Isabel M. Scott

Do men’s faces really signal heritable immunocompetence?

In the literature on human mate choice, masculine facial morphology is often proposed to be an intersexual signal of heritable immunocompetence, and hence an important component of men’s attractiveness. This hypothesis has received considerable research attention, and is increasingly treated as plausible and well supported. In this article, we propose that the strength of the evidence for the immunocompetence hypothesis is somewhat overstated, and that a number of difficulties have been under-acknowledged. Such difficulties include (1) the tentative nature of the evidence regarding masculinity and disease in humans, (2) the complex and uncertain picture emerging from the animal literature on sexual ornaments and immunity, (3) the absence of consistent, cross-cultural support for the predictions of the immunocompetence hypothesis regarding preferences for masculinized stimuli, and (4) evidence that facial masculinity contributes very little, if anything, to overall attractiveness in real men. Furthermore, alternative explanations for patterns of preferences, in particular the proposal that masculinity is primarily an intrasexual signal, have been neglected. We suggest that immunocompetence perspectives on masculinity, whilst appealing in many ways, should still be regarded as speculative, and that other perspectives–and other traits–should be the subject of greater attention for researchers studying human mate preferences.

Does Masculinity Matter? The Contribution of Masculine Face Shape to Male Attractiveness in Humans

Background In many animals, exaggerated sex-typical male traits are preferred by females, and may be a signal of both past and current disease resistance. The proposal that the same is true in humans – i.e., that masculine men are immunocompetent and attractive – underpins a large literature on facial masculinity preferences. Recently, theoretical models have suggested that current condition may be a better index of mate value than past immunocompetence. This is particularly likely in populations where pathogenic fluctuation is fast relative to host life history. As life history is slow in humans, there is reason to expect that, among humans, condition-dependent traits might contribute more to attractiveness than relatively stable traits such as masculinity. To date, however, there has been little rigorous assessment of whether, in the presence of variation in other cues, masculinity predicts attractiveness or not. Methodology/Principal Findings The relationship between masculinity and attractiveness was assessed in two samples of male faces. Most previous research has assessed masculinity either with subjective ratings or with simple anatomical measures. Here, we used geometric morphometric techniques to assess facial masculinity, generating a morphological masculinity measure based on a discriminant function that correctly classified >96% faces as male or female. When assessed using this measure, there was no relationship between morphological masculinity and rated attractiveness. In contrast, skin colour – a fluctuating, condition-dependent cue – was a significant predictor of attractiveness. Conclusions/Significance These findings suggest that facial morphological masculinity may contribute less to mens attractiveness than previously assumed. Our results are consistent with the hypothesis that current condition is more relevant to male mate value than past disease resistance, and hence that temporally fluctuating traits (such as colour) contribute more to male attractiveness than stable cues of sexual dimorphism.

National income inequality predicts women's preferences for masculinized faces better than health does

In their paper ‘The health of a nation predicts their mate preferences’, DeBruine et al. [[1][1]] find that womens preferences for facial masculinity from a large, cross-cultural sample of individuals from developed countries is negatively correlated with a composite National Health Index (NHI

Human preferences for sexually dimorphic faces may be evolutionarily novel

Significance It is a popular assumption that certain perceptions—for example, that highly feminine women are attractive, or that masculine men are aggressive—reflect evolutionary processes operating within ancestral human populations. However, observations of these perceptions have mostly come from modern, urban populations. This study presents data on cross-cultural perceptions of facial masculinity and femininity. In contrast to expectations, we find that in less developed environments, typical “Western” perceptions are attenuated or even reversed, suggesting that Western perceptions may be relatively novel. We speculate that novel environments, which expose individuals to large numbers of unfamiliar faces, may provide novel opportunities—and motives—to discern subtle relationships between facial appearance and other traits. A large literature proposes that preferences for exaggerated sex typicality in human faces (masculinity/femininity) reflect a long evolutionary history of sexual and social selection. This proposal implies that dimorphism was important to judgments of attractiveness and personality in ancestral environments. It is difficult to evaluate, however, because most available data come from large-scale, industrialized, urban populations. Here, we report the results for 12 populations with very diverse levels of economic development. Surprisingly, preferences for exaggerated sex-specific traits are only found in the novel, highly developed environments. Similarly, perceptions that masculine males look aggressive increase strongly with development and, specifically, urbanization. These data challenge the hypothesis that facial dimorphism was an important ancestral signal of heritable mate value. One possibility is that highly developed environments provide novel opportunities to discern relationships between facial traits and behavior by exposing individuals to large numbers of unfamiliar faces, revealing patterns too subtle to detect with smaller samples.

