Genetic variation reveals large-scale population expansion and migration during the expansion of Bantu-speaking peoples

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.

Bantu expansion shows that habitat alters the route and pace of human dispersals

“…date for node 1 can be compared with the results from two recent genetic studies on the assumption that the in-group Bantu node coincides with the beginning of the Bantu expansion. Gignoux et al (24) report a population expansion of "sub-Saharan" people at ∼4,600 y ago, and Li et al (25) find evidence for a Bantu population expansion at ∼5,600 y ago.…”

Importance of human demographic history knowledge in genetic studies involving multi-ethnic cohorts

“…These languages are spoken by approximately one quarter of the SSA population (~200 million people) 14, 19 . The Bantu languages fall into this category, and consist of separate groups that constitute part of the Niger-Congo language phylum 20 .…”

“…We compared LWK to African populations from the 1000GP phase 3 (Yoruba (YRI) from Ibadan, Nigeria (n=108); Esan (ESN) from Nigeria (n=99); Mandika (GWD) from The Gambia (n=113); and the Mende (MSL) from Sierra Leone (n=85)) examining the same 193,634 variants, since these populations also speak the Niger-Kordofanian languages, and share recent genetic ancestry 12, 14 . The 1000GP call set was already filtered down using VCFtools (v 0.1.12b) and PLINK (v1.90b6.2), and only contained biallelic, non-singleton SNV sites that are a minimum of 2KB apart from each other and a minor allele frequency > 0.05 2, 15, 16 .…”

A Founder Mutation inMYO7AUnderlies a Significant Proportion of Usher Syndrome in Indigenous South Africans: Implications for the African Diaspora

“…31 The ''Bantu expansion'' refers to the movement of people approximately 5600 years ago, across and down Africa. Bantu speakers arrived in South Africa approximately 1500 years ago, where they diverged further.…”