Digit ratio (2D : 4D) and prosocial behaviour in economic games: no direct correlation with generosity, bargaining or trust-related behaviours

Abstract

Prenatal exposure to sex hormones exerts organizational effects on the brainwhich have observable behavioural correlates in adult life. There are reasonsto expect that social behaviours—fundamental for the evolutionary successof humans—might be related to biological factors such as prenatal sex hor-mone exposure. Nevertheless, the existing literature is inconclusive as towhether and how prenatal exposure to testosterone and oestrogen, proxiedby the second-to-fourth digit ratio (2D : 4D), may predict non-selfish behav-iour. Here, we investigate this question using economic experiments withreal monetary stakes and analyse five different dimensions of social behaviourin a comparatively large sample of Caucasian participants (n= 560). For bothmales and females, our results show no robust association between right- orleft-hand 2D : 4D and generosity, bargaining or trust-related behaviours. More-over, no differences in behaviour were found according to sex. We concludethat there is no direct correlation between 2D : 4D and these social behaviours.