNE 15: Rhodesian man skull (Homo rhodesiensis), profile. "We estimate interbreeding occurred approximately 43,000 years ago, with large intervals of uncertainty," said University of California, Los Angeles (UCLA) human genetics and computer science professor Sriram Sankararaman, who led the study published this week in the journal Science Advances.

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Scientists examining the genomes of West Africans have detected signs that a mysterious extinct human species interbred with our own species tens of thousands of years ago in Africa , the latest evidence of humankind's complicated genetic ancestry .

The study indicated that present-day West Africans trace a substantial proportion, some 2% to 19%, of their genetic ancestry to an extinct They found DNA segments in the West Africans that could best be explained by ancestral interbreeding with an unknown member of the human family tree that led

Homo sapiens first appeared a bit more than 300,000 years ago in Africa and later spread worldwide, encountering other human species in Eurasia that have since gone extinct including the Neanderthals and the lesser-known Denisovans.

Previous genetic research showed that our species interbred with both the Neanderthals and Denisovans, with modern human populations outside of Africa still carrying DNA from both. But while there is an ample fossil record of the Neanderthals and a few fossils of Denisovans, the newly identified "ghost population" is more enigmatic.

An employee of the Natural History Museum in London looks at model of a Neanderthal male in his twenties, which on display at the museums 'Britain: One Million Years of the Human Story' exhibition which opens on 13th February till 28th September 2014.   (Photo by Will Oliver/PA Images via Getty Images) © PA Images An employee of the Natural History Museum in London looks at model of a Neanderthal male in his twenties, which on display at the museums 'Britain: One Million Years of the Human Story' exhibition which opens on 13th February till 28th September 2014. (Photo by Will Oliver/PA Images via Getty Images)

Asked what details are known about this population, Sankararaman said, "Not much at this stage."

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Scientists examining the genomes of West Africans have detected signs that a mysterious extinct human species interbred with our own They found DNA segments in the West Africans that could best be explained by ancestral interbreeding with an unknown member of the human family tree that

Scientists think studying DNA from fossils of a Homo erectus descendant might offer clues to which They estimated that the ancestors of West Africans and the ghost archaic population interbred The scientists could not say what species of human the ghost archaic population belonged to.

"We don't know where this population might have lived, whether it corresponds to known fossils, and what its ultimate fate was," Sankararaman added.

Sankararaman said this extinct species seems to have diverged roughly 650,000 years ago from the evolutionary line that led to Homo sapiens, before the evolutionary split between the lineages that led to our species and to the Neanderthals.

The researchers examined genomic data from hundreds of West Africans including the Yoruba people of Nigeria and Benin and the Mende people of Sierra Leone, and then compared that with Neanderthal and Denisovan genomes. They found DNA segments in the West Africans that could best be explained by ancestral interbreeding with an unknown member of the human family tree that led to what is called genetic "introgression."

It is unclear if West Africans derived any genetic benefits from this long-ago gene flow.

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The study indicated that present-day West Africans trace a substantial proportion, some 2% to 19%, of their genetic ancestry to an extinct They found DNA segments in the West Africans that could best be explained by ancestral interbreeding with an unknown member of the human family tree that led

Science and Environment. African DNA study detects mysterious human species . Scientists examining the genomes of West Africans have detected signs that a mysterious extinct human species interbred with our own species tens of thousands of years ago in Africa , the latest evidence

Gallery: Recent discoveries that shattered anthropologists' picture of where humans came from (Insider)

          As      anthropologists have discovered            new species of human ancestors, our       understanding of human history has changed.               By sequencing the genomes from our       Neanderthal and Denisovan cousins, scientists have also      gained new insight into the genetic       origins of our species.         As researchers make more of these breakthroughs, the puzzle    of who we are and where we came from gets more complicated.        The earliest humans may have emerged much earlier, and in a    different place in the world, than scientists previously thought.                      Visit      Business Insider's homepage for more stories.           In recent years, anthropologists around the world have discovered        new human ancestors, figured out what happened to the    Neanderthals, and pushed back the age of the earliest member of    our species.      Taken together, these breakthroughs suggest that many of our    previous ideas about the human origin story - who we are and    where we came from - were wrong.      Until the last few years, most scientists thought that the first    members of our species, Homo sapiens, evolved in East Africa        approximately 200,000 years ago. Then humanity remained in    Africa for the next 140,000 years, according to this line of    thought, before venturing into Europe and Asia in what's known as    the

"We are beginning to learn more about the impact of DNA from archaic hominins on human biology," Sankararaman said, using a term referring to extinct human species. "We now know that both Neanderthal and Denisovan DNA was deleterious in general but there were some genes where this DNA had an adaptive impact. For example, altitude adaptation in Tibetans was likely facilitated by a Denisovan introgressed gene."

(Reporting by Will Dunham; Editing by Sandra Maler)

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