The Bantu expansion changed Africa. Scientists are still tracing how.

By the 1990s, however, some scholars began to question the idea that Bantu languages and skills spread through a migration. Couldn’t these cultural habits have spread while people stayed in the same place, with hunter gatherer communities passing along new technologies, languages, and habits to each other?

Genetic techniques that could analyze people’s ancestry helped to resolve that debate. All of us share DNA with our relatives: 50 percent on average with siblings, 12.5 percent with cousins, 3.3 percent with second cousins, and so on. Though these proportions become minute the further back in time a shared common ancestor lived, statistical techniques can tease out patterns.

Sure enough, a 2009 genetic analysis of 2,432 Africans found that Bantu-speaking people from western, central, and southern Africa are much more closely related than one might expect given their geographic distance. And in 2024, a team of scientists analyzed the genomes of 1,763 Africans and found the greatest genetic diversity among Bantu speakers in western Africa. As distance from the region increased, diversity declined. “This is a typical signature of a population expanding from one place to another,” explains coauthor Carina Schlebusch, a geneticist at Uppsala University in Sweden.

Roughly 350 million people across sub-Saharan Africa speak one of roughly 500 Bantu languages—from Swahili in eastern Africa to Xhosa spoken in southern Africa.

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Mysterious roots

But while linguistic and genetic data point to western Africa—particularly the Grassfields region of Cameroon—as the Bantu homeland, conclusive archaeological proof is thin. At the best-studied archaeological site in the Grassfields, a rock shelter called Shum Laka, pottery fragments appear dating from 7,000 to 6,000 years ago and become abundant by 5,000 to 4,000 years ago. Bowls and jars at first decorated simply with incisions and stamps and later bearing the marks of carved or braided tools rolled over wet clay are a possible, yet inconclusive, trace of Bantu ancestors.

South of Cameroon, archaeologists have searched for artifacts in one of the Bantu-speaking people’s first destinations: the Congo rainforest. A handful of times between 2010 and 2023, archaeologist Alexandre Livingstone Smith of Belgium’s Royal Museum for Central Africa traveled via boat along the Congo River as part of a team led by linguist Birgit Ricquier. In a number of villages, Smith found pottery shards of a style consistent with that found farther west, dating back to 2,300 to 2,000 years ago. “That would be the potential first Bantu settlers of the forest,” Smith says.