Genetic research is rediscovering African human populations thought to have disappeared

South Africa probably has the greatest human genetic diversity on Earth, and new research shows that diversity is in better shape than previously thought. When some of the languages ​​of the Namibian desert died out, anthropologists feared that the populations that spoke them would disappear too, but new research shows that people have retained their genetic identity even without a native language.

A common pattern is that biodiversity is greatest in the place where the species or genus originated. Although some non-scientists disagree, anthropologists would know that humans evolved in Africa even without fossil records, just by looking at how much more diverse we are. This can be seen most dramatically among the people of the Kalahari and Namibian deserts of southeastern Africa.

The Namibian is a long, thin desert that surrounds the coast of Namibia and parts of Angola and South Africa. Wars disrupted the North for decades and interfered with attempts to explore this diversity. The stabilization allowed representatives of the Portugal-Angola TwinLab to fill in some of the gaps, identifying patterns of ancient human prehistory in the process.

We were able to find groups that were thought to have disappeared more than 50 years ago, said Dr Jorge Rocha from the University of Porto. One of them is the Kwepe, who used to speak the Kwadi language, the disappearance of which marked the end of their separation from the neighboring population.

Kwadi was a click language that shared a common ancestor with the Khoe languages ​​spoken by foragers and pastoralists throughout southern Africa, said Dr. Ann-Maria Fehn of the Centro de Investigao em Biodiversidade e Recursos Genticos. As part of the project, the team found two survivors who remember much of the language living near the mouth of the Kuroka River, whom Fehn was able to interview.

The last two speakers of Kwadi, a language thought to be extinct in a population that retains its genetic distinctiveness

Image credit: Jorge Rocha

Using a combination of genetic and linguistic analysis, the researchers studied the relationships among the people of Namibia in Angola. They found the greatest genetic differences between populations with different lifestyles, farmers and herders, and more traditional hunter-gatherers, for example.

Kwadi may be nearly extinct, but the team found that the descendants of its speakers retain their genetic distinctiveness from before Bantu-speaking farmers moved into the area.

“Much of our effort has been to understand how much of this local variation and global eccentricity was caused by genetic drift, a random process that disproportionately affects small populations, and admixture from extinct populations,” said Dr. Sandra Oliverira of the University of Bern.

“Previous studies have shown that foragers from the Kalahari Desert are descended from an ancestral population that first diverged from all other extant humans,” added Professor Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology, who pioneered genome-wide studies of the South African desert. populations.

Our results consistently place the newly identified ancestry within the same ancestral lineage, but suggest that the Namibian-associated ancestry diverged from all other southern African ancestry, followed by a split between northern and southern Kalahari ancestry.

Angolan Namibia and the northern areas of Namibia are the only areas where this genetic heritage has been preserved at all.

The study allowed the team to reconstruct the migration of populations in the regions. Khoe-Kwadi speakers spread into the region about 2,000 years ago, possibly from what is now Tanzania. This makes them relatively latecomers compared to the first inhabitants who spoke Khoe languages and may have been in the area for hundreds of thousands of years. Bantu speakers arrived 200-500 years late from West and Central Africa.

Khoe speakers live in the region and share ancestry with the more studied Kalahari populations, while Bantu speakers are much less distinct from the rest of humanity. Populations that once spoke Kwadi before the introduction of Bantu languages ​​in recent decades are the missing piece of the human puzzle identified in this study.

The study is open access in Science Advances.