A few days ago I saw that Dienekes commented on a recent paper published in The American Journal of Human Genetics where the authors used 10 markers, specifically single nucleotide polymorphisms (SNPs), to discern continental level population differentiation. Dienekes has generated a map which shows the extent of clustering. The authors selected specific SNPs that they assumed would be extremely informative, and so obviated the need to extend their sample of assayed loci into hundreds. They express their results with some caution, and highlight that the inferences need to be judged in light of the assumptions and biological realities. Additionally,
the loci in question are informative on the continental level precisely because they seem to be regions subject to powerful positive selection
. This is somewhat of a banal observation in the post-genomic HapMap age, but, for those of you who want to read the full article and don't have institutional access, I found that google's HTML conversion of the PDF is available! Click while it works.