The analysis of variation of mtDNA hypervariable region 1 suggests that Eastern and Western Pygmies diverged before the Bantu expansion

The Eastern Pygmies from Zaire and Western Pygmies from Cameroon, Congo, and the Central African Republic represent the two principal groups of African Pygmies. In the "recent divergence" hypothesis in which Western Pygmies are thought to be the result of hybridization between the ancestors of Eastern Pygmies and Bantu farmers who penetrated the equatorial belt and came into contact with Pygmies around 2-3 kiloyears ago. On the basis of recent archaeological research in the tropical rain forest, we propose a "pre-Bantu divergence" hypothesis, which posits the separation between the ancestors of Eastern and Western Pygmies earlier than 18 kiloyears ago. In order to test the two hypotheses, we analyzed the variation of the hypervariable region I of the mitochondrial DNA in the Mbenzele, Western Pygmies of the Central African Republic, and compared our results with those of previous mtDNA and Y chromosome studies. Distribution, sequence variation, and age of haplogroups along with genetic distances among populations, estimates of divergence times, and simulations based on the coalescent approach were found to be congruent with the pre-Bantu divergence but failed to support the recent divergence hypothesis.