Microsatellite loci and the origin of modern humans: A Bayesian analysis

Microsatellite loci have recently been used to date the migration Out-of-Africa of early modern humans. In this paper, an extension of the stepwise model (Zhivotovsky and Feldman 1995) is used to build a Bayesian hierarchical model for microsatellite data sampled from African and non-African populations. The prior information induced by the assumptions contained in the stepwise model is exploited to obtain the estimate of the time since the migration Out-of-Africa. The results obtained using our Bayesian model suggest that the original African populations that eventually made up the other populations could have comprised about 20,000-50,000 individuals and of these less than 15% could have migrated Out-of-Africa. The event of divergence can be dated to 100,000-300,000 years ago.