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Abstract
Archeological and paleontological evidences point to East Africa as the likely area of early evolution of modern humans. Genetic studies also indicate that populations from the region often contain, but not exclusively, representatives of the more basal clades of mitochondrial and Y-chromosome phylogenies. Most Y-chromosome haplogroup diversity in Africa, however, is present within macrohaplogroup E that seem to have appeared 21 000–32 000 YBP somewhere between the Red Sea and Lake Chad. The combined analysis of 17 bi-allelic markers in 1214 Y chromosomes together with cultural background of 49 populations displayed in various metrics: network, multidimensional scaling, principal component analysis and neighbor-joining plots, indicate a major contribution of East African populations to the foundation of the macrohaplogroup, suggesting a diversification that predates the appearance of some cultural traits and the subsequent expansion that is more associated with the cultural and linguistic diversity witnessed today. The proto-Afro-Asiatic group carrying the E-P2 mutation may have appeared at this point in time and subsequently gave rise to the different major population groups including current speakers of the Afro-Asiatic languages and pastoralist populations.

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The subclades of the network some of which are associated with the practice of pastoralism are most likely to have taken place in the Sahara, among an early population that spoke ancestral language common to both Nilo-Saharan and Afro-Asiatic speakers, although it is yet to be determined whether pastoralism was an original culture to Nilo-Saharan speakers, a cultural acquisition or vice versa; and an interesting notion to entertain in the light of the proposition that pastoralism may be quite an antiquated event in human history.17 Pushing the dates of the event associated with the origin and spread of pastoralism to a proposed 12 000–22 000 YBP, as suggested by the network dating, will solve the matter spontaneously as the language differences would not have appeared by then and an original pastoralist ancestral group with a common culture and language50 is a plausible scenario to entertain. Such dates will accommodate both the Semitic/pastoralism-associated expansion and the introduction of Bos taurus to Europe from North East Africa or Middle East.55 The network result put North African populations like the Saharawi, Morocco Berbers and Arabs in a separate cluster. Given the proposed origin of Maghreb ancestors56, 57, 58, 59 in North Africa, our network dating suggested a divergence of North Western African populations from Eastern African as early as 32 000 YBP, which is close to the estimated dates to the origin of E-P2 macrohaplogroup.30, 60 It can be further inferred that the high frequency of E-M81 in North Africa and its association to the Berber-speaking populations25, 30, 32, 60, 61 may have occurred after the splitting of that early group, leading to local differentiation and flow of some markers as far as Southern Europe.30, 60, 62

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