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Chad Genetic Diversity : Multiple Eurasian Migrations 2016
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[QUOTE]Originally posted by the lioness,: [QB] [QUOTE]Originally posted by the lioness,: [QB] [QUOTE]Originally posted by Djehuti: [QB] Again, I ask why it seems the author is trying to associate R1 in Africa with Chadic or Afrasian when it's highest frequency is among Niger-Congo speakers? [/QUOTE] [QUOTE] [QUOTE] Within Africa, the highest frequencies of the R-V88 haplogroup (and its commonest sub-clade, R-V69) were observed in the central Sahel (northern Cameroon, northern Nigeria, Chad, and Niger) (Table 1; Figure 3). Immediately south of this region (southern Cameroon and southern Nigeria), frequencies drastically dropped to 0.0–4.8%. The central Sahel is characterized by a strong linguistic fragmentation with populations speaking languages belonging to three of the four linguistic families of Africa (Afroasiatic, Niger-Congo, and Nilo-Saharan). When the linguistic affiliation of the populations from the central Sahel was also taken into account, a clear-cut divide was observed between those speaking Afroasiatic languages (including the Berber-speaking Tuareg, the Semitic Arab Shuwa, and Chadic-speaking populations from northern Cameroon) and the other populations (Mann–Whitney test P=1.4 × 10−3), with Chadic-speaking populations mostly contributing to this difference. It is worth noting that, if the finding of 20% R-V88 chromosomes among the Hausa (Table 1) is representative, this population, encompassing by far more people than all other Chadic speakers,44 also encompasses the highest absolute number of V88 carriers. In contrast to prior studies on nuclear (mostly autosomal) ins/del and microsatellite markers,45 the Chadic are distinguished from the Nilo-Saharan-speaking populations at the Y chromosome variation level (Table 1; Supplementary Table 3). Repeated assimilations of Nilo-Saharan females over generations may account for these conflicting signals. Among the Niger-Congo-speaking populations, the frequency of the haplogroup R-V88 ranged between 0.0 and 66.7%. Outside central Africa, haplogroup R-V88 was only observed in Afroasiatic-speaking populations from northern Africa, with frequencies ranging from 0.3% in Morocco, to 3.0% in Algeria, and to 11.5% in Egypt, where a particularly high frequency (26.9%) was observed among the Berbers from the Siwa Oasis. Although the presence of the haplogroup R-V88 at non-negligible frequencies in some Niger-Congo-speaking populations from the central Sahel can be accounted for by Chadic admixture favored by geographic contiguity, the presence of this haplogroup both in northern Africa and the central Sahel is especially intriguing given that >1500 km across the Sahara separate the two regions. The expansion time for the haplogroup R-V88 in Africa, under two different population models (see Materials and methods), was found to be 9.2–5.6 ky (95% CI=7.6–10.8 ky and 4.7–6.6 ky, respectively). Diverse hypotheses have been proposed to explain the process by which proto-Chadic speakers arrived to the Lake Chad region. Ehret46 has put forward a model for Afroasiatic languages with a primary division between the Omotic languages of Ethiopia and an Erythraean subgroup. This, in turn, has been subdivided into Cushitic and North Erythraean, the latter including Berber, Semitic, Ancient Egyptian, and Chadic. In his opinion, around 7000 kya proto-Chadic Afroasiatic speakers may have moved west through the Central Sahara and then farther south into the Lake Chad Basin.47 Blench,48 in turn, suggested that speakers of proto-Cushitic–Chadic language migrated east-to-west from the Middle Nile to the Lake Chad, and recent mtDNA data support this view.49 However, in contrast to the mtDNA, a strong connection between Chadic and other Afroasiatic populations from Northern Africa is revealed by the Y chromosome data. This finding would indicate the trans-Saharan47 a more likely scenario than the inter-Saharan hypothesis,48 at least as far as the male component of gene pool is concerned. In this view, it is tempting to speculate that the Y chromosome haplogroup R-V88 represents a preserved genetic record of gene flow along the same axis as the proposed spread of proto-Chadic languages.47 Indeed, geomorphological evidence4 from the paleolakes that existed in the Sahara during the mid-Holocene indicates that these lakes could have covered an area as large as about 10% of the Sahara, providing an important corridor for human migrations across the region.5 In summary, our data indicate a significant male contribution from northern Africa (and ultimately Asia) to the gene pool of the central Sahel. The trans-Saharan population movements resulting in this genetic pattern would seem to mirror the spread of the proto-Chadic languages, and most likely took place during the early mid Holocene, a period when giant paleolakes may have provided a corridor for human migrations across what is now the Sahara desert. Human Y chromosome haplogroup R-V88: a paternal genetic record of early mid Holocene trans-Saharan connections and the spread of Chadic languages Fulvio Cruciani 2010 [/QUOTE]^ see Ish Gebor, this is how to quote properly. The quote is directly related to answer the question rather than on a tangent [/QB][/QUOTE]
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