http://www.nature.com/ncomms/2014/141204/ncomms6692/full/ncomms6692.html
.... Analysis shows that the Khoisan and their ancestors have been the largest populations since their split with the non-Khoisan population ~100–150 kyr ago. In contrast, the ancestors of the non-Khoisan groups, including Bantu-speakers and non-Africans, experienced population declines after the split and lost more than half of their genetic diversity.