Rito T, Richards MB, Fernandes V, Alshamali F, Cerny V, Pereira L, Soares P., "The first modern human dispersals across Africa", PLoS One 2013 Nov 13; 8(11):e80031. doi:10.1371/journal.pone.0080031. "By ~130 ka two distinct groups of anatomically modern humans co-existed in Africa: broadly, the ancestors of many modern-day Khoe and San populations in the south and a second central/eastern African group that includes the ancestors of most extant worldwide populations. Early modern human dispersals correlate with climate changes, particularly the tropical African “megadroughts” of MIS 5 (marine isotope stage 5, 135–75 ka) which paradoxically may have facilitated expansions in central and eastern Africa, ultimately triggering the dispersal out of Africa of people carrying haplogroup L3 – 60 ka. Two south to east migrations are discernible within haplogroup L0. One, between 120 and 75 ka, represents the first unambiguous long-range modern human dispersal detected by mtDNA and might have allowed the dispersal of several markers of modernity. A second one, within the last 20 ka signalled by L0d, may have been responsible for the spread of southern click-consonant languages to eastern Africa, contrary to the view that these eastern examples constitute relics of an ancient, much wider distribution."
