Aggression stems from specific neural circuits and hormones, not a single brain area—here's how sunlight, heat therapy, and supplements like ashwagandha can reduce aggressive impulses. Learn the biology behind reactive vs. proactive aggression and why estrogen (not testosterone) drives violent behavior in both sexes. The ventromedial hypothalamus, containing only ~3,000 neurons, is necessary and sufficient to generate aggressive behavior when estrogen receptors are activated.