Abstract
The majority of sub-Saharan Africans today speak a number of closely related languages collectively referred to as ‘Bantu’ languages. The current distribution of Bantu-speaking populations has been found to largely be a consequence of the movement of people rather than a diffusion of language alone. Linguistic and single marker genetic studies have generated various hypotheses regarding the timing and the routes of the Bantu expansion, but these hypotheses have not been thoroughly investigated. In this study, we re-analysed microsatellite markers typed for large number of African populations that—owing to their fast mutation rates—capture signatures of recent population history. We confirm the spread of west African people across most of sub-Saharan Africa and estimated the expansion of Bantu-speaking groups, using a Bayesian approach, to around 5600 years ago. We tested four different divergence models for Bantu-speaking populations with a distribution comprising three geographical regions in Africa. We found that the most likely model for the movement of the eastern branch of Bantu-speakers involves migration of Bantu-speaking groups to the east followed by migration to the south. This model, however, is only marginally more likely than other models, which might indicate direct movement from the west and/or significant gene flow with the western Branch of Bantu-speakers. Our study use multi-loci genetic data to explicitly investigate the timing and mode of the Bantu expansion and it demonstrates that west African groups rapidly expanded both in numbers and over a large geographical area, affirming the fact that the Bantu expansion was one of the most dramatic demographic events in human history.
Highlights
With the end of the cold Younger Dryas period and the onset of the Holocene epoch around 10 thousand years ago, the re-establishment of warm conditions led to increases in human population densities throughout the world [1,2]
We interrogate genetic data to better understand the spread of the west African genetic component that accompanied the expanding Bantu-speaking people, from the region that the Bantu expansion is postulated to have started from (Nigeria and Cameroon), throughout the rest of the African continent
The distinct clusters for these three different additional African linguistic groups became apparent as the number of assumed clusters (K) increased but the west African genetic component remains present in many populations and areas of the African continent
Summary
With the end of the cold Younger Dryas period and the onset of the Holocene epoch around 10 thousand years ago (kya), the re-establishment of warm conditions led to increases in human population densities throughout the world [1,2]. The population increase coincides with the invention of agriculture, which was independently developed in several geographically dispersed regions [1]. One such region was west-central Africa where the first traces of archaeological artefacts that might be linked to farming practices started to appear around 7 kya [2]. In temperate regions, farming societies generally out-competed hunter–gatherer societies, and farming populations expanded very quickly. Within west Africa, the expansions and dispersals of farming populations had begun by approximately 5 kya [3,4]. The traces of the expanding west African farmers remains today in the distribution of languages, cultural practices and genetic variants across most sub-Saharan African populations
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