Altruistic face: experimental study on facial morphology and prosociality in Buryats of Southern Siberia

The aim of the present experimental study was to investigate possible associations between individual cooperativeness and facial morphology. Participants of the study were Buryats of Southern Siberia (males: N=98; females: N=89; mean age 20 ± 2y.). Individual cooperativeness was assessed in experimental economic game “Public Goods Game”, which was conducted “face-to-face”, in groups of 4 same-sex individuals, who were strangers to each other. The game involved real monetary pay-offs. In the course of the experiment such individual behavioral features as propensity for unconditional/conditional cooperation, selfishness, or free-riding were revealed. Facial shapes of participants were explored through anthropological photographs using geometric morphometrics, and via assessing standard facial indexes. As a result the relationship between facial shape and unconditional cooperation was identified and visualized. This relationship appeared only among males. The analysis of sex-specific facial traits of Buryats revealed that faces of male unconditional cooperators combined both male-specific, and female-specific facial features. This is the first study to investigate association between full facial shape and human cooperativeness.