Evidence for MHC-correlated perfume preferences in humans

Fragrances have been used since at least 5000 years ago and all traditional scents are found in modern perfumes. Although perfumes are obviously invol ved in sexual communication, the significance of great individual differenc es in preference for fragrances is an evolutionary puzzle. The major histoc ompatibility complex (MHC) is a highly polymorphic and conserved set of gen es that plays an important role in immune function in vertebrates. Both mic e and humans have been shown to prefer die body odor of potential partners that have a dissimilar MHC genotype, which would result in heterozygous off spring. We tested whether individual preferences for perfume ingredients co rrelate with a person's MHC genotype. The human MHC is called HLA (human le ukocyte antigen). A total of 137 male and female students who had been type d for their MHC (HLA-A, -B, -DR) scored 36 scents in a first test for use o n self ("Would your like to smell like that yourself?") and a subset of 18 scents 2 years later either for use on self or for a potential partner ("Wo uld you like your partner to smell like that?"). An overall analysis showed a significant correlation between the MHC and the scorings of the scents " for self" in both tests. In a detailed analysis we found a significant inte raction of the two most common HLAs with the rating of the 36 scents in the first study as well as with the 18 scents in the second study when evaluat ed for self. This result suggests that persons who share, for example, HLA- A2, have a similar preference for any of the perfume ingredients. The signi ficant repeatability of these preferences in the two tests showed that the volunteers that had either HLA-A1 or HLA-A2 were significantly consistent i n their preferences for the perfume ingredients offered. Hardly any signifi cant correlation between MHC genotype and ratings of the scents "for partne r" were found. This agrees with the hypothesis that perfumes are selected " for self" to amplify in some wall body odors that reveal a person's immunog enetics.