Who is the fairest of them all? The independent effect of attractive features and self-perceived attractiveness on cooperation among women.

The present paper analyses the extent to which attractiveness-related variables affect cooperative behaviour in women. Cooperativeness is evaluated through a Prisoner's Dilemma Game (PDG). We consider several morphometric variables related to attractiveness: Fluctuating Asymmetry (FA), Waist-Hip Ratio (WHR), Body Mass Index (BMI) and Facial Femininity (FF). These variables have been shown to predict human behaviour. We also include as a control variable a score for Self-Perceived Attractiveness (SPA). We test differences in these variables according to behaviour in the PDF. Our results reveal that low FA women cooperate less frequently in the PDF. We also find that women with lower WHR are more cooperative. This result contradicts the expected relation between WHR and behaviour in the PDF. We show that this effect of WHR on cooperation operates through its influence on the expectation that participants hold on the cooperative intent of their counterpart. In addition, we show that the effect of attractive features on cooperation occurs independently of the participants' perception of their own appeal. Finally, we discuss our results in the context of the evolution of cooperative behaviour and under the hypothesis that attractiveness is a reliable indicator of phenotypic quality.