Bad to the bone: facial structure predicts unethical behaviour

Abstract

Researchers spanning many scientific domains, including primatology, evolutionary biology and psychology, have sought to establish an evolutionary basis for morality. While researchers have identified social and cognitive adaptations that support ethical behaviour, a consensus has emerged that genetically determined physical traits are not reliable signals of unethical intentions or actions. Challenging this view, we show that genetically determined physical traits can serve as reliable predictors of unethical behaviour if they are also associated with positive signals in intersex and intrasex selection. Specifically, we identify a key physical attribute, the facial width-to-height ratio, which predicts unethical behaviour in men. Across two studies, we demonstrate that men with wider faces (relative to facial height) are more likely to explicitly deceive their counterparts in a negotiation, and are more willing to cheat in order to increase their financial gain. Importantly, we provide evidence that the link between facial metrics and unethical behaviour is mediated by a psychological sense of power. Our results demonstrate that static physical attributes can indeed serve as reliable cues of immoral action, and provide additional support for the view that evolutionary forces shape ethical judgement and behaviour.

Figure 1.

Study 1: mean facial WHR (±s.e.m.) of men and women separated by deception behaviour. Filled bars, no deception; unfilled bars, deception.

Figure 2.

Study 2: mediation model. Coefficients are standardized βs. Numbers to the right of the slash represent the standardized β in the simultaneous regression analysis. Symbols: *p < 0.05; **p < 0.01; ^†p < 0.10.