Experts question study claiming to pinpoint birthplace of all humans

[jpak]

https://www.sciencemag.org/news/2019/10/experts-question-study-claiming-pinpoint-birthplace-all-humans

A new genetic study suggests all modern humans trace our ancestry to a single spot in southern Africa 200,000 years ago. But experts say the study, which analyzes the DNA of living people, is not nearly comprehensive enough to pinpoint where our species arose.

“I’m persuaded that southern Africa was an important area for human evolution,” says population geneticist Aylwyn Scally of the University of Cambridge in the United Kingdom who was not involved with the work. But, he says, studies of living people’s DNA can’t reveal the precise location of our ancestors. “It would be astonishing if all our genetic ancestry at this time arose in one small homeland.”

Modern humans arose in Africa at least 250,000 to 300,000 years ago, fossils and DNA reveal. But scientists have been unable to pinpoint a more specific homeland because the earliest Homo sapiens fossils are found across Africa, and ancient DNA from African fossils is scarce and not old enough.

In the new study, researchers gathered blood samples from 200 living people in groups whose DNA is poorly known, including foragers and hunter-gatherers in Namibia and South Africa who speak Khoisan languages with click consonants. The authors analyzed the mitochondrial DNA (mtDNA), a type of DNA inherited only from mothers, and compared it to mtDNA in databases from more than 1000 other Africans, mostly from southern Africa. Then the researchers sorted how all the samples were related to each other on a family tree.

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