OBJECTIVES: The Sahel belt is occupied by populations who use two types of subsistence strategy, nomadic pastoralism and sedentary farming, and who belong to three linguistic families, Niger-Congo, Nilo-Saharan, and Afro-Asiatic. Little is known, however, about the origins of these two populations and their mutual genetic relationships. MATERIALS AND METHODS: We have built a large dataset of mitochondrial DNA sequences and Y chromosomal STR haplotypes of pastoralists and farmers belonging to all three linguistic phyla in the western, central, and eastern parts of the Sahel. We calculated pairwise genetic, geographic, and linguistic distances between populations and analyzed the effects of geography, language, and subsistence on population genetic structure. RESULTS: We found that subsistence mode significantly contributed to the generally low population structure in the Sahel and that language affiliation plays a more important role for pastoralists than for farmers. We also demonstrated that geographic isolation significantly influenced the population structure of sedentary farmers but not of nomadic pastoralists. Finally, we found haplotypes shared between the Fulani and Arabic-speaking Baggara, supporting the theory of Baggarization, which explains the recent adaptation of Arabic-speaking nomads in the Sahel region through contact with autochthonous sub-Saharan populations. CONCLUSIONS: Based on various genetic and archaeological evidence pertaining to the Sahel, we suggest that the idea of a bidirectional Sahelian corridor is valid, but that pastoralists made a more important contribution to its population structure. It is also possible that agropastoralists diverged into farmers and pastoralists in the early stages of formation of the Sahelian gene pool.

Arabic Department Faculty of Arts University of Kordofan Al Ubayyid Sudan

Archaeogenetics Laboratory Institute of Archaeology of the Academy of Sciences of the Czech Republic Prague Czech Republic

Department of Forensic Genetics Institute of Criminalistics Prague Czech Republic

Department of Zoology Faculty of Science University of South Bohemia České Budějovice Czech Republic

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Population history and admixture of the Fulani people from the Sahel

A Population Genetic Perspective on Subsistence Systems in the Sahel/Savannah Belt of Africa and the Historical Role of Pastoralism

Demographic and Selection Histories of Populations Across the Sahel/Savannah Belt

Circum-Saharan Prehistory through the Lens of mtDNA Diversity