A new study that pinpoints Botswana as the origin of modern humans some 200,000 years ago has caused a flurry of debate among scientists, with some dismissing the research as deeply flawed.
The study pinpoints the Makgadikgadi-Okavango area of what is today northern Botswana as the origin of modern humans. The international team of scientists published their findings in the British scientific journal Nature.
The scientists studied the maternal DNA data of more than 1,200 indigenous people in southern Africa. According to their findings, Makgadikgadi-Okavango was the birthplace of humans 200,000 years ago, nurturing our species for 70,000 years before climate change paved the way for the first migrations. The area was once a massive lake, roughly twice the area of Lake Victoria.
The new findings also suggest that Botswana could be the most precise location of the "ancestral homeland" of humans ever pinpointed. While it has long been known that anatomically modern humans, or homo sapiens, originated in Africa, scientists had previously been unable to pin down an exact birthplace.
"We've known for a long time that modern humans originated in Africa roughly 200,000 years ago," said Vanessa Hayes, from the Garvan Institute of Medical Research and University of Sydney. "But what we hadn't known until the study was where exactly this homeland was."
New findings disputed
Until the new study was published, the scientific community had agreed that the earliest humans had originated in Eastern Africa, but that the exact location was yet to be determined.
Leading paleoanthropologist Professor Lee Rogers Berger, from the University of Witwatersrand in South Africa, told DW that the new study is deeply flawed.
"I think that there is a fundamental problem with this research. The extrapolation that these authors and scientists took to pinpoint a location in northern Botswana is quite frankly impossible. What they're trying to do is take a single line of evidence in a gene existing in people 200,000 years from the source of that gene in time," Berger said.
"Their argument is that those people have not moved from that area -- that there's been no integration from other areas. So they're using that to take a very extreme view."
"Archeological records tell us that the origins of modern humans in Africa are a very complex thing and I think that this study greatly oversimplified it, and perhaps it's perhaps gone way too far with the extrapolation that modern humans originated in in northern Botswana," Berger told DW.
The team of researchers said in a statement that it had used blood samples from people in Namibia and South Africa and combined the DNA with cultural and geographical data to show that "the first homo sapiens' maternal lineage emerged in a homeland south of the Greater Zambezi River Basin region." The region includes northern Botswana and parts of Namibia and Zimbabwe.
Professor Rebecca Ackermann of the Human Evolution Research Institute (HERI) in South Africa suggests that the evolution of our species is a complex topic and that the study covered only a small part of it.
"I was shocked by this study and think it was quite irresponsible," Ackerman said. "The research is too unsophisticated and narrow and there is not one anthropologist or archaeologist on the team." Diversity makes for better science, she added.
Other scientists have concurred, with Professor Chris Stringer from the Natural History Museum in London tweeting: "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."