Thanks to deep knowledge of Serge Bahuchet on Pygmies, in 2003 we have launched an interdisciplinary project on Central Africa for the study of the Pygmy populations and their neighbours (ACI - Prosodie).
Central Africa is currently peopled by numerous sedentary agriculturalist populations neighbouring the largest group of mobile hunter-gatherers : the African pygmies. 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. Morover, it is still debated whether common history or convergent adaptation to forest environment resulted in the specific morphological traits (including short stature) shared by all pygmies. We have first compared the mitochondrial DNA from one western and one eastern populations in order to infer a common maternal origin of eastern and western Pygmies. (Quintana et al, PNAS, 2008)
Then we have focused on a detailed study on the diversity of Pygmies populations and their interactions with neighbouring populations in Western Central Africa.
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, we compared several historical scenarios. The most likely points toward a unique ancestral pygmy population that diversified 2800 years ago, contemporarily with the Neolithic expansion of nonpygmy agriculturalists. 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. This highlights the major influence of sociological behaviour on human biological evolution. (Verdu et al, Current Biology, 2009)
In collaboration with Pasteur Institute, using resequencing data, we were able to confirm the split age between Pygmies and non-Pygmies around 50000yrs (Patin et al, 2009 : Patin E, Laval G, Barreiro LB, Salas A, Semino O, Santachiara-Benerecetti S, Kidd KK, Kidd JR, Van der Veen L, Hombert JM, Gessain A, Froment A, Bahuchet S, Heyer E, Quintana-Murci L. Inferring the demographic history of African farmers and pygmy hunter-gatherers using a multilocus resequencing data set. 2009 Plos Genetics).
At a more regional scale, we also demonstrated that despite a high mobility, Pygmies indeed have a small range of dispersion. Verdu et al, 2010 : Verdu P, Leblois R, Froment A, Théry S, Bahuchet S, Rousset F, Heyer E, Vitalis R Limited dispersal in mobile hunter-gatherer Baka Pygmies. Biol Lett. 2010 Apr 28