Effect of Partnership Status on Preferences for Facial Self-Resemblance.

Self-resemblance has been found to have a context-dependent effect when expressing preferences for faces. Whereas dissimilarity preference during mate choice in animals is often explained as an evolutionary adaptation to increase heterozygosity of offspring, self-resemblance can be also favored in humans, reflecting, e.g., preference for kinship cues. We performed two studies, using transformations of facial photographs to manipulate levels of resemblance with the rater, to examine the influence of self-resemblance in single vs. coupled individuals. Raters assessed facial attractiveness of other-sex and same-sex photographs according to both short-term and long-term relationship contexts. We found a preference for dissimilarity of other-sex and same-sex faces in single individuals, but no effect of self-resemblance in coupled raters. No effect of sex of participant or short-term vs. long-term attractiveness rating was observed. The results support the evolutionary interpretation that dissimilarity of other-sex faces is preferred by uncoupled individuals as an adaptive mechanism to avoid inbreeding. In contrast, lower dissimilarity preference of other-sex faces in coupled individuals may reflect suppressed attention to attractiveness cues in potential alternative partners as a relationship maintenance mechanism, and its substitution by attention to cues of kinship and psychological similarity connected with greater likelihood of prosocial behavior acquisition from such persons.

Sexual dimorphism and personality attributions of male faces.

Individuals tend to judge personality traits on the basis of physical characteristics, particularly facial traits, although this phenomenon has been mostly studied in relation to the halo effect of attractiveness. However, there are other facial traits which may also have an impact on personality attributions; here, we focused on masculinity. We carried out principal component analysis (PCA) of 15 anthropometric measurements from 71 male faces, resulting in three components: Face Height (C1), Inner Face Breadth (C2), and Cheekbones-Jaw Prominence (C3). The targets' photographs were rated by 210 women and 177 men on scales for masculinity, attractiveness, and nine psychological characteristics (selected Cattell's factors): Warmth, Reasoning, Emotional Stability, Dominance, Liveliness, Rule-Consciousness, Social Boldness, Abstractedness, and Privateness. We found that masculinity correlated positively with ratings of Dominance and Social Boldness and that masculinity rated by men correlated positively with ratings of Emotional Stability and Privateness. We found no relationship between masculinity rated by women and the PCA components, while masculinity rated by men correlated negatively with C2 (possibly related to babyface features) and positively with C3 (which included features developed under the control of testosterone, such as jaw prominence). Our results imply sex differences in masculinity ratings. In particular, men used Cheekbones-Jaw Prominence and Inner Face Breadth as cues for masculinity judgments; on the other hand, women apparently perceive masculinity in a more holistic way.

Pattern of money allocation in experimental games supports the stress hypothesis of gender differences in Toxoplasma gondii-induced behavioural changes.

Latent toxoplasmosis has been previously found to cause behavioural and personality changes in humans, which are specific for each gender. Here we tested the stress hypothesis of these gender differences based on the assumption that latent toxoplasmosis causes long-term subliminal stress. In line with this hypothesis, the gender difference will appear specifically in situations with interpersonal context because in contrast to the typical individualistic coping style of men, women have a tendency to express elevated prosocial behaviour under stress. Altogether 295 biology students (29/191 females and 27/104 males infected by T. gondii) played a modified version of the Dictator Game and the Trust Game. As predicted, a gender difference in the effect of latent toxoplasmosis was found for the measure of reciprocal altruism in the Trust Game (p = 0.016), but both genders appeared less generous when infected in the Dictator Game modified to minimize social connotation (p = 0.048).