The Fulbe are a pastoral ethnic group living in the Sahelian belt. Their large population size and broad geographic settlement, together with the complexity of their interactions with groups from Saharan and sub-Saharan Africa, make them a key population to understand the structure of human genetic variation in Africa. Whereas some aspects of their recent history are known, with documented evidence of their settlement in the Fouta Djallon Highlands (Guinea) during the XI century, their origins remain to be elucidated. Several hypotheses have been proposed, suggesting different African and non-African populations as possible ancestors of Fulbe. The genetic data collected so far did not help to address this question, since different loci lead to conflicting results. To shed new light on the origin and early history of Fulbe, we will analyse 50 high coverage (30×) whole genomes, including 30 Fulbe and 20 non-Fulbe subjects from neighbouring Sahelian groups and northern and eastern Africa. The data will be used to investigate the population structure and admixture events of Fulbe with other African and non-African people. We will reconstruct the ancestry profile of the Fulbe genomes, both at the individual and chromosomal level, taking also into account the data available for ancient African samples. Differently from previous studies which focused on broad areas with few individuals per group or on genome-wide single nucleotide polymorphisms (SNPs), our proposed research project relies on whole genome sequencing of several individuals from the same ethnic group. By this approach, we expect to obtain important new results about the Fulbe genomic history and their ancient and recent relations with other populations.
To date, the number of African individuals in genomic research projects is much less than the number of individuals of European ancestry [57,58]. Interestingly, the few high coverage African whole genomes that have been produced so far show that African people have a larger amount of genetic variants compared to other populations [27,31,33,59], an evidence in line with data from other nuclear and uniparental genetic polymorphisms.
Genomic studies analysed several African populations, often with few individuals in each group: this approach allowed the description of the general variability of the region under study, but it gave only small clues about the history of each specific ethnic group. On the other hand, genome-wide SNP studies focused on one or few African populations [18,60]; although the analysis of SNPs is cost effective and the newest arrays include millions of SNPs densely and evenly distributed along the genome, this approach still presents some caveats. Indeed, most of the commercially available arrays rely on variants known to be polymorphic in the European populations, thus suffering from an ascertainment bias, well known in population genetics [61], that should be taken into account before running downstream analyses [62,63]. WGS approach minimizes ascertainment bias and is more informative for some downstream analyses, such as the evaluation of LD structure [64] and the selection tests based on the skew in the allele frequency spectrum [65,66].
Differently from previous studies [18,60], we proposed a WGS project focused on a specific African population, the Fulbe, including several individuals belonging to this ethnic group and sampled in 8 different Sahelian countries. Since Fulbe are a nomadic ethnic group, the analysis of neighbouring people is of crucial importance to understand their history, so we will also select individuals from non-Fulbe Sahelian people. Furthermore, since a northern or eastern African origin of Fulbe has been previously suggested, we will also include non-Fulbe individuals from these regions. Our sampling strategy and the powerful WGS approach will allow us to shed light on the ancient history of the Fulbe population and to dig deeper into their demographic history and of the African continent in general.
The full list of bibliographic references is reported at the end of the following section.