Second to fourth digit ratio and cooperative behavior.

A low second to fourth digit ratio (2D:4D) has been related to high testosterone levels and to markers of high status. In a social dilemma context status can be obtained either by acting egoistically (i.e. not contributing one's share) or by acting altruistically (i.e. contributing more than one's fair share). We therefore predicted that a low 2D:4D would be associated with high levels of egoism and altruism and low levels of common cooperativeness (i.e. contributing exactly one's fair share). We found the exact opposite: participants with a low 2D:4D were more likely to act cooperatively and less likely to act altruistically and egoistically. These findings suggest that: (1) there might be a high and a low testosterone strategy to gain status and (2) the high testosterone strategy is characterized by a preference for normative behavior.