African genetic structure

Someone mentioned this story in the comments. Dienekes and Daniel MacArthur have already summarized the paper [1]. Nothing terribly surprising.

One thing to keep in mind: a relatively small number of markers (by recent standards) were typed for this paper.
The combined dataset contains a total of 1,327 genotyped markers (consisting of 848 microsatellites, 476 indels and 3 SNPs) and 3,945 DNA samples. The overall overlap of markers genotyped in the combined dataset is 80% (not all markers were genotyped in all populations) [supplementary material]
Though this should be enough to get the broad picture right, more markers would be nice. As Tishkoff acknowledges in this podcast interview (mp3), the use of "SNP panels [with] a million markers" in future studies should offer knowledge of more subtle variation.

[1] Sarah A. Tishkoff et al. The Genetic Structure and History of Africans and African Americans. Science doi:10.1126/science.1172257


Public Enemy No. 0 said...

Not to be dense, but does this information tend to support Steve Sailer's contention that sub-Saharan Africans are only more diverse than everyone else combined when junk DNA is taken into account? I.e., that if junk DNA are excluded this is no longer true?

n/a said...

"Junk DNA" is something of a misnomer, but it's true that much genetic variation is ostensibly neutral and when you hear some idiot claim there is more genetic variation in an African village than in the rest of the world combined they damn sure aren't talking about functional variants affecting skin, eye, or hair color. They can't be talking about functional variants affecting cognition, either, since few of those are known (likewise for many other phenotypes).