The researchers think the finding applies to human brains. "Aggression occurs among virtually all vertebrates and is necessary to get and keep important resources such as mates, territory and food," said study team member Craig Kennedy, professor of special education and pediatrics at Vanderbilt University in Tennessee. "We have found that the reward pathway in the brain becomes engaged in response to an aggressive event and that dopamine is involved."
Many researchers believe violence in humans is an evolved tendency that helped with survival.
"Aggressive behavior has evolved in species in which it increases an individual's survival or reproduction, and this depends on the specific environmental, social, reproductive, and historical circumstances of a species. Humans certainly rank among the most violent of species," says biologist David Carrier of the University of Utah.