2023-09-25 13:28:02
Kuvale settlement in Virei, Namibe province in Angola. – SANDRA OLIVEIRA
MADRID, 25 Sep. (EUROPA PRESS) –
Ancient pastoralist communities living in Angola’s Namib Desert region show unique genetic ancestry that delves into the ancestral groups of our species in Africa.
Africa is the birthplace of modern humans and the continent with the highest level of genetic diversity. While ancient DNA studies are revealing some aspects of Africa’s genetic structure before the expansion of food production, questions surrounding DNA preservation have limited the knowledge obtained from ancient DNA.
Hoping to find clues in modern populations, researchers from a Portuguese-Angolian TwinLab ventured into the Angolan Namib Desert, a remote, multi-ethnic region where different traditions met. The work is published in the journal Science Advances.
“We were able to locate groups that were thought to have disappeared more than 50 years ago,” says Jorge Rocha, a population geneticist at the Center for Research in Biodiversity and Genetic Resources (CIBIO, University of Porto), who led the field work, along with Angolan anthropologists Samuel and Teresa Aço from the Center for Desert Studies (CEDO).
Among the communities the team encountered were the Kwepe, a group of pastoralists who used to speak a language known as Kwadi. “Kwadi was a click language that shared a common ancestor with the Khoe languages spoken by foragers and herders throughout southern Africa,” he explains. it’s a statement Anne-Maria Fehn, a CIBIO linguist who participated in the fieldwork and was able to interview what could well be the last two Kwadi speakers.
“Khoe-Kwadi languages have been linked to a prehistoric migration of pastoralists from East Africa,” adds Rocha, whose research focuses on the population history of southern Africa.
Additionally, the team contacted Bantu-speaking groups that are part of the dominant pastoral tradition of southwestern Africa, as well as marginalized groups whose origins have been associated with a foraging tradition, distinct from that of the indigenous peoples. neighbors of the Kalahari, and whose original language was supposedly lost.
The team’s new study shows that the people of the Angolan Namib are quite divergent from other modern populations, but also very structured between them.
“Consistent with our previous studies on maternally inherited DNA, most genome diversity segregates by socioeconomic status. Many of our efforts focused on understanding to what extent this local variation and global eccentricity was caused by genetic drift. “A random process that disproportionately affects small populations and by mixing missing populations,” says Sandra Oliveira, a researcher at the University of Bern in Switzerland who worked with these populations during her PhD.
The team showed that, in addition to the high impact of genetic drift, which contributed to differences between neighboring groups of different socioeconomic statuses, the descendants of Kwadi speakers and the marginalized communities of the Namib Desert They retain a unique pre-Bantu ancestry found only in populations of the Namib Desert.
Mark Stoneking, who contributed to the first genome-wide studies of southern African foragers and participated in this study, says: “Previous studies revealed that Kalahari Desert foragers They descend from an ancestral population that was the first to separate from all other existing humans. Our results consistently place the newly identified ancestry within the same ancestral lineage, but suggest that the Namib-related ancestry diverged from all other southern African ancestry, followed by a division of northern and southern Kalahari ancestry.”
With this new information, the researchers were able to reconstruct on a large scale the contact histories that emerged from the migration of Khoe-Kwadi-speaking herders and Bantu-speaking farmers to southern Africa. Furthermore, the study demonstrates that modern DNA research targeting understudied regions of high ethnolinguistic diversity can complement ancient DNA studies to investigate the deep genetic structure of the African continent.
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