Abstract
Human Y chromosomes belonging to the haplogroup R1b1-P25, although very common in Europe, are usually rare in Africa. However, recently published studies have reported high frequencies of this haplogroup in the central-western region of the African continent and proposed that this represents a 'back-to-Africa' migration during prehistoric times. To obtain a deeper insight into the history of these lineages, we characterised the paternal genetic background of a population in Equatorial Guinea, a Central-West African country located near the region in which the highest frequencies of the R1b1 haplogroup in Africa have been found to date. In our sample, the large majority (78.6%) of the sequences belong to subclades in haplogroup E, which are the most frequent in Bantu groups. However, the frequency of the R1b1 haplogroup in our sample (17.0%) was higher than that previously observed for the majority of the African continent. Of these R1b1 samples, nine are defined by the V88 marker, which was recently discovered in Africa. As high microsatellite variance was found inside this haplogroup in Central-West Africa and a decrease in this variance was observed towards Northeast Africa, our findings do not support the previously hypothesised movement of Chadic-speaking people from the North across the Sahara as the explanation for these R1b1 lineages in Central-West Africa. The present findings are also compatible with an origin of the V88-derived allele in the Central-West Africa, and its presence in North Africa may be better explained as the result of a migration from the south during the mid-Holocene.