The Baltimore Sun uses a local murder to explore the question of what makes someone take a life, cross the line from angry person to violent killer. Baltimore has many residents who kill brazenly, without remorse. Are they born with something broken or missing in their brains – impulse control, perhaps, or a conscience? What’s the influence of their environment, of abusive parents, of dangerous neighborhoods, of violent video games? “The question of why we as human beings are violent is one of the great unanswered questions about us,” said Dr. Debra Niehoff, author of the book The Biology of Violence: How Understanding the Brain, Behavior, and Environment Can Break the Vicious Circle of Aggression.
Humans are born with the capacity for aggression for survival purposes, an evolutionary need to be able to face down attack from wild animals, or from others invading their territory. “You have to be able to defend yourself,” said Dr. Allan Siegel of the New Jersey Medical School. Some scientists are researching genetic variations that may be present in those who are prone to violence. In one study, researchers discovered that the same variation in one gene seemed to be found in most of the study subjects who had arrest records. Other scientists are looking at the brain’s neurochemistry to see whether long-term exposure to dangerous situations or abuse throws off the fight-or-flight response system, causing violent overreaction to minor provocations.