Yann points me to a new paper, Complex signatures of selection for the melanogenic loci TYR, TYRP1 and DCT in humans:
Diversity patterns clearly evidence adaptive selection in pigmentation genes in Africans and Asians. In Europeans, the evidence is more complex, and both directional and balancing selection may be involved in light skin. As a result, different non-African populations may have acquired light skin by alternative ways, and so light skin, and perhaps dark skin too, may be the result of convergent evolution.
As noted above the paper, which is provisional and subject to later reedits, does some analysis of gene expression and doesn't find clear differences between fair and dark individuals that one would expect. Then it goes off on a tangent interpreting various statistical tests of natural selection, especially Tajima's D, on a few loci in various populations to offer up a very complex picture of varieties of ...
