Deep haplotype divergence and long-range linkage disequilibrium at Xp21.1 provide evidence that humans descend from a structured ancestral population. Please note that the authors moot the possibility of natural selection maintaining this allele, though they seem to favor introgression from a population with a separate lineal history followed by interbreeding/absorption into the "modern"1 population. I recommend John Hawk's critique of the logic of some of these studies.
Via Dienekes.
Related: The Middle Model, Paradigms Lost and The "fertility inversion".
1 - If "fitness is a bugger" I am beginning to really consider that "species is a bugger" too.
