Multiple Instances of Ancient Balancing Selection Shared Between Humans and Chimpanzees
Shared ancestral polymorphisms between species tend to be relatively rare, and studies of trans-species polymorphisms have focused on just a few regions known for balancing selection. Leffler et al. (p. 1578, published online 14 February) performed genome-wide scans among humans and great apes and found shared polymorphisms between chimps and humans. Many of the identified variants seem to be associated with genes involved in pathogen response or defense, suggesting that this widespread balancing selection may reflect the ongoing arms race between pathogens and hosts.