(2013) found that patterns of diversity in African R1b-V88 did not fit with a movement of Chadic-speaking people from the North across the Sahara to West-Central Africa, but was compatible with the reverse, an origin of the V88 lineages in Central-West Africa, followed by migration to North Africa.R1b1a2a is a sub-clade of R-V88, which is defined by the presence of SNP marker M18.