Genetic variation at twentythree microsatellite loci in sixteen human populations

We have analysed genetic variation at 23 microsatellite loci in a global sa mple of 16 ethnically and geographically diverse human populations. On the basis of their ancestral heritage and geographic locations, the studied pop ulations can be divided into five major groups, viz. African, Caucasian, As ian Mongoloid, American Indian and Pacific Islander. With respect to the di stribution of alleles at the 23 loci, large variability exists among the ex amined populations. However, with the exception of the American Indians and the Pacific Islanders, populations within a continental group show a great er degree of similarity. Phylogenetic analyses based on allele frequencies at the examined loci show that the first split of the present-day human pop ulations had occurred between the Africans and all of the non-African popul ations, lending support to an African origin of modern human populations. G ene diversity analyses show that the coefficient of gene diversity estimate d from the 23 loci is, in general, larger for populations that have remaine d isolated and probably of smaller effective sizes, such as the American In dians and the Pacific Islanders. These analyses also demonstrate that the c omponent of total gene diversity, which is attributed to variation between groups of populations, is significantly larger than that among populations within each group. The empirical data presented in this work and their anal yses reaffirm that evolutionary histories and the extent of genetic variati on among human populations can be studied using microsatellite loci.