When most people think of aggression, they think of road rage, physical fights, and violent crime. However, not all aggression is bad. Aggression is adaptive, helping people and animals alike to guard their homes from intruders and protect their children from threats. Problems arise when aggression is taken too far, escalating abnormally and becoming violent. Neuroscientists are working to identify brain regions, neurotransmitters, and genes that are involved in escalated aggression and violence. This research may one day help identify individuals at risk of developing dangerous behaviors and new treatments to prevent such episodes in at-risk individuals.