The Fulani people, one of the most important pastoralist groups in sub-Saharan Africa, are still largely underrepresented in population genomic research. They speak a Niger-Congo language called Fulfulde or Pulaar and live in scattered locations across the Sahel/Savannah belt, from the Atlantic Ocean to Lake Chad. According to historical records, their ancestors spread from Futa Toro in the Middle Senegal Valley to Futa-Jallon in Guinea and then eastward into the Sahel belt over the past 1,500 years. However, the earlier history of this traditionally pastoral population has not been well studied. To uncover the genetic structure and ancestry of this widespread population, we gathered genome-wide genotype data from 460 individuals across 18 local Fulani populations, along with comparative data from both modern and ancient worldwide populations. This represents a comprehensive geographically wide-scaled genome-wide study of the Fulani. We revealed a genetic component closely associated with all local Fulani populations, suggesting a shared ancestral component possibly linked to the beginning of African pastoralism in the Green Sahara. Comparison to ancient DNA results also identified the presence of an ancient Iberomaurusian-associated component across all Fulani groups, providing additional insights into their deep genetic history. Additionally, our genetic data indicate a later Fulani expansion from the western to the eastern Sahel, characterized by a clinal pattern and admixture with several other African populations north of the equator.

• Keywords
• Africa, Fulani, Sahel, admixture, ancient DNA, genomics, migration, population structure,
• MeSH
• Black People * genetics   MeSH
• Ethnicity * genetics   MeSH
• Genome, Human MeSH
• Genotype MeSH
• Polymorphism, Single Nucleotide genetics   MeSH
• Humans MeSH
• Human Migration * history   MeSH
• Genetics, Population * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Africa South of the Sahara MeSH

This review focuses on the Sahel/Savannah belt, a large region of Africa where two alternative subsistence systems (pastoralism and agriculture), nowadays, interact. It is a long-standing question whether the pastoralists became isolated here from other populations after cattle began to spread into Africa (~8 thousand years ago, kya) or, rather, began to merge with other populations, such as agropastoralists, after the domestication of sorghum and pearl millet (~5 kya) and with the subsequent spread of agriculture. If we look at lactase persistence, a trait closely associated with pastoral lifestyle, we see that its variants in current pastoralists distinguish them from their farmer neighbours. Most other (mostly neutral) genetic polymorphisms do not, however, indicate such clear differentiation between these groups; they suggest a common origin and/or an extensive gene flow. Genetic affinity and ecological symbiosis between the two subsistence systems can help us better understand the population history of this African region. In this review, we show that genomic datasets of modern Sahel/Savannah belt populations properly collected in local populations can complement the still insufficient archaeological research of this region, especially when dealing with the prehistory of mobile populations with perishable material culture and therefore precarious archaeological visibility.

• Keywords
• Africa, Sahel/Savannah belt, archaeogenetics, pastoralism, population genetics, selection,
• MeSH
• Archaeology MeSH
• Humans MeSH
• Polymorphism, Genetic * MeSH
• Genetics, Population * MeSH
• Cattle MeSH
• Agriculture MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Cattle MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Geographicals
• Africa MeSH

The Sahel/Savannah belt harbors diverse populations with different demographic histories and different subsistence patterns. However, populations from this large African region are notably under-represented in genomic research. To investigate the population structure and adaptation history of populations from the Sahel/Savannah space, we generated dense genome-wide genotype data of 327 individuals-comprising 14 ethnolinguistic groups, including 10 previously unsampled populations. Our results highlight fine-scale population structure and complex patterns of admixture, particularly in Fulani groups and Arabic-speaking populations. Among all studied Sahelian populations, only the Rashaayda Arabic-speaking population from eastern Sudan shows a lack of gene flow from African groups, which is consistent with the short history of this population in the African continent. They are recent migrants from Saudi Arabia with evidence of strong genetic isolation during the last few generations and a strong demographic bottleneck. This population also presents a strong selection signal in a genomic region around the CNR1 gene associated with substance dependence and chronic stress. In Western Sahelian populations, signatures of selection were detected in several other genetic regions, including pathways associated with lactase persistence, immune response, and malaria resistance. Taken together, these findings refine our current knowledge of genetic diversity, population structure, migration, admixture and adaptation of human populations in the Sahel/Savannah belt and contribute to our understanding of human history and health.

• Keywords
• CNR1 gene, Africa, admixture, camel herders, pastoralists, population structure, selection,
• MeSH
• Black People MeSH
• Ethnicity genetics   MeSH
• Haplotypes MeSH
• Lactase genetics   MeSH
• Humans MeSH
• Genetics, Population * MeSH
• Gene Flow * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Lactase MeSH

African history has been significantly influenced by the Sahara, which has represented a barrier for migrations of all living beings, including humans. Major exceptions were the gene flow events that took place between North African and sub-Saharan populations during the so-called African Humid Periods, especially in the Early Holocene (11.5 to 5.5 thousand years ago), and more recently in connection with trans-Saharan commercial routes. In this study, we describe mitochondrial DNA (mtDNA) diversity of human populations from both sides of the Sahara Desert, i.e., both from North Africa and the Sahel/Savannah belt. The final dataset of 7213 mtDNA sequences from 134 African populations encompasses 470 newly collected and 6743 previously published samples, which were analyzed using descriptive methods and Bayesian statistics. We completely sequenced 26 mtDNAs from sub-Saharan samples belonging to the Eurasian haplogroup N1. Analyses of these N1 mitogenomes revealed their possible routes to the Sahel, mostly via Bab el-Mandab. Our results indicate that maternal gene flow must have been important in this circum-Saharan space, not only within North Africa and the Sahel/Savannah belt but also between these two regions.

• Keywords
• North Africa, Sahel/Savannah belt, mtDNA diversity, population history,
• MeSH
• Bayes Theorem MeSH
• Black People * MeSH
• Humans MeSH
• DNA, Mitochondrial * genetics   MeSH
• Gene Flow MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Africa, Northern MeSH
• Names of Substances
• DNA, Mitochondrial * MeSH