Does Masculinity Matter? The Contribution of Masculine Face Shape to Male Attractiveness in Humans Isabel M. L. Scott 1 , Nicholas Pound 2 , Ian D. Stephen 1 , Andrew P. Clark 2 , Ian S. Penton-Voak 1 * 1 School of Experimental Psychology, University of Bristol, Bristol, United Kingdom, 2 Department of Psychology, Brunel University, Uxbridge, United Kingdom Abstract 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 men’s 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. Citation: Scott IML, Pound N, Stephen ID, Clark AP, Penton-Voak IS (2010) Does Masculinity Matter? The Contribution of Masculine Face Shape to Male Attractiveness in Humans. PLoS ONE 5(10): e13585. doi:10.1371/journal.pone.0013585 Editor: Virginia J. Vitzthum, Indiana University, United States of America Received July 16, 2010; Accepted September 20, 2010; Published October 27, 2010 Copyright: ß 2010 Scott et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This research was supported by the University of Bristol. IDS is supported by the Economic and Social Research Council, UK. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: I.S.Penton-Voak@bristol.ac.uk Introduction Many researchers studying non-human mate choice have observed that exaggerated sex-typical male traits, such as large antlers and peacock’s tails, are attractive to females [1]. Authors have suggested that the growth of such traits is mediated by immune-stressing steroids such as testosterone, and that as only high quality males can ‘‘afford’’ exposure to immune stress, these traits signal high levels of immunocompetence [2–7]. Such perspectives have generated similar expectations regarding human mate choice – i.e. that masculine males should be attractive, and that this attractiveness is attributable to immunocompetence [8]. These proposals form the basis of a large literature on human preferences for facial masculinity [9]. More recently however, a number of authors have questioned immunocompetence perspectives on facial masculinity preferenc- es. Recent reviews of the animal literature present a complex and uncertain picture of the relationship between immunity, testoster- one and trait size [7,10]. In humans, preliminary evidence suggests there is an association between circulating testosterone levels and anatomical masculinity in faces [11], but the evidence for an association between either testosterone or masculinity and disease resistance is scant, inconsistent, and largely negative [7,12–20]. Even if masculinity does signal past disease resistance, it is unclear that females will, in general, benefit from attending to this signal, particularly if cues to current condition are available. Past disease resistance may be a weak predictor of current and future resistance, especially if pathogenic complexity is high, and pathogen fluctuation is fast (relative to host lifespan and generation length) [21,22]. Recent mathematical models of mate choice suggest that in most environments, females can reliably derive substantial fitness advantages from attending to current condition, but may gain little, if any, further benefit from simultaneously selecting mates on the basis of past immune function [21,22]. Thus, stable traits such as masculinity, which are not influenced by short-term fluctuations in adult health, should be of less importance to attractiveness than other more condition-responsive cues. This expectation is stronger in animals with long lifespans and slow reproduction, such as humans. Consistent with this reasoning, findings relating male attrac- tiveness to long-term health and/or stable facial traits have to date been equivocal [14,23–27]. In particular, reported mascu- PLoS ONE | www.plosone.org 1 October 2010 | Volume 5 | Issue 10 | e13585