>A revisionist picture also applies to testosterone, the biological factor probably most immediately associated with violence – after all, in the vast majority of social species, and in every culture examined, males are more likely to be aggressive than females. Moreover, as something of a gold standard in endocrinology, subtraction of the hormone (i.e., through surgical or chemical castration) decreases average levels of aggression in humans and other mammals. Finally, if testosterone-like androgens are administered in high amounts (for example, as among athletes who are steroid abusers), levels of aggression typically rise.
>The malign effects of testosterone run even deeper, if more subtly than that. The hormone decreases trust and biases people to perceive neutral faces or circumstances as threatening, thus lowering the threshold for provocation. Empathy is inhibited as well, and the accuracy of Theory of Mind about other people's thinking declines. Testosterone also biases toward risk-taking, makes individuals less sensitive to the typically constraining effects of negative reinforcement, and less cooperative because of an exaggerated sense of the importance and accuracy of one's thinking (Hermans et al., 2006; Bos et al., 2010, 2012). None of these effects auger well for reducing interpersonal and intergroup conflict.
