Viswanathan et al. (2004) in a study on genetic structure and affinities among tribal populations of southern India concludes, ""Genetic differentiation was high and genetic distances were not significantly correlated with geographic distances. Genetic drift therefore probably played a significant role in shaping the patterns of genetic variation observed in southern Indian tribal populations." Otherwise, analyses of population relationships showed that all Indian and South Asian populations are still similar to one another, regardless of phenotypic characteristics, and do not show any particular affinities to Africans. We conclude that the phenotypic similarities of some Indian groups to Africans "do not" reflect a close relationship between these groups, but are better explained by "convergence"."