Eurasian Y chromosome R1b in Africa.

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 et al.

Abstract

Although human Y chromosomes belonging to haplogroup R1b are quite rare in Africa, being found mainly in Asia and Europe, a group of chromosomes within the paragroup R-P25* are found concentrated in the central-western part of the African continent, where they can be detected at frequencies as high as 95%. Phylogenetic evidence and coalescence time estimates suggest that R-P25* chromosomes (or their phylogenetic ancestor) may have been carried to Africa by an Asia-to-Africa back migration in prehistoric times. Here, we describe six new mutations that define the relationships among the African R-P25* Y chromosomes and between these African chromosomes and earlier reported R-P25 Eurasian sub-lineages. The incorporation of these new mutations into a phylogeny of the R1b haplogroup led to the identification of a new clade (R1b1a or R-V88) encompassing all the African R-P25* and about half of the few European/west Asian R-P25* chromosomes. A worldwide phylogeographic analysis of the R1b haplogroup provided strong support to the Asia-to-Africa back-migration hypothesis. The analysis of the distribution of the R-V88 haplogroup in >1800 males from 69 African populations revealed a striking genetic contiguity between the Chadic-speaking peoples from the central Sahel and several other Afroasiatic-speaking groups from North Africa. The R-V88 coalescence time was estimated at 9200–5600 kya, in the early mid Holocene. We suggest that R-V88 is a paternal genetic record of the proposed mid-Holocene migration of proto-Chadic Afroasiatic speakers through the Central Sahara into the Lake Chad Basin, and geomorphological evidence is consistent with this view.

I haven’t had a look at the full text for this yet, but relevant to this is the mt DNA study of Chadic speakers which showed a passage from East Africa (somewhere to the West of the Nile in the Sudan is my guess, it’s the only place the v88 and L3f3 would meet up).

 A date ~8,000 YBP was estimated for the L3f3 sub-haplogroup, which is in good agreement with the supposed migration of Chadic speaking pastoralists and their linguistic differentiation from other Afro-Asiatic groups of East Africa.

Which isn’t inconsistent with the date for V88 proposed at 9,200-5,600 years, and is also a very close match for the arrival of the Neolithic in Africa.

 Just a brief  note on the mt DNA  study: the only Afro-Asiatic speaking group that the Chadic speakers plot closely to is Cushitic, which will probably make Blench happy, as he claims Chadic speakers are a split-off from Cushitic speaking pastoralists. It’s fairly obvious that the male line of Chadic speakers followed a path into Africa via the Sinai, then down the West bank of the Nile and then struck out West to Lake Chad, acquiring wives as they went. The only issue is the exact date. Holocene or Neolithic? Whatever the exact date, this brings the argument for an Asian origin for Afro-Asiatic out again, as (from the DNA here) the odds are 50% that it followed the male line in from Asia. I would like to comment that Chadic has cognates for sheep and goats that look like they share a root with Cushitic and Egyptian, which would at least date proto Chadic to the Neolithic, making the mt DNA date of 8,000 more likely to be close to the actual date for V88 to enter Africa.

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