Subsistence strategy was the main factor driving population differentiation in the bidirectional corridor of the African Sahel

Abstract

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.

Sahelian pastoralism from the perspective of variants associated with lactase persistence

“…This phenomenon was revealed by both linguistic and ethnographic data (Braukämper, 1994; Manfredi, 2012; Owens, 1994), which indicate an incorporation of not only Fulani linguistic and cultural items but also individuals into the Arabic population. Our last study also revealed that this theory can be supported by genetics (Nováčková et al, 2020). The only slight disagreement between the various versions of Baggarization hypothesis lies in the dating and localization of the Arab‐Fulani contact.…”

“…Low genetic structure of the Sahel/Savannah belt, revealed by uniparental markers, inspired the notion of a bidirectional migration corridor situated between the Sahara and tropical rainforests (Černý et al, 2007; Černý et al, 2009; Černý et al, 2011). Other studies, however, stress the importance of pastoralism as a barrier of gene flow (Bučková, Černý, & Novelletto, 2013; Kleisner et al, 2019; Nováčková et al, 2020; Shriner & Rotimi, 2018). In fact, a high degree of endogamy can be observed among the Fulani pastoralists even today (Hampshire & Smith, 2001), especially in fully nomadic groups such as Wodaade (sing.…”

“…The aim of this article is to fill this gap in our knowledge and gain a deeper understanding of the history of (Fulani) pastoralism in sub‐Saharan Africa by providing new data for LP variants from 31 Sahelian, mostly Fulani, populations. Thanks to such a large LP dataset, we can also test hypotheses regarding their mutual prehistorical contacts and past gene flow between nomadic pastoralists and sedentary farmers in the Sahel/Savannah belt previously indicated by the results of studies on uniparental markers (Černý et al, 2011; Čížková et al, 2017; Nováčková et al, 2020).…”

“…Population genetic studies show that the African Sahel/Savannah belt formed a bidirectional corridor of human migrations between western and eastern Africa, with Lake Chad acting as a “center of gravity,” where, in the course of the Holocene, new haplogroups emerged and diversified and where the subsistence pattern had a more significant impact on population structure than linguistic affiliation (Černý et al, 2009; Černý et al, 2011; Černý, Salas, Hájek, Žaloudková, & Brdička, 2007; Nováčková et al, 2020; Podgorná, Soares, Pereira, & Černý, 2013). The origins of food production strategies in the Sahel/Savannah belt are not yet understood in detail but archeological investigations show that the first food‐producers in this area were pastoralists coming from the Sahara at ~5 ka (Ozainne, 2013).…”

Demographic history was a formative mechanism of the genetic structure for the taste receptor TAS2R16 in human populations inhabiting Africa's Sahel/Savannah Belt

“…The aim of this study is to contribute to our understanding of the evolution of bitter taste perception encoded by the TAS2R16 gene in populations across the still understudied region of the Sahel/Savannah belt, where both linguistic and archeological evidence shows that two modes of subsistence featuring different food production strategies have been coexisting for several millennia (Ehret, 2002(Ehret, , 2014Ozainne et al, 2014). Nowadays, this immense region, which can be geographically divided into western, central (Lake Chad Basin), and eastern parts is inhabited by Niger-Congo, Afro-Asiatic, and Nilo-Saharan populations and it has been shown that subsistence mode significantly contributed to its population structure (Novác ˇková et al, 2020).…”