Facial cues to physical strength increase attractiveness but decrease aggressiveness assessments in male Maasai of Northern Tanzania

Male physical formidability may reflect capacities to provision and protect, resource holding potential, and social status. Handgrip strength (HGS) is a robust measure of overall muscular strength and function that correlates positively with ratings of male facial attractiveness and dominance. Here, we examine strength, attractiveness, and aggressiveness assessments as a function of facial cues to HGS in a sample of male Maasai of Northern Tanzania. Adult Maasai (56 women, 40 men) rated three strength-calibrated facial morphs of Maasai men. These morphs were constructed by performing a geometric morphometric shape regression on HGS using digital images of 54 men (20–29 years). Participants judged facial morphs calibrated to greater HGS higher on strength and attractiveness, but lower on aggressiveness. The accurate assessment of male Maasai physical strength from facial cues and the corresponding attractiveness assessments of strength cues are consistent with evolutionary predictions and previous research. The situation is less clear for the association of facial strength cues with the assessment of aggression. Future research should consider the possibility of a (feature-based) perceptual overgeneralization, especially in the interpretation of facial aggressiveness judgments, in addition to population-specific influences, and distinguish them from facial cues that indicate behavioral dispositions. Collectively, the findings of the present study corroborate the suggestion that the Maasai are sensitive to facial cues of strength and use these cues in social assessments.