Brain development and physical aggression: How a small gender difference grows into a violence problem

Abstract

Of the various behavioral differences between males and females, physical aggression is one of the largest. Regardless of gender, children’s physical aggressiveness peaks between two and four years of age but then starts diverging, as girls learn more quickly than boys to suppress such overt behaviors. By puberty there is a sizable gender difference in physical aggression and violence. Studies in rodents suggest that sex differences in aggression and rough-and-tumble play are mediated by the amygdala, whose volume in males is enhanced by prenatal testosterone. However, efforts to extend this model to humans have shown limited success. This paper takes a critical look at current assumptions about gender differences in aggression and their neural basis. Aggression and empathy are competing impulses that engage much of the same cortico-limbic circuitry and are highly sensitive to social factors and early adversity. Learning, or neuroplasticity, is both a primary cause and key intervention for minimizing male aggression and violence.