August 25, 2010

Novel component in the genetic structure of sub-Saharan Africans

Post will be updated after I read the paper. (Last Update Aug 29)

UPDATE I (Aug 29):

Here is the PCA plot with the full marker set:

It is the familiar V shape, with Caucasoids at the bottom, and Mongoloids/Negroids at the left/right tips. Notice the variable position of Middle Eastern Arabs (brown) which corresponds to their variable African affiliation, and the heterogeneous group of populations between Caucasoids and Mongoloids, which includes mainly South-Central Asians but also a couple of (yellow) clusters of Papuan-Melanesians.

It is useful to zoom in on the African portion of the plot: notice the circles and diamonds for African Americans and Maasai that are tilted toward Caucasoids, while the crosses and squares for Pygmies are further removed near the top right.

European Journal of Human Genetics doi: 10.1038/ejhg.2010.141

A genomic analysis identifies a novel component in the genetic structure of sub-Saharan African populations

Martin Sikora et al.


Studies of large sets of single nucleotide polymorphism (SNP) data have proven to be a powerful tool in the analysis of the genetic structure of human populations. In this work, we analyze genotyping data for 2841 SNPs in 12 sub-Saharan African populations, including a previously unsampled region of southeastern Africa (Mozambique). We show that robust results in a world-wide perspective can be obtained when analyzing only 1000 SNPs. Our main results both confirm the results of previous studies, and show new and interesting features in sub-Saharan African genetic complexity. There is a strong differentiation of Nilo-Saharans, much beyond what would be expected by geography. Hunter-gatherer populations (Khoisan and Pygmies) show a clear distinctiveness with very intrinsic Pygmy (and not only Khoisan) genetic features. Populations of the West Africa present an unexpected similarity among them, possibly the result of a population expansion. Finally, we find a strong differentiation of the southeastern Bantu population from Mozambique, which suggests an assimilation of a pre-Bantu substrate by Bantu speakers in the region.


1 comment:

Ortu Kan said...

As I read the Sikora paper, I recalled a 16th-century traveler who may well have encountered click speakers in the mountains of Mozambique. More on that here (disclaimer: my own blog).