Does masculinity matter? The contribution of masculine face shape to male attractiveness in humans

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.

Figure 1. Masculinity, measured, rated and morphed: examples of dimensions.

To preserve anonymity of participants, these faces are composites rather than real individuals. a) Morphological masculinity. Examples of faces scoring low (left) and high (right) on this measure. b) Rated masculinity. Examples of faces rated as low (left) and high (right) masculinity. c) Digitally morphed masculinity. Example of a face morphed in the feminine (left) and masculine (right) direction.

Figure 2. Colour variation: examples of stimuli.

a) Faces scoring low (left) and high (right) for lightness (L*). b) Faces scoring low (left) and high (right) for redness (a*). c) Faces scoring low (left) and high (right) for yellowness (b*).