The gray mouse lemur is a species in which females come into estrus and mate with several males on one night each year. Females accept any and all partners, but a genetic analysis of offspring produced by female gray mouse lemurs indicates that mothers and actual fathers differed with respect to their MHC genes to a greater degree than mothers and males selected at random from the population. Use these results to evaluate the various hypotheses on the indirect genetic benefits of polyandry. What do they suggest about the mechanism that enables a sexually promiscuous female mammal to exercise mate choice?