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http://www.nature.com/srep/2014/140813/srep06055/full/srep06055.html#ref-link-42
An interesting part of this genome-wide study is that it does not support the suggestion of Botigué et al. (2013) based on imprecise things like IBDs that there has been considerable gene-flow from Africa into southern Europe, particularly SW Europe (Portugal & Spain). The study did not find any significant African (either Northern or sub-Saharan) input in Spaniards:
The Spanish had no significant North African (labelled "Berber" in the study) or sub-Saharan African (the study divided sub-Saharan African into "Lowland East Cushitic", "Niger-Congo", "Nilo-Saharan", "Omotic" and "Pygmy") and the referred to Supplementary Table 1 simply considers it as zero. Northern Italians and Tuscans also had no significant African (either North African or sub-Saharan) and are also labelled as having zero in the table. The only European population sampled in the study that had some North African input were the Sardinians (6.1% "Berber") No European population sampled in the study was found to have any significant sub-Saharan African ancestry.
Pretty different, however, was the study's results regarding Middle Eastern (divided into two: "Arabian" and "Levantine-Caucasian") gene-flow into Europe. Here the study did confirm the suggestion of Botigué et al., as it found more significant amounts of geneflow from this area into Europe:
The amount of Middle Eastern ancestry was higher in Romanians (5.9% "Arabian", 21.2% "Levantine-Caucasian"), then in North Italians & Tuscans (6.9 to 9% "Arabian", 17.2 to 21.1% "Levantine-Caucasian") and less in Spaniards (0 to 5% "Arabian", 6.8 to 9.6% "Levantine-Caucasian"), thus supporting the suggestion of Botigué et al. of a generally declining East-to-West gradient for this ancestry in Europe.
We investigated ancestry of 3,528 modern humans from 163 samples. We identified 19 ancestral components, with 94.4% of individuals showing mixed ancestry. After using whole genome sequences to correct for ascertainment biases in genome-wide genotype data, we dated the oldest divergence event to 140,000 years ago. We detected an Out-of-Africa migration 100,000–87,000 years ago, leading to peoples of the Americas, east and north Asia, and Oceania, followed by another migration 61,000–44,000 years ago, leading to peoples of the Caucasus, Europe, the Middle East, and south Asia. We dated eight divergence events to 33,000–20,000 years ago, coincident with the Last Glacial Maximum. We refined understanding of the ancestry of several ethno-linguistic groups, including African Americans, Ethiopians, the Kalash, Latin Americans, Mozabites, Pygmies, and Uygurs, as well as the CEU sample. Ubiquity of mixed ancestry emphasizes the importance of accounting for ancestry in history, forensics, and health.
An interesting part of this genome-wide study is that it does not support the suggestion of Botigué et al. (2013) based on imprecise things like IBDs that there has been considerable gene-flow from Africa into southern Europe, particularly SW Europe (Portugal & Spain). The study did not find any significant African (either Northern or sub-Saharan) input in Spaniards:
Additionally, the PUR sample showed a significant amount of Berber ancestry, which likely did not derive from a Spanish parental population as none of the three Spanish samples (Spain_Basque, IBS (Iberian population in Spain), and Spain) showed significant amounts of Berber ancestry (Supplementary Fig. 4 and Supplementary Table 1)32.
The Spanish had no significant North African (labelled "Berber" in the study) or sub-Saharan African (the study divided sub-Saharan African into "Lowland East Cushitic", "Niger-Congo", "Nilo-Saharan", "Omotic" and "Pygmy") and the referred to Supplementary Table 1 simply considers it as zero. Northern Italians and Tuscans also had no significant African (either North African or sub-Saharan) and are also labelled as having zero in the table. The only European population sampled in the study that had some North African input were the Sardinians (6.1% "Berber") No European population sampled in the study was found to have any significant sub-Saharan African ancestry.
Pretty different, however, was the study's results regarding Middle Eastern (divided into two: "Arabian" and "Levantine-Caucasian") gene-flow into Europe. Here the study did confirm the suggestion of Botigué et al., as it found more significant amounts of geneflow from this area into Europe:
Note 33 refers to Botigué et al. and its IBD-based claims specifically.The Spanish and Italian samples showed southern and northern European ancestry with varying amounts of Levantine-Caucasian, Arabian, and Berber ancestry (Supplementary Fig. 5 and Supplementary Table 1). In contrast, the Basque samples showed only southern and northern European ancestry (Supplementary Fig. 5 and Supplementary Table 1), consistent with genetic isolation. Also, we detected more Arabian than Berber ancestry in Spain and Italy33. The oft-used CEU sample showed northern European, southern European, and Levantine-Caucasian ancestry, similar to the GBR (British in England and Scotland) and French samples (Supplementary Fig. 5 and Supplementary Table 1).
The amount of Middle Eastern ancestry was higher in Romanians (5.9% "Arabian", 21.2% "Levantine-Caucasian"), then in North Italians & Tuscans (6.9 to 9% "Arabian", 17.2 to 21.1% "Levantine-Caucasian") and less in Spaniards (0 to 5% "Arabian", 6.8 to 9.6% "Levantine-Caucasian"), thus supporting the suggestion of Botigué et al. of a generally declining East-to-West gradient for this ancestry in Europe.