DNA, Pottery and 500 Languages Trace Africa’s Great Bantu Migration

Around 350 million people in Africa today speak one of roughly 500 Bantu languages, and genetic studies of thousands of Africans now show that this spread was driven by people on the move: farmers and ironworkers who left western Africa between 6,000 and 4,000 years ago and gradually settled the southern half of the continent.

A feature in Ars Technica brings together the linguists, archaeologists and geneticists reconstructing what is one of the largest and longest human migrations in history. Many questions remain open, but several recent studies have narrowed down where the journey began and the route it took.

Iron furnaces that ran without bellows

One visible legacy of the migration is Great Zimbabwe, the stone-walled capital of a southern African kingdom that flourished from 1000 to 1700 AD. Near its ruins, clusters of iron-smelting furnaces survive as heaps of rubble. At Mashava, a village 25 miles northwest of the city, some clay fragments still carry the fingermarks of the people who smoothed the furnace walls.

The furnaces had to withstand more than 2,100° Fahrenheit. Instead of relying on workers pumping bellows, they drew air in and pushed it out through a chimney on their own, a method called natural draft. Ezekiel Mtetwa, an archaeometallurgist at Chicago’s Field Museum of Natural History, told Ars Technica the furnaces point to iron production that was both intensive and technically advanced. The iron became hoes, axes and arrowheads.

How scientists know people moved

Linguists first noticed how similar Bantu languages are. The name comes from the plural of muntu, which means “human being” in many of them. Western Africa has the greatest variety of Bantu languages, which is what researchers expect from the place a language family started.

Archaeologists then found pottery, village remains, metalworking, livestock and western African crops appearing across eastern and southern Africa within the last 2,000 years, with northern sites generally older than southern ones. By the 1990s, some scholars argued that the languages and skills could have spread from group to group without anyone migrating.

Genetics settled much of that debate. A 2009 analysis of 2,432 Africans found that Bantu speakers in western, central and southern Africa are far more closely related than their distances apart would suggest. In 2024, a team that analyzed the genomes of 1,763 Africans found the highest genetic diversity among Bantu speakers in western Africa, falling off with distance. Uppsala University geneticist Carina Schlebusch, a coauthor, called this the typical signature of a population expanding outward.

One route through the rainforest

Linguistic and genetic data point to the Grassfields region of Cameroon as the homeland, though archaeological proof there is thin. At the Shum Laka rock shelter, pottery appears from 7,000 to 6,000 years ago and becomes common by 5,000 to 4,000 years ago, a possible but unconfirmed trace of early Bantu speakers. Along the Congo River, archaeologist Alexandre Livingstone Smith of Belgium’s Royal Museum for Central Africa found pottery dating to 2,300 to 2,000 years ago on trips between 2010 and 2023, which he said could belong to the first Bantu settlers of the forest.

Evidence now favors a single crossing of the Congo rainforest, with groups splitting into eastern and southern streams only at its southern edge, roughly 2,500 to 3,500 years ago. A 2015 computer analysis of about 400 Bantu languages found the deepest splits among rainforest languages. In a 2023 study, University of Leicester geneticist Sandra Beleza and colleagues found that genomes from Mozambique in eastern Africa were closer to those from Angola than to any samples from Cameroon.

Mixing with hunter-gatherers

The 2024 study also found that some central African Bantu-speaking groups carry about an eighth of their DNA from rainforest hunter-gatherers, and some southern groups share a similar amount with Khoisan peoples. A 2021 study of southern African Bantu speakers found more Khoisan ancestry than expected in mitochondrial DNA, which passes from mothers, and much more Bantu ancestry on Y chromosomes, which pass from fathers. That pattern suggests mostly Bantu men pairing with Khoisan women, though the reasons are speculation.

What’s still unclear

Researchers still do not know when or how Bantu speakers picked up farming and metalworking, or whether they invented iron smelting or learned it from neighbors. Scientists in the field cite sparse written records and limited research funding as obstacles.

Why it matters

The migration reshaped the population of sub-Saharan Africa, according to Beleza. At least as many Africans as speak Bantu languages carry Bantu ancestry, as do many African Americans and Afro-Latinos, so the work traces the deep family history of a very large share of people living today.

Source: Ars Technica