is associated with the distribution of “later Iron Age” sites in central and southern Africa (Phillipson, 1976).

There is also a genetic signature of past population movements thought to be associated with the Bantu expansion. The large majority of genetic analyses have focused on mtDNA and NRY data. Overall, both datasets tie particular mtDNA (e.g., L0a, L2a, L3b, and L3e) (Pereira et al., 2001; Salas et al., 2002, Plaza et al., 2004; Beleza et al., 2005; Wood et al., 2005; Quintana-Murci et al., 2008) and NRY [e.g., E3a (M2/M180), E2 (M75), and B2a (M150)] (Beleza et al., 2005; Henn et al., 2008; Berniell-Lee et al., 2009) lineages to the Bantu expansion, because they are found in the highest frequencies in extant Bantu-speaking populations. Interestingly, comparative studies of mtDNA and NRY variation suggest different maternal and paternal population histories related to the Bantu expansion (Beleza et al., 2005; Wood et al., 2005). Specifically, NRY variation in regions affected by the Bantu expansion is low relative to mtDNA variation and consists almost exclusively of haplogroup lineages associated with the Bantu expansion (Wood et al., 2005). Conversely, the mtDNA haplogroup lineages in the same samples include lineages associated with the Bantu expansion as well as lineages that are thought to have been present in the region before the Bantu expansion (Tishkoff et al., 2007a). This discrepancy is largely attributed to sex-biased migration and gene flow due to the practice of patrilocality and/or polygyny (Wood et al., 2005; Pilkington et al., 2008), both of which are common in present-day Bantu-speaking populations. Moreover, this pattern of sex-biased gene flow is documented independently in other regions of the world such as the Pacific Islands (Scheinfeldt et al., 2006; Friedlaender et al., 2008). Both loci, however, are more susceptible to genetic drift than autosomal loci because of their relatively smaller effective population sizes; therefore, some of the differential male/female patterns may be attributed to chance. A recent analysis of genome-wide autosomal data is consistent with a large genetic impact of the Bantu expansion on most of sub-Saharan Africa, as evidenced by the presence of Niger-Kordofanian ancestry in many central, eastern, and southern African populations (Tishkoff et al., 2009). In addition, Tishkoff et al. (2009) documented evidence from their analysis of genome-wide autosomal loci of a distinct Bantu migration from eastern to southern Africa, which is consistent with the archaeological and linguistic evidence of dispersal of Bantu technology and languages from the Great Lakes region of East Africa (Ehret, 2001).