Since incomplete lineage sorting is a random process, I would not expect to see any modern human population significantly more similar to Neandertals than any other modern human population. Modern human populations diverged well after the Neandertal divergence, so whatever genes were still very similar to Neandertals should have been evenly divided. Even more interesting is the geography: the ancestors of the modern humans with Neandertal-like genes come from the same geographic region as the Neandertals. If incomplete lineage sorting is to blame for Neandertal-like genes in modern humans, that geographic pattern would just be a weird coincidence. That's not to say that one couldn't make a case for incomplete lineage sorting, but we would need some new evidence to really seal the deal (such as new samples of Eurasians that don't have Neandertal-like genes or Africans that do).He is right. If modern humans and Neandertals diverged as much as 250 ky BP as many people think, then drift would ensure that the two genomes would be more highly divergent than they appear to be. He is also correct about the geographical coincidence. As I wrote yesterday, the interbreeding conclusion would tend to be supported by the appearance of Neandertal-reminiscent traits in the earliest moderns from the area.
The authors argue that linkage dis-equilibrium, which is when you have allele combinations that are present in two related populations in higher percentages than can be accounted for by chance, supports the recent interbreeding model, a conclusion that Wood agrees with (although how a young-earth creationist can agree with that kind of model, I will never know).