Genetic and phenotypic cues associated with facial attractiveness and health

Abstract

Facial attractiveness plays a crucial role in human mate choice, with individuals from both sexes using facial attractiveness cues to some degree when choosing a partner. Although some of the general facial attractiveness preferences have been studied in cross-cultural populations, most of the research focused specifically on Western populations. Most previous studies also approached facial attractiveness solely from a psychological point of view. One notable exception was a recent study by Roberts et al. (2005) in which the authors linked the Human Leococyte Antigen (HLA) system to cues for health and facial attractiveness in males. This study provides fascinating evidence that genes involved in the immune response also signal attractiveness and health. But is this true cross-culturally and across genders? Roberts et al. (2005) used a British population, who compared to other populations worldwide, have relatively few pathogens that routinely challenge their immune response. The first objective of our study was to test the role of the HLA system in an African female population with a high pathogen load. We found that common HLA alleles, that seemingly provide resistance against common pathogens, play a more important role in health measures than heterozygosity per se. However, our results showed these individuals were not necessarily rated more attractive. So which facial cues do individuals from our study population find attractive in the opposite sex? According to this study individuals from both sexes prefer neotenous features in the opposite sex. Interestingly, we found no preference for facial symmetry and only a slight preference for femininity in females. Our findings support the hypothesis by Boothroyd et al. (2005) that preference for femininity is a by-product of preference for neotenous cues. To test if ethnic preference could not play a confounding role in facial attractiveness ratings of the ethnically mixed South African population, we tested ethnic recognition in two abundant South African ethnic groups. Our results showed that individuals from both sexes could not reliably assign ethnicity to facial images of the two groups. Ethnic preference could therefore not play a role in our study. But mate choice does not only depend on cues displayed by the person being observed. Conditional dependent factors, inherent to the observer, influence how choosy they are of potential partners and therefore how attractive they rate members of the opposite sex. We tested the role of three condition dependent factors, age self-perceived attractiveness and relationship status in both sexes. We observed no significant difference in choosiness between males and females. Male choice therefore plays a more important role in human mate choice than previously expected. Furthermore, our study showed that condition dependent factors affect choosiness differently in males and females. Females are generally more sensitive to condition dependent factors, especially self-perceived attractiveness, while males showed no correlation between any of the condition-dependent factors and choosiness. Since HIV is so prevalent in the South African population, we also tested the role of self esteem in predicting sexual risky behaviour. Our results showed that high self-esteem males were more likely to be sexually active after the age of 18, but that males with low self-esteem were more likely to start sexual activity prematurely. We observed no significant correlation for females. These results indicate that HIV prevention campaigns should focus more on behavioural outcomes other than abstinence, instead of challenging the cultural norms, as indicated by the behavior of high self-esteem individuals. In conclusion, this dissertation is based on the first comprehensive study of genetic and conditional cues associated with facial attractiveness and health in an African population. This African population, with its high pathogen load, high diversity and novel cultural background provided many novel findings, which would hopefully contribute to a more universal view of human mate choice.