Neuroendocrine Mechanisms Underlying Male Aggression

In free-living animals, aggressive behaviors by males often serve to maintain resources the male will need to attract and protect females. In many human cultures, the frequency of murders of males by unrelated males depends on age. Young men between the ages of approximately 13 and 20 tend to be the most violent. That is, as soon as testosterone arrives in significant concentrations in the brain and for years thereafter, violent aggression is more likely. In this public symposium I will address two questions: First, how is it possible to increase testosterone-fueled aggressive behaviors? My four levels of answers to this question do not exclude each other: (1) higher testosterone concentrations; (2) higher concentrations of testosterone receptors; (3) adjustment of neuronal nuclear proteins to make testosterone receptors more effective; and (4) hooking up testosterone-facilitated neurons so that they trigger aggression more effectively. Second, what does testosterone do, exactly, in the nerve cell ? Answer: it works through two routes in parallel, one route directly affecting gene expression in the nerve cell nucleus, and the other route initiated at the nerve cell membrane. Understanding all of these ways that testosterone fuels aggression may suggest antidotes: pharmacological, psychological and/or cultural.