Features of Evolution and Expansion of Modern Humans, Inferred from Genomewide Microsatellite Markers

Lev A. Zhivotovsky,1 Noah A. Rosenberg,2 and Marcus W. Feldman3

1Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow; 2Program in Molecular and Computational Biology, University of Southern California, Los Angeles; and 3Department of Biological Sciences, Stanford University, Stanford, CA

Received December 9, 2002; accepted for publication February 20, 2003; electronically published April 10, 2003.

We study data on variation in 52 worldwide populations at 377 autosomal short tandem repeat loci, to infer a demographic history of human populations. Variation at di-, tri-, and tetranucleotide repeat loci is distributed differently, although each class of markers exhibits a decrease of within-population genetic variation in the following order: sub-Saharan Africa, Eurasia, East Asia, Oceania, and America. There is a similar decrease in the frequency of private alleles. With multidimensional scaling, populations belonging to the same major geographic region cluster together, and some regions permit a finer resolution of populations. When a stepwise mutation model is used, a population tree based on TD estimates of divergence time suggests that the branches leading to the present sub-Saharan African populations of hunter-gatherers were the first to diverge from a common ancestral population (71142 thousand years ago). The branches corresponding to sub-Saharan African farming populations and those that left Africa diverge next, with subsequent splits of branches for Eurasia, Oceania, East Asia, and America. African hunter-gatherer populations and populations of Oceania and America exhibit no statistically significant signature of growth. The features of population subdivision and growth are discussed in the context of the ancient expansion of modern humans.