A Bidirectional Corridor in the Sahel-Sudan Belt and the Distinctive Features of the Chad Basin Populations: A History Revealed by the Mitochondrial DNA Genome
The Chad Basin was sparsely inhabited during the Stone Age, and its continual settlement began with the Holocene. The role played by Lake Chad in the history and migration patterns of Africa is still unclear. We studied the mitochondrial DNA (mtDNA) variability in 448 individuals from 12 ethnically and/or economically (agricultural/pastoral) different populations from Cameroon, Chad, Niger and Nigeria. The data indicate the importance of this region as a corridor connecting East and West Africa; however, this bidirectional flow of people in the Sahel-Sudan Belt did not erase features peculiar to the original Chad Basin populations. A new sub-clade, L3f2, is described, which together with L3e5 is most probably autochthonous in the Chad Basin. The phylogeography of these two sub-haplogroups seems to indicate prehistoric expansion events in the Chad Basin around 28,950 and 11,400 Y.B.P., respectively. The distribution of L3f2 is virtually restricted to the Chad Basin alone, and in particular to Chadic speaking populations, while L3e5 shows evidence for diffusion into North Africa at about 7,100 Y.B.P. The absence of L3f2 and L3e5 in African-Americans, and the limited number of L-haplotypes shared between the Chad Basin populations and African-Americans, indicate the low contribution of the Chad region to the Atlantic slave trade.
Document Type: Research Article
Affiliations: 1: Unidad de Genética, Instituto de Medicina Legal, Facultad de Medicina, Universidad de Santiago de Compostela, 15782, and Centro Nacional de Genotipado (CeGen), Hospital Clínico Universitario, 15706, Galicia, Spain 2: Department of Anthropology & Environment, Institute of Archaeology, Czech Academy of Sciences, 118 01 Prague 1, Czech Republic 3: Accredited Laboratory for DNA Testing and Co-ordination Centre of Genetic Laboratories in the Czech Republic, Institute of Haematology and Blood Transfusion, 128 20 Prague 2, Czech Republic
Publication date: July 1, 2007