title: Origins and genetic diversity of pygmy hunter-gatherers from Western Central Africa.
abstract: Central Africa is currently peopled by numerous sedentary agriculturalist populations neighboring the largest group of mobile hunter-gatherers, the Pygmies [1-3]. Although archeological remains attest to Homo sapiens' presence in the Congo Basin for at least 30,000 years, the demographic history of these groups, including divergence and admixture, remains widely unknown [4-6]. Moreover, it is still debated whether common history or convergent adaptation to a forest environment resulted in the short stature characterizing the pygmies [2, 7]. We genotyped 604 individuals at 28 autosomal tetranucleotide microsatellite loci in 12 nonpygmy and 9 neighboring pygmy populations. We found a high level of genetic heterogeneity among Western Central African pygmies, as well as evidence of heterogeneous levels of asymmetrical gene flow from nonpygmies to pygmies, consistent with the variable sociocultural barriers against intermarriages. Using approximate Bayesian computation (ABC) methods [8], we compared several historical scenarios. The most likely points toward a unique ancestral pygmy population that diversified approximately 2800 years ago, contemporarily with the Neolithic expansion of nonpygmy agriculturalists [9, 10]. Our results show that recent isolation, genetic drift, and heterogeneous admixture enabled a rapid and substantial genetic differentiation among Western Central African pygmies. Such an admixture pattern is consistent with the various sociocultural behaviors related to intermariages between pygmies and nonpygmies.
authors.affiliation: Ecoanthropology and Ethnobiology, UMR, CNRS-MNHN-Université Paris, France. verdu@mnhn.fr
authors.forename: Paul
authors.initials: P
authors.lastname: Verdu
authors.forename: Frederic
authors.initials: F
authors.lastname: Austerlitz
authors.forename: Arnaud
authors.initials: A
authors.lastname: Estoup
authors.forename: Renaud
authors.initials: R
authors.lastname: Vitalis
authors.forename: Myriam
authors.initials: M
authors.lastname: Georges
authors.forename: Sylvain
authors.initials: S
authors.lastname: Théry
authors.forename: Alain
authors.initials: A
authors.lastname: Froment
authors.forename: Sylvie
authors.initials: S
authors.lastname: Le Bomin
authors.forename: Antoine
authors.initials: A
authors.lastname: Gessain
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Hombert
authors.forename: Lolke
authors.initials: L
authors.lastname: Van der Veen
authors.forename: Lluis
authors.initials: L
authors.lastname: Quintana-Murci
authors.forename: Serge
authors.initials: S
authors.lastname: Bahuchet
authors.forename: Evelyne
authors.initials: E
authors.lastname: Heyer
mesh_terms: D000350:Africa, Central; D000354:Africa, Western; D001499:Bayes Theorem; D001519:Behavior / Q000502:physiology*; D044383:Black People / Q000235:genetics*; D040961:Genetic Drift; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D010641:Phenotype; D017422:Sequence Analysis, DNA