those linked to lactose tolerance or pathogen response90. On the other hand, CLR incorporates information about the spatial pattern of genomic variability (the site frequency spectrum91) and corrects explicitly for evidence of BGS, thus being able to detect signals from 60,000 to 240,000 years ago28. The B statistic uses phylogenetic information from other primates (chimpanzee, gorilla, orangutan and rhesus macaque) to infer the reduction in allelic diversity that exists in humans as a consequence of purifying selection on linked sites over evolutionary time frames92. As the effects of background selection on large genomic regions can mimic those of positive selection46, it is possible that the B statistic might amalgamate both, although the rather large diversity reduction that it infers for the human genome as a whole suggests that any bias due to positive selection is likely to be minor93. Finally, XP-EEH is a haplotype-based statistic that compares two population samples, and its power is thus increased for alleles that have suffered differential selective pressures since those populations diverged90. Although methodologically different, LA has a similar rationale by comparing human and Neanderthal genomes89, to infer the probability of each human haplotype having been the result of an admixture event with Neanderthals.
