Abstract
Extremely high variability in genes of the MHC in vertebrates is assumed to be a consequence of frequency-dependent parasite-driven selection and mate preferences based on promotion of offspring heterozygosity at MHC, or inbreeding avoidance. Here we critically review studies on MHC-associated mate choice in humans.
These are based on: (1) odor preferences, (2) facial preferences and (3) actual mate choice surveys. Most odor-based studies demonstrate disassortative preferences.
In contrast, facial attractiveness research indicates a preference for MHC-similar individuals. Results concerning MHC in actual couples show a bias towards similarity in one study, dissimilarity in two studies and random distribution in several other studies.
This mixed pattern may reflect context-dependent and/or life history sensitive preference expression, in addition to higher level effects arising out of population differences in genetic heterogeneity or cultural and ethnic restrictions on random mating patterns.