Digit ratio (2D:4D) predicts pro-social behavior in economic games only for unsatisfied individuals

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 are reasons to expect that social behaviors—which are fundamental for the evolutionary 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 prenatal exposure to testosterone and estrogen, proxied by the second-to-fourth digit ratio (2D:4D), may predict non-selfish behavior. Here, we investigate this question using economic experiments with real monetary stakes and analyzing five different dimensions of social behavior in a comparatively large sample of Caucasian participants (n=560). For both males and females, our results show no robust association between right- or left-hand 2D:4D and generosity, bargaining, or trust-related behaviors. Since 2D:4D is thought to be a marker for status, we set-up and test the hypothesis that 2D:4D explains prosocial behavior only for people with low subjective wellbeing who are in need for status. Using two different measures of subjective wellbeing, we find considerable support for our hypothesis, especially among males. These results contribute to the debate regarding the context-dependent interpretation of the effect of prenatal hormone exposure on behavior by suggesting that important moderating factors may explain the differing results in the literature. In particular, we uncover the importance of accounting for the subjective nature of need for status, which has been largely overlooked in previous work.