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  • Researchers say they traced the origins of all humans to a region located in the north of Botswana.

    Researchers say they traced the origins of all humans to a region located in the north of Botswana. | Photo: Reuters

Published 28 October 2019
Opinion

The study is based on investigating the human family tree through the analysis of more than a hundred samples of mitochondrial DNA.

Scientists claim they traced the origins of all humans currently alive to a region located near the Zambezi river in the north of Botswana, pinpointing the area as humankind's ancestral home, according to a study published Monday in the scientific Nature.

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The region which is today dominated by salt pans was some 200,000 years ago home to a lake with the size of New Zealand, known as Lake Makgadikgadi, that may have been the ancestral homeland of humanity, according to the researchers.

The researchers suggest our ancestors may have settled there about 70,000 years before local climate changes force them to move on. Shifts in rainfalls across the area led to three waves of migration 130,000 and 110,000 years ago, as people started to follow fertile green corridors, paving the way to early humans who began this way to spread into new territories.

The first wave of migrants went north-east, the second one ventured south-west and the third group of people remained in the homeland until today.

The study is based on investigating the human family tree through the analysis of more than a hundred samples of mitochondrial DNA (the scrap of DNA that passes down the maternal line from mother to child) from people living in southern Africa.

By combining genetics with geology and climate computer model simulations, the investigators could paint a picture of what the African continent might have been like 200,000 years ago.

"It has been clear for some time that anatomically modern humans appeared in Africa roughly 200,000 years ago," said Vanessa Hayes, a geneticist at the Garvan Institute of Medical Research in Australia.

"What has been long debated is the exact location of this emergence and subsequent dispersal of our earliest ancestors."

"It's an extremely large area, it would have been very wet, it would have been very lush," said Hayes. "And it would have actually provided a suitable habitat for modern humans and wildlife to have lived."

However, Hayes and her colleagues’ conclusions have drawn skepticism from other scientists who argue the story of humanity can not be constructed from mitochondrial DNA alone.

"I’m definitely cautious about using modern genetic distributions to infer exactly where ancestral populations were living 200,000 years ago, particularly in a continent as large and complex as Africa,” Chris Stringer of the Natural History Museum in London said, adding that evolution of Homo sapiens was a complex process.

“Like so many studies that concentrate on one small bit of the genome, or one region, or one stone tool industry, or one ‘critical’ fossil, it cannot capture the full complexity of our mosaic origins, once other data are considered.”

Thus, there could have been many homelands, rather than one, which has yet to be determined.

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