Reprising genes & geography

By Razib Khan | April 16, 2012 11:25 pm

Comparing Spatial Maps of Human Population-Genetic Variation Using Procrustes Analysis:

Recent applications of principal components analysis (PCA) and multidimensional scaling (MDS) in human population genetics have found that “statistical maps” based on the genotypes in population-genetic samples often resemble geographic maps of the underlying sampling locations. To provide formal tests of these qualitative observations, we describe a Procrustes analysis approach for quantitatively assessing the similarity of population-genetic and geographic maps. We confirm in two scenarios, one using single-nucleotide polymorphism (SNP) data from Europe and one using SNP data worldwide, that a measurably high level of concordance exists between statistical maps of population-genetic variation and geographic maps of sampling locations….

There is concordance. But look at the figure below. On the left are populations where they were sampled, and the right shows the populations displayed in a manner to reflect genetic distances.

I don’t want to make too much of this. The HGDP populations tend to be sampled from particularly distinctive groups consciously. But it does look like there is a stronger genetic clustering effect than one can predict from geography alone. That warrants investigation. I will leave the rest for comment.

  • Justin Giancola

    I’m seeing evidence of substructure and superstructure just as one might predict! – no?

  • Onur

    More like we see evidence of human races, I’d say, as humans are genetically too clustered for their geographical position. They form tight genetic clusters that have long distances to each other, with some scattered hybrid groups occupying some parts of the largely empty zones between the clusters.


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About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at


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