Extent of Black Admixture in the Mediterranean

January 20, 2010

González-Pérez et al. (2010) have analyzed populations from the northern and southern shores of the Mediterranean, with Central Europeans and West Africans as external references. They estimate Sub-Saharan African admixture using two methods that yield vastly disparate results. In the Discussion section, they admit that the inflated "Alu/STR estimate might be artefactual" and favor the estimate based on the Alu loci set alone because it's consistent with previous mtDNA, Y-chromosome and 500,000-SNP structure data.

According to the more accurate latter method, Sub-Saharan African admixture is ~13% in North Africa and "imperceptible" (~0.01%) in Southern Europe:

Here are the locations of the sampled populations and an MDS plot showing their genetic distances, again based on the preferred method:

Northern Mediterraneans are almost equidistant from both Central Europe (0.0526 ± 0.015) and Southern Mediterraneans (0.049 ± 0.025), showing distances very close to those between the latter two population groups (0.042 ± 0.013). MDS representation of the genetic distances (see Fig. 2) based on autosomal Alu data stresses the main differentiation of sub-Saharans, the clustering of Mediterraneans in two different groups corresponding to northern and southern populations, and the distant position of the Egyptian Siwa and the Spanish Pas Valley samples from their corresponding population clusters.

González-Pérez et al. "Population relationships in the Mediterranean revealed by autosomal genetic data (Alu and Alu/STR compound systems)". Am J Phys Anthropol, 2010.