The mating behaviours of humans are influenced by differences in human leukocyte antigen (HLA), a molecule of the immune system that is associated with body odour preference.
Many men and women are sexually attracted to their partners’ body odour. This attraction between people is partly mediated by their immune system and perceived through their sense of smell. Major histocompatibility complexes (MHCs) are immune system molecules on the surface of cells that have the ability to detect and discriminate pathogens. Mice and fish prefer mates who have MHCs that are genetically dissimilar to their own, which is advantageous on an evolutionary level as it leads to offspring with high MHC variety and enhanced resilience to pathogens. In humans, MHC is called human leukocyte antigen (HLA), and it is not clear as to whether human mating behaviour is affected by HLA immunologic compatibility. A recent study examined whether similarities in HLA influence body odour attractiveness, general partnership satisfaction, sexual satisfaction, and the desire to have children with a partner.
Over the course of nine months, 256 heterosexual couples between 18 and 60 years old participated in the study. The duration of partnership ranged between one month to 32 years, with a mean duration of 4 years. 90% of couples had no children. Participants provided their DNA via mouth swabs for HLA analysis and independently completed a questionnaire based on their health and partnership that rated their sexual satisfaction, partnership sexuality, attractiveness of their partner’s body odour, and whether they wanted to have (more) children with their partner.
The results show that HLA dissimilarity is significantly correlated with higher partnership satisfaction and sexual satisfaction. Men and women who reported high partnership satisfaction were influenced by the dissimilarity of a specific sub-class of HLA, HLA Class I (of I and II). Women were more likely to want children with their partners who had different HLA Class I molecules, while no effect was observed in men. HLA type dissimilarity was also significantly associated with higher body odour attractiveness for both men and women. Relationship duration and exclusion of partners who already had children did not impact the results.
This study demonstrates that male and female participants were satisfied overall with their relationship if their partner had a dissimilar HLA type. It supports work that mate choice of mammals is influenced by immunologic compatibility and that humans can discriminate HLA-related odours. Therefore, if a male is unsatisfied with their relationship, it could be due partially to HLA similarity or an unsatisfied female partner, as the current study shows that women are more influenced by HLA type than men.
Written By: Fiona Wong, PhD