Even if the age of the most recent common ancestor of -13,915*G is ∼4 ka as shown in a previous study, our results suggest that its spread to Africa was more recent, which is consistent with the migrations of Arabic tribes. Because the incidence of sub-Saharan mtDNA haplotypes is negatively correlated with the occurrence of -13,915*G, we suggest that the decrease of its frequency in Africa has been caused by progressive admixture of the Arabian nomads with sub-Saharan populations.

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.

No abstract

It is suggested that contemporary Fulani pastoralists might be descendants of an ancestral Eastern African population that, while crossing the Sahara in the Holocene, admixed slightly with a population of Eurasian (as evidenced by uniparental polymorphisms) ancestry. It seems that, in the Fulani pastoralists, Alu elements reflect more ancient genetic relationships than do uniparental genetic systems.

No abstract