 South Asian populations have the highest STR diversity within R1a1a, and subsequent older TMRCA datings, and R1a1a is present among both higher (Brahmin) castes and lower castes, although the presence is higher among Brahmin castes.From these findings some researchers have concluded that R1a1a originated in South Asia, excluding a substantial genetic influx from Indo-European migrants.However, this diversity, and the subsequent older TMRCA-datings, can also be explained by the historically high population numbers, which increases the likelihood of diversification and microsatellite variation.