title: Ancestral stories of Ghanaian Bimoba reflect millennia-old genetic lineages.
abstract: Oral history and oral genealogies are mechanisms of collective memory and a main cultural heritage of many populations without a writing system. In the effort to analytically address the correspondence between genetic data and historical genealogies, anthropologists hypothesised that genealogies evolve through time, ultimately containing three parts: literal--where the most recent ancestry is truthfully represented; intended--ancestry is inferred and reflects political relations among groups; and mythical--that does not represent current social reality. While numerous studies discuss oral genealogies, to our knowledge no genetic studies have been able to investigate to what extent genetic relatedness corresponds to the literal and intended parts of oral genealogies. We report on the correspondence between genetic data and oral genealogies among Bimoba males in a single village in North-Eastern Ghana. We compared the pairwise mismatch distribution of Y chromosome short tandem repeat (Y-STR) haplotypes among all lineages present in this village to the self-reported (oral) relatedness. We found that Bimoba are able to correctly identify unrelated individuals in 92% of the cases. In contrast, they are able to correctly identify related individuals only in 38% of the cases, which can be explained by three processes: (1) the compression of genealogies, leading to increasing inaccuracy with increasing genealogical distance, (2) inclusions into the lineage from intended relations such as clan co-option or adoptions, and (3) false paternities, which in this study were found to have a minor effect on the correspondence between genetic data and oral genealogies. In addition, we observed that 70% of unrelated pairs have from six to eight Y-STR differences, a diversification peak which we attribute to an ancient West African expansion dating around 9454 years ago. We conclude that, despite all caveats, oral genealogies are reflecting ancient lineages more accurately than previously thought.
authors.affiliation: Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Hernando
authors.initials: H
authors.lastname: Sanchez-Faddeev
authors.forename: Jeroen
authors.initials: J
authors.lastname: Pijpe
authors.forename: David
authors.initials: D
authors.lastname: van Bodegom
authors.forename: Tom
authors.initials: T
authors.lastname: van der Hulle
authors.forename: Kristiaan J
authors.initials: KJ
authors.lastname: van der Gaag
authors.forename: Ulrika K
authors.initials: UK
authors.lastname: Eriksson
authors.forename: Thomas
authors.initials: T
authors.lastname: Spear
authors.forename: Rudi G J
authors.initials: RG
authors.lastname: Westendorp
authors.forename: Peter
authors.initials: P
authors.lastname: de Knijff
mesh_terms: D041322:Chromosomes, Human, Y / Q000235:genetics*; D003469:Culture; D005006:Ethnicity / Q000235:genetics*; D005789:Genealogy and Heraldry; D005869:Ghana; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics