We Swore These Human Populations Vanished 50 Years Ago. Scientists Just Found Them.

Tim Newcomb

POP SCI
Wed, September 27, 2023 

Found: Human Genetic Populations Once Thought Lost

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A research team was able to locate human populations in an African desert believed to have disappeared more than 50 years ago.

DNA studies helped show the genetic differences between neighboring groups of populations and how they changed over time.

Researching understudied regions of high ethnolinguistic diversity opens new avenues of knowledge.

Probing the deep genetic web of the African continent has revealed a deeply divergent ancestry among mixed populations in the Angolan Namib Desert. And that web certainly had some secrets to reveal, according to a recent study published in Science Advances.

“We were able to locate groups which were thought to have disappeared more than 50 years ago,” Jorge Rocha, one of the authors of the study, said in a news release.

The African continent has the highest level of genetic diversity in the world. But that diversity isn’t always clearly on display. It can be hard to tell one genetic population from another if the groups have become relatively intermixed, and if the outward signs of a population—like, say, their native languages—disappear, it can appear that the population itself is gone.

Often, clues to modern genetic populations are found by mining information from ancient DNA. But due to the natural decay of these samples, they paint an incomplete picture. In order to get the clearest possible understanding of the true genetic diversity of the Angolan Namib Desert, the team went in search of modern DNA samples that could supplement our ancient bank of genetic information.

In their search, the team located the Kwepe group, which once spoke the click language Kwadi. When evidence of the Kwadi language disappeared, researchers believed that the Kwepe were gone as well. But there they were, in the modern day. The team even found two individuals who could still speak Kwadi.

The team also contacted Bantu-speaking groups and other marginalized populations associated with foraging traditions whose original languages were previously believed lost.

“Previous studies revealed that foragers from the Kalahari Desert descend from an ancestral population who was the first to split from all other extant humans,” Mark Stoneking, a professor at the Max Plank Institute for Evolutionary Anthropology, said in a news release. “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 ancestries, followed by a split of northern and southern Kalahari ancestries.”

The study of these groups helps show that both genetic and linguistic differences can be associated with lifestyle variances. For example, the more different two populations lifestyles were—say, one was a pastoral group and the other was a hunter-gatherer group—the more their genetic makeup and linguistic expression seemed to differ. “A lot of our efforts were placed in understanding how much of this local variation and global eccentricity was caused by genetic drift,” Sandra Oliverira of the University of Bern said in a news release, “a random process that disproportionately affects small populations and by admixtures from vanished populations.”

The study authors said that studying ancient DNA can reveal the genetic structure of Africa before the expansion of the Bantu-speaking agriculturalists, but that understanding the potential impacts on the “genetic makeup of present-day African groups” from other potentially extinct societies “remain[s] elusive.”

By diving into the desert, the team located small-scale groups with ties to varying traditions, such as foraging and speaking Kwadi. They were then able to dissect ancestry into smaller groups and reconstruct the histories of emerging migration patterns. The team used this information to show a “deeply divergent ancestry” in groups from the Angolan Namib region.

This kind of detailed population analysis helps to reconstruct the histories and migration of southern African people—for example, the team saw how Khoe speakers mixed with the Kalahari people earlier than the Bantu speakers arrived—and demonstrates the value in modern DNA research.

“The unique genetic heritage of the Namib peoples shows how modern DNA research targeting understudied regions of high ethnolinguistic diversity,” the authors wrote, “can complement ancient DNA studies in probing the deep genetic structure of the African continent.”