Male facial masculinity as a cue to health outcomes.

Evolutionary theories of human attraction draw heavily upon nonhuman literature, and currently the Immunocompetence Handicap Hypothesis dominates research into female attraction to male facial masculinity. Although some studies have shown links between masculinity and some measures of health, other data have failed to support the Immunocompetence Hypothesis as applied to human face preferences. Here we summarize that literature and present new data regarding links between masculinity and multiple measures of health condition in human males. Undergraduate males were photographed and their faces were assessed for sexual dimorphism using multiple methods and rated for apparent healthiness and attractiveness. Participants also reported recent health experiences both prior to being photographed and then again 10 weeks later. Although both attractiveness and rated health were associated with better actual health in the past and future (mainly indexed by lower antibiotic use), results were mixed for masculinity. With respect to respiratory illnesses, facial masculinity (assessed using morphometric techniques) was associated with better past health but with worse future health. Possible reasons for the complex and inconsistent findings are discussed and some potentially fruitful avenues of future research are outlined.

The validity of composite photographs for assessing masculinity preferences.

Among non-human animals, exaggerated male traits may signal immunocompetence and are often attractive to females. This finding has not been reliably replicated in human populations, however, where preferences for feminised male faces are often observed in experiments. Some authors have suggested that certain experimental approaches, and in particular the use of ‘composite’, or averaged, photographs, may lack ecological validity and elicit misleading responses. This may account for reports of preferences for femininity. To date, however, experiments have varied on numerous, often confounded, methodological dimensions, making the contribution of different factors difficult to assess. To address this, we conducted an experiment to examine the influence of stimulus type on participant responses. Masculinity preferences were measured using both composite photographs and the photographs from which they were composed, while all other methodological variables were held constant. In contrast to predictions by previous authors, composites elicited significantly stronger overall preferences for masculinity, especially when textural information was reduced during the averaging process. The existence of preferences for feminised male faces is unlikely to be explained by the use of composite photographs alone.

An evolutionary perspective on male preferences for female body shape

Cross-culturally, humans make systematic use of physical attractiveness to discriminate among members of the opposite sex, and physical cues to youth, health, and fertility may be particularly important to men (Buss, 1989). Nevertheless, there is controversy over whether attraction preferences are adaptive, particularly in novel environments, and whether they are universal or flexible depending on cultural circumstances (Singh & Luis, 1995). To date, a good deal of research into somatic (i.e., body) attractiveness has focused on two particular characteristics: waist-to-hip ratio (WHR) and the body mass index (BMI). WHR is calculated as the circumference of the waist divided by circumference of the hips, and provides an index of a woman’s ‘curvaceousness.’ BMI is calculated as an individual’s weight (kilogrammes) divided by height (metres) squared, and provides an estimate of body fatness.

Indirect questioning method reveals hidden support for female genital cutting in South Central Ethiopia

Female genital cutting (FGC) has major implications for women’s physical, sexual and psychological health, and eliminating the practice is a key target for public health policy-makers. To date one of the main barriers to achieving this has been an inability to infer privately-held views on FGC within communities where it is prevalent. As a sensitive (and often illegal) topic, people are anticipated to hide their true support for the practice when questioned directly. Here we use an indirect questioning method (unmatched count technique) to identify hidden support for FGC in a rural South Central Ethiopian community where the practice is common, but thought to be in decline. Employing a socio-demographic household survey of 1620 Arsi Oromo adults, which incorporated both direct and indirect direct response (unmatched count) techniques we compare directly-stated versus privately-held views in support of FGC, and individual variation in responses by age, gender and education and target female (daughters versus daughters-in-law). Both genders express low support for FGC when questioned directly, while indirect methods reveal substantially higher acceptance (of cutting both daughters and daughters-in-law). Educated adults (those who have attended school) are privately more supportive of the practice than they are prepared to admit openly to an interviewer, indicating that education may heighten secrecy rather than decrease support for FGC. Older individuals hold the strongest views in favour of FGC (particularly educated older males), but they are also more inclined to conceal their support for FGC when questioned directly. As these elders represent the most influential members of society, their hidden support for FGC may constitute a pivotal barrier to eliminating the practice in this community. Our results demonstrate the great potential for indirect questioning methods to advance knowledge and inform policy on culturally-sensitive topics like FGC; providing more reliable data and improving understanding of the “true” drivers of FGC.