Previous genetic studies have suggested a history of sub-Saharan African gene flow into some West Eurasian populations after the initial dispersal out of Africa that occurred at least 45,000 years ago. However, there has been no accurate characterization of the proportion of mixture, or of its date. We analyze genome-wide polymorphism data from about 40 West Eurasian groups to show that almost all Southern Europeans have inherited 1%–3% African ancestry with an average mixture date of around 55 generations ago, consistent with North African gene flow at the end of the Roman Empire and subsequent Arab migrations. Levantine groups harbor 4%–15% African ancestry with an average mixture date of about 32 generations ago, consistent with close political, economic, and cultural links with Egypt in the late middle ages. We also detect 3%–5% sub-Saharan African ancestry in all eight of the diverse Jewish populations that we analyzed. For the Jewish admixture, we obtain an average estimated date of about 72 generations. This may reflect descent of these groups from a common ancestral population that already had some African ancestry prior to the Jewish Diasporas.
Posts: 695 | From: وكان المصريون القدماء القوقازين | Registered: Jan 2011
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quote:Originally posted by Perahu: Previous genetic studies have suggested a history of sub-Saharan African gene flow into some West Eurasian populations after the initial dispersal out of Africa that occurred at least 45,000 years ago.
Indeed and the evidence just keeps piling. Good post and full PDF in link. Gonna read it now, see if theres anything new.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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posted
^^^^^ I was wondering the same thing...
Posts: 8805 | From: The fear of his majesty had entered their hearts, they were powerless | Registered: Nov 2007
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A potential issue that could in theory influence our findings is that the exact population contributing to African ancestry in West Eurasians is unknown. To gain insight into the African source populations, we carried out PCA analyses, which suggested that the African ancestry in West Eurasians is at least as closely related to East Africans (e.g. Hapmap3 Luhya (LWK)) as to West Africans (e.g. Nigerian Yoruba (YRI)) (the same analyses show that there is no evidence of relatedness to Chadic populations like Bulala) (Text S5 and Figure S12). We also used the 4 Population Test to assess whether the tree ((LWK, YRI),(West Eurasian, CEU)) is consistent with the data, and found no evidence for a violation, which is consistent with a mixture of either West African or East African ancestors or both contributing to the African ancestry in West Eurasians (Table S14; Figure S13). Historically, a mixture of West and East African ancestry is plausible, since African gene flow into West Eurasia is documented from both West Africa during Roman times [34] and from East Africa during migrations from Egypt [7]. It is important to point out, however, that the difficulty of pinpointing the exact African source population is not expected to bias our inferences about the total proportion and date of mixture. The f4 Ancestry Estimation method is unbiased even when we use a poor surrogates for the true ancestral African population (as long as the phylogeny is correct), as we confirmed by repeating analyses replacing YRI with LWK, and obtaining similar results (Table S15). Our ROLLOFF admixture date estimates are also similar whether we use LWK or YRI to represent ancestral African population (Table S15), as predicted by the theory.
In summary, we have documented a contribution of sub-Saharan African genetic material to many West Eurasian populations in the last few thousand years. A priority for future work should be to identify the source populations for this admixture.
Posts: 695 | From: وكان المصريون القدماء القوقازين | Registered: Jan 2011
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Even though they restrictively and arbitrarily use Nigeria as a reference population for all of "sub-Saharan Africa",and therefore, Africa, it is striking that we still see numbers approaching (and some within) double digits in the southern Levant.
Also interesting from the above quote:
A potential issue that could in theory influence our findings is that the exact population contributing to African ancestry in West Eurasians is unknown. To gain insight into the African source populations, we carried out PCA analyses, which suggested that the African ancestry in West Eurasians is at least as closely related to East Africans (e.g. Hapmap3 Luhya (LWK)) as to West Africans (e.g. Nigerian Yoruba (YRI)) (the same analyses show that there is no evidence of relatedness to Chadic populations like Bulala) (Text S5 and Figure S12). We also used the 4 Population Test to assess whether the tree ((LWK, YRI),(West Eurasian, CEU)) is consistent with the data, and found no evidence for a violation, which is consistent with a mixture of either West African or East African ancestors or both contributing to the African ancestry in West Eurasians (Table S14; Figure S13). Historically, a mixture of West and East African ancestry is plausible, since African gene flow into West Eurasia is documented from both West Africa during Roman times [34] and from East Africa during migrations from Egypt [7].Posts: 4021 | From: Bay Area, CA | Registered: Mar 2007
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^ Yes. I couldn't help but notice the bias slant in heavily associating West Africa with 'Sub-Sahara' when last I checked East Africa is in 'Sub-Sahara' as well and we know that the Sahara itself has never been a barrier let alone always existed in the first place to divide Africa into North and 'Sub-Sahara'!
This is why when West African lineages are combined with East African ones, overall Europeans are one-third African ancestry. Posts: 26307 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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quote:Originally posted by Perahu: To gain insight into the African source populations, we carried out PCA analyses, which suggested that [b]the African ancestry in West Eurasians is at least as closely related to East Africans (e.g. Hapmap3 Luhya (LWK)) as to West Africans (e.g. Nigerian Yoruba (YRI))
Uh, the Luhya are Bantu-speakers and therefore likely have significant West African ancestry. They'd be better off using non-Bantu East Africans.
Posts: 7093 | From: Fallbrook, CA | Registered: Mar 2004
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