Andrew P. Clark

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.

Self-perceived attractiveness and masculinization predict women's sociosexuality

Abstract Women vary with respect to monogamous/polyandrous inclinations, as indexed by the Sociosexual Orientation Inventory (SOI). Possible sources of SOI variation include variation in perceptions relating to the utility of different mating tactics and variation in ones degree of masculinity/femininity, among other things. In three studies with undergraduate participants SOI, an index of self-perceived attractiveness and two measures of masculinization, namely scores on the Vandenberg Mental Rotation test (V-MRT) and 2D:4D digit ratios, were measured. Self-perceived attractiveness predicted SOI in the first study, but not in the second study. Right 2D:4D did predict SOI in the second study. In the third study, both self-perceived attractiveness and right 2D:4D predicted SOI, and so did V-MRT scores. However, the strongest single predictor of SOI in Study 3 was the reported amount spent on alcohol during the average month.

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.

Turning the other cheek: the viewpoint dependence of facial expression after-effects

How do we visually encode facial expressions? Is this done by viewpoint-dependent mechanisms representing facial expressions as two-dimensional templates or do we build more complex viewpoint independent three-dimensional representations? Recent facial adaptation techniques offer a powerful way to address these questions. Prolonged viewing of a stimulus (adaptation) changes the perception of subsequently viewed stimuli (an after-effect). Adaptation to a particular attribute is believed to target those neural mechanisms encoding that attribute. We gathered images of facial expressions taken simultaneously from five different viewpoints evenly spread from the three-quarter leftward to the three-quarter rightward facing view. We measured the strength of expression after-effects as a function of the difference between adaptation and test viewpoints. Our data show that, although there is a decrease in after-effect over test viewpoint, there remains a substantial after-effect when adapt and test are at differing three-quarter views. We take these results to indicate that neural systems encoding facial expressions contain a mixture of viewpoint-dependent and viewpoint-independent elements. This accords with evidence from single cell recording studies in macaque and is consonant with a view in which viewpoint-independent expression encoding arises from a combination of view-dependent expression-sensitive responses.

Facial width-to-height ratio predicts self-reported dominance and aggression in males and females, but a measure of masculinity does not

Recently, associations between facial structure and aggressive behaviour have been reported. Specifically, the facial width-to-height ratio (fWHR) is thought to link to aggression, although it is unclear whether this association is related to a specific dimension of aggression, or to a more generalized concept of dominance behaviour. Similarly, an association has been proposed between facial masculinity and dominant and aggressive behaviour, but, to date, this has not been formally tested. Because masculinity and fWHR are negatively correlated, it is unlikely that both signal similar behaviours. Here, we thus tested these associations and show that: (i) fWHR is related to both self-reported dominance and aggression; (ii) physical aggression, verbal aggression and anger, but not hostility are associated with fWHR; (iii) there is no evidence for a sex difference in associations between fWHR and aggression; and (iv) the facial masculinity index does not predict dominance or aggression. Taken together, these results indicate that fWHR, but not a measure of facial masculinity, cues dominance and specific types of aggression in both sexes.

Photostimulation induces rapid growth of song-control brain regions in male and female chickadees (Poecile atricapilla)

To examine the effect of photoperiodic condition on song-control nuclei we examined three groups of male and female black-capped chickadees (Poecile atricapilla). Photorefractory birds were held on long days for several months and had fully regressed gonads. Photosensitive birds were held on short days for several months and had small gonads. Photostimulated birds were transferred to long days for 16 days following several months of short days. Following these photoperiod treatments we determined the volume of the song-control nuclei HVc, Area X, and (RA). There were significant sex differences in HVc and Area X, but not in RA. There were also significant photoperiod effects in HVc and Area X. Thus, sex and photoperiod differences in the song system exist in a species in which both sexes produce learned calls year-round.

Attracting Interest: Dynamic Displays of Proceptivity Increase the Attractiveness of Men and Women

Proceptive signals may influence judgments of opposite-sex attractiveness because these signals indicate high mate quality and/or non-threatening behavior but they may also signal high probable rate of return for mating effort. If so, individuals observing these signals may be sensitive to where the signals are directed to; signals directed toward other individuals may not predict what signals would be directed toward the observer. To explore these possibilities I made use of video stimuli composed of mock interviews with actors. Each actor did one proceptive and one unreceptive interview. Each interview was presented as being directed toward participants or toward an opposite sex interviewer. Proceptivity enhanced the attractiveness of opposite-sex actors and an interaction between proceptive state and signal direction was found, with this pattern varying substantially between actors. The possibility that this variation is mediated by the physical attractiveness and sex of the actors will be discussed.

Women's probability of conception is associated with their preference for flirtatious but not masculine facial movement

Women’s preferences for facial structure vary over the menstrual cycle. Little is known, however, as to how preferences for behavior may be influenced by hormonal factors. Here, we demonstrate that social properties of facial motion influence attractiveness judgments in the absence of other cues, and that women’s preferences for these displays vary over the menstrual cycle, as has been demonstrated for structural traits of men’s faces in static stimuli. We produced shape-standardized facial models that were animated with male movement and assessed for flirtatiousness by 16 women and attractiveness by 47 women. In fertile phases of the menstrual cycle, women showed stronger preferences for flirtatious movement, but not for absolute movement. These data show that women (1) recognize specific mating-relevant social cues in male facial movement and (2) are differentially influenced by these cues at different phases of the menstrual cycle. This preference for flirtatiousness may promote the adaptive allocation of mating effort towards men who are, in turn, likely to respond positively.