A reader alerted me to this recent article on the subject of how human genetic variation is best described. I'll comment on it later on, but it is definitely worth reading, as it poses a sophisticated challenge to the concept of race - unlike many other heavily politicized writings on the subject.
Genome Research 14:1679-1685, 2004
Evidence for Gradients of Human Genetic Diversity Within and Among Continents
David Serre et al.
Genetic variation in humans is sometimes described as being discontinuous among continents or among groups of individuals, and by some this has been interpreted as genetic support for "races." A recent study in which >350 microsatellites were studied in a global sample of humans showed that they could be grouped according to their continental origin, and this was widely interpreted as evidence for a discrete distribution of human genetic diversity. Here, we investigate how study design can influence such conclusions. Our results show that when individuals are sampled homogeneously from around the globe, the pattern seen is one of gradients of allele frequencies that extend over the entire world, rather than discrete clusters. Therefore, there is no reason to assume that major genetic discontinuities exist between different continents or "races."