By Will Dunham
WASHINGTON (Reuters) – A large swampy region of northern Botswana – once full of life but now dominated by desert and salt flats – may represent the ancestral homeland of all 7.7 billion people on Earth today, researchers said Monday. market .
Their study, guided by maternal DNA data from more than 1,200 indigenous people from southern Africa, proposed a central role for this region in early human history from 200,000 years ago, feeding our species for 70,000 years before the changes. climate paved the way for the first migrations.
A lake that was once the largest in Africa – twice the area of present-day Lake Victoria – gave rise to the ancient wetlands that cover the Great Zambezi basin, which includes northern Botswana in Namibia to the west and Zimbabwe, to the east, the researchers said.
It has long been established that Homo sapiens originated somewhere in Africa before spreading around the world.
"But what we didn't know until this study was exactly where this homeland was," said geneticist Vanessa Hayes of the Garvan Institute for Medical Research and University of Sydney, who led the study in the journal Nature.
The earliest known fossil evidence of Homo sapiens dates back over 300,000 years from Morocco. The new study suggests that the first members of our species, represented by the remains of Morocco, may not have left any ancestors alive today, the researchers said.
"There is no contradiction between the presence of an early Homo sapiens skull in North Africa, which may be from an extinct lineage, and the proposed South African origin of the still living Homo sapiens lineages," added the co-author. of the study. Axel Timmermann, climate physicist at Pusan National University in South Korea.
The ancient Makgadikgadi Lake began to break about 200,000 years ago, giving rise to a flooded region inhabited by human hunter-gatherers, the researchers said.
"It can be seen as a large expanse of wetland in the Okavango Delta today," said Timmermann.
Changes in the Earth's axis and orbit caused changes in climate, rainfall, and vegetation that set the stage for the early migrations of this ancestral group of people away from their homeland, first to the northeast 130,000 years ago, then to the southwest. 110,000 years ago, added Timmermann.
"Our study provides the first well-dated quantitative evidence that astronomical climate change in the past has caused major human migration events, which has led to the development of genetic diversity and eventually to cultural, ethnic and linguistic identity," added Timmermann. (Report by Will Dunham)
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