Gender differences in the interrelations between digit ratio, psychopathic traits and life history strategies

The primary purpose of this study was to assess the relationship between prenatal exposure to sex hormones, as measured by digit ratio (2D:4D), and psychopathic personality traits while controlling for the confounding effect of life history strategy. The secondary purpose was to confirm the hypothesis that primary and secondary psychopathy reflect a faster life history strategy. In a nonclinical sample of 137 volunteers, we measured the right and left hand digit ratios, personality traits reflecting primary and secondary psychopathy, and life history strategies. In a hierarchical regression analysis, males with lower levels of prenatal testosterone exposure, as measured by the left hand 2D:4D, scored higher on the subscale measuring primary psychopathy. Neither the right hand 2D:4D nor the left hand 2D:4D were significant predictors of secondary psychopathy. In the female subsample, digit ratios did not correlate with either primary or secondary psychopathy. Males with faster life history strategies scored higher on both primary and secondary psychopathy. By contrast, among the female participants, there was no significant correlation between the life history score and primary psychopathy, and the correlation with secondary psychopathy was significant but relatively weak. These findings suggest that the neurodevelopmental pathways to psychopathy may differ according to sex.