Digit ratio (2D:4D) and pro-social behavior in economic games: No direct correlation with with generosity, bargaining, or trust-related behaviors

Abstract

Prenatal exposure to hormones, and to sex hormones in particular, exerts organizational effects on the brain and these have observable behavioral correlates in adult life. There 10 are reasons to expect that social behaviors—which are fundamental for the evolutionary 11 success of humans—might be related to biological factors such as prenatal sex hormone exposure. Nevertheless, the existing literature is inconclusive as to whether and how 13 prenatal exposure to testosterone and estrogen, proxied by the second-to-fourth digit 14 ratio (2D:4D), may predict non-selfish behavior. Here, we investigate this question 15 using economic experiments with real monetary stakes and analyzing five different 16 dimensions of social behavior in a comparatively large sample of Caucasian participants 17 (n=560). For both males and females, our results show no robust association between 18 right- or left-hand 2D:4D and generosity, bargaining, or trust-related behaviors. We conclude therefore that there is no correlation between 2D:4D and social behavior in 20 economic games.