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Homo sapiens: the scientists who claim to have identified the exact place from which modern humans come

The ancestral land of all living human beings is currently in southern Africa, more precisely south of the Zambeze River, according to a new study published in the journal Nature.

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The identified region is mainly in Botswana, with small parts in Namibia and Zimbabwe.
It was clear for a while that anatomically modern humans appeared in Africa about 200,000 years ago,” said Vanessa Hayes, a researcher at the Garvan Institute for Medical Research in Sydney, Australia, and lead author of the study.

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What has been discussed at length is the exact location of this appearance and the subsequent dispersion of our early ancestors.” Some scientists, however, question the conclusions of the study. The unexpected discovery of a “Homo sapiens” bone that suggests that humans have left Africa thousands of years earlier than previously believed.
The region identified by Hayes and his colleagues as the cradle of modern humans is currently deserted and with salt. But in the past it was a lake twice as big as Victoria. That great lake was divided into small parts about 200,000 years ago to form a vast wetland in which humans settled, according to the study.

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The region identified by the researchers is currently dry, but in the past it housed a large lake.
In that green region, modern humans remained around 70,000 years before dispersing and migrating, first to the northwest, then to the southwest and finally out of the African continent.

Before the emergence of the modern human being, the lake began to dry up due to a change in tectonic plates,” said Andy Moore, a geologist at the University of Rhodes in South Africa and another author of the study.

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Axel Timmermann, of the National University of Pusan, who also participated in the study, analyzed the geological data of South Africa over the last 250,000 years. According to the scientist, a change in weather conditions could create green corridors where our ancestors emigrated for the first time.

Scientists have reconstructed the lineage of modern humans using hundreds of blood samples from current settlers south of the Zambeze River to analyze their mitochondrial DNA, which passes to the new generation along the maternal line. Mitochondrial DNA is the genetic material of mitochondria, the elements of the cell that generate energy for it. It is the DNA that is found in these structures outside the nucleus.

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The mitochondrial DNA is not transmitted along the chromosomes present in most cellular genes, but is transmitted by the maternal egg during fertilization, therefore it is inherited exclusively by the parent.
That genetic material is, according to Hayes, a “time capsule” because it accumulates changes over the generations.

Our work would not have been possible without the generous contribution of local communities,” said Riana Bornam, professor of public health at the University of Pretoria in South Africa. The researchers combined genetic data with geological analyzes and climate simulation models to determine how the African region was identified in the study 200,000 years ago.

Combining lineage with linguistic, cultural and geographical distribution, the study revealed, according to its authors, the origin of the first “homo sapiens sapiens” (modern man). The conclusions of the study are questioned by other researchers.

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Humans with modern anatomical features, Homo sapiens sapiens, emerged between 300,000 and 200,000 years ago. Chris Stringer, an anthropologist at the Natural History Museum in London, not involved in the new study, told the BBC that the evolution of Homo sapiens is a complex process.
“It is not possible to use only modern mitochondrial DNA distributions to find a unique site where modern humans originated.

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I think that doing so would be to deduce more from the data than what they offer, because we are only looking at a very Pequén part of the genome, which cannot give complete information about our origins.For Stringer there could have been several ancestral lands, rather than one. Other studies also indicate that the origin of modern humans could be found in East Africa.

source:bbc.com 

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