Origin of modern humans 'traced to Botswana'
By Helen Briggs -BBC - 28. October 2019
Scientists have pinpointed the homeland of all humans alive today to a region south of the Zambesi River.
The area is now dominated by salt pans, but was once home to an enormous lake, which may have been our ancestral heartland 200,000 years ago.
Our ancestors settled for 70,000 years, until the local climate changed, researchers have proposed.
They began to move on as fertile green corridors opened up, paving the way for future migrations out of Africa.
"It has been clear for some time that anatomically modern humans appeared in Africa roughly 200,000 years ago," said Prof 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."
Prof Hayes' conclusions have drawn scepticism from other researchers in the field, however.
The area in question is south of the Zambesi basin, in northern Botswana.
The researchers think our ancestors settled near Africa's huge lake system, known as Lake Makgadikgadi, which is now an area of sprawling salt flats.
"It's an extremely large area, it would have been very wet, it would have been very lush," said Prof Hayes. "And it would have actually provided a suitable habitat for modern humans and wildlife to have lived."
After staying there for 70,000 years, people began to move on. Shifts in rainfall across the region led to three waves of migration 130,000 and 110,000 years ago, driven by corridors of green fertile land opening up.
The first migrants ventured north-east, followed by a second wave of migrants who travelled south-west and a third population remained in the homeland until today.
This scenario is based on tracing back the human family tree using hundreds of samples of mitochondrial DNA (the scrap of DNA that passes down the maternal line from mother to child) from living Africans.
By combining genetics with geology and climate computer model simulations, researchers were able to paint a picture of what the African continent might have been like 200,000 years ago.
Reconstructing the human story
However, the study, published in the journal Nature, was greeted with caution by one expert, who says you can't reconstruct the story of human origins from mitochondrial DNA alone.
[N.B.: And of course there are Brits, who still want to try and confuse:]
Other analyses have produced different answers with fossil discoveries hinting at an eastern African origin.
Prof Chris Stringer of the Natural History Museum, London, who is not connected with the study, said the evolution of Homo sapiens was a complex process.
"You can't use modern mitochondrial distributions on their own to reconstruct a single location for modern human origins," he told BBC News.
"I think it's over-reaching the data because you're only looking at one tiny part of the genome so it cannot give you the whole story of our origins."
Thus, there could have been many homelands, rather than one, which have yet to be pinned down.
Evolutionary milestones in human history
- 400,000 years ago: Neanderthals - our evolutionary cousins - begin to appear and move across Europe and Asia
- 300,000 to 200,000 years ago:Homo sapiens - modern humans - appear in Africa
- 50,000 to 40,000 years ago: Modern humans reach Europe.
The ongoing genocide targeting the San / Bushman people of Southern Africa is the greatest shame of modern humanity.
and join the phalanx to defend the San / Bushman people in their struggle against the ongoing genocide:
Write to fPcN-InterCultural via secure email: to give a hand to the San Foundation of the genuine San / Bushman themseves.
Human origins in a southern African palaeo-wetland and first migrations
- Benedetta F. Baldi,
- Andy E. Moore,
- Ruth J. Lyons,
- Sun-Seon Lee,
- Anton M. F. Kalsbeek,
- Desiree C. Petersen,
- Hannes Rautenbach,
- Hagen E. A. Förtsch,
- M. S. Riana Bornman &
- Vanessa M. Hayes
Here we generate, to our knowledge, the largest resource for the poorly represented and deepest-rooting maternal L0 mitochondrial DNA branch (198 new mitogenomes for a total of 1,217 mitogenomes) from contemporary southern Africans and show the geographical isolation of L0d1’2, L0k and L0g KhoeSan descendants south of the Zambezi river in Africa.
By establishing mitogenomic timelines, frequencies and dispersals, we show that the L0 lineage emerged within the residual Makgadikgadi–Okavango palaeo-wetland of southern Africa7, approximately 200 ka (95% confidence interval, 240–165 ka). Genetic divergence points to a sustained 70,000-year-long existence of the L0 lineage before an out-of-homeland northeast–southwest dispersal between 130 and 110 ka. Palaeo-climate proxy and model data suggest that increased humidity opened green corridors, first to the northeast then to the southwest.
Subsequent drying of the homeland corresponds to a sustained effective population size (L0k), whereas wet–dry cycles and probable adaptation to marine foraging allowed the southwestern migrants to achieve population growth (L0d1’2), as supported by extensive south-coastal archaeological evidence8,9,10.
Taken together, we propose a southern African origin of anatomically modern humans with sustained homeland occupation before the first migrations of people that appear to have been driven by regional climate changes.
Ancestral homeland of modern humans in Botswana, study finds
Region south of the Zambesi river was once home to a enormous lake, roughly twice the area of modern-day Lake Victoria.
Scientists claim they have traced the homeland for all modern humans to a region of northern Botswana, south of the Zambezi River.
The area is now salt pans, but 200,000 years ago it was home to Homo Sapiens and hosted a population of modern humans for at least 70,000 years, according to a study released in the scientific journal Nature on Monday.
The group remained in the region until regional climate changes led them to migrate, roughly 130,000 years ago, first to the northeast then to the southwest.
"We've known for a long time that modern humans originated in Africa roughly 200,000 years ago," Vanessa Hayes, from the Garvan Institute of Medical Research and the University of Sydney said.
"But what we hadn't known until the study was where exactly this homeland was."
The area identified in the study was called Makgadikgadi-Okavango, once home to an enormous lake, roughly twice the area of modern-day Lake Victoria.
Scientists reached their conclusions after analysing DNA samples from 200 Khoisan people, an ethnic group living in modern-day South Africa and Namibia known to carry a high proportion of a branch of DNA known as L0.
Researchers then combined the DNA samples with geographical distribution, archaeological and climate change data to come up with a genomic timeline that suggested a sustained lineage of L0 stretching back 200,000 years.
Their work created a kind of genetic map tracing L0 lineage to show that prehistoric humans lived in the region for about 70,000 years before they dispersed throughout the world.
"Every time a new migration occurs, that migration event is recorded in our DNA as a time-stamp," Hayes told AFP news agency.
"Over time our DNA naturally changes, it's the clock of our history."
Scientists say their work shows the origin of modern humans to Botswana, south of the Zambezi River. [Al Jazeera]
Although there have been humanoid fossil remains believed to pre-date the 200,000-year benchmark named in the study, the team said their study of L0 data allows us to trace our lineage directly back to the region south of the Zambezi river.
"We're talking about anatomically modern humans, people living today," said Hayes.
"Everyone walking around today... it does actually come back to L0 being the oldest, and it all comes back to this one (region)."
The team said they wanted to collect more DNA samples to help refine their methods and better reconstruct the history of the first movements of our earliest ancestors.
Doubts about study
However, some researchers were not convinced by the study's findings.
Chris Stringer, who researches human evolution at the Natural History Museum in the UK, says the study of human origins is complex.
"I am very 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," he said in a statement posted on Twitter.
"Moreover, 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," he said.
He noted that other studies have suggested that our origins may be linked to West Africa and East Africa, not Southern Africa.
But the fact remains that the San / Bushmen are still alive and proof our all origin. Maybe that is the reason why white supremacists and those who robbed their lands want to get rid of them - nowadays faster than ever before, by even sending Non-San rapists into the last San communities to impregnate the girls or to lure the San girls into the cities.