What is science revealing about the nature of the criminal mind? Adrian Raine, a professor at the university of Pennsylvania, is an expert in the expanding field of “neurocriminology.” He has written The Anatomy of Violence, a sweeping account of crime’s biological roots, including genetics, neuro-anatomy and environmental toxins like lead. He spoke with Mind Matters editor Gareth Cook.

Gareth Cook: The study of the links between biology and violence has a controversial and somewhat unsavory past. Can you tell me a bit about that, and what convinced you it is still a worthy topic?

Adrian Raine: Neurocriminology pushes a lot of peoples’ buttons for lots of different reasons. There’s the obvious historical misuse of biological research – think of the eugenics movement in this country when we sterilized mentally retarded people in an attempt to raise the overall IQ of the general population. Think of Hitler and the genocide that took place. So there’s always a potential for misuse, so of course we must tread carefully. But we also have to move forward to find new solutions to old problems, and neuroscience is offering us new vistas into the criminal mind that may in the future help us reduce violence. We need not resort to drastic measures to change the brain as we did in the past with frontal lobectomies.

There are other reasons for antagonism to a biological approach. Social scientists are concerned that shiningthe spotlight on the biological causes of crime will shift attention away from important social problems like bad neighborhoods, poverty, and racial discrimination. I can understand their perspective, and they are absolutely right that we need to eradicate these social inequalities. But unless we also tackle biology, violent crime is never going to go away.

The free-will debate also raises its ugly head. People are concerned about chalking up a good portion of crime and violence to genetics and biology — what does that say about choice and agency? Was it all determined from the get-go? Are we just gene machines destined to play out our programed nature in life? Let’s face it, nobody wants to hear that, do they?

And that brings us to politics. Conservatives don’t like my work because they think it will encourage a soft approach to crime – we’ll blame crime on the brain, not the person. But liberals don’t like it either because they think civil liberties are at stake – we’ll use biomarkers to identify who is at risk for violence and lock them up before they have committed a crime, the pre-emptive strike.

Then at the end of the day we get down to plain old interdisciplinary rivalries. Neurocriminology is a new approach that is attracting attention, and threatening the status quo. Other academics can get miffed that their own work doesn’t reach the spotlight. They’re human after all. They want to protect their own turf, and you can understand their frustration that their good science might not be getting the attention it deserves.

That’s a heck of a lot of baggage. So why, despite all this, have I thought for the past 35 years that it’s a worthy topic? Because science shows that 50 percent of the variance in crime is under genetic control. OK, so we could turn our backs on biology. Let’s pretend it doesn’t exist. Like an ostrich, we could bury our heads in the sand and pretend the hunter is not there. But the tragedy is that in our blind ignorance we’ll never have the biological insights to stop future violence. And you’d better watch out – the ostrich may get shot.

Cook: What are the strongest links between biology and violence, the results that are most widely accepted?

Raine: There’s no question whatsoever that genetic influences play a very significant role in shaping crime and violence. That can no longer be disputed. What can be debated is what specific genes are involved – and in what way. The gene that codes for the enzyme MAOA does seem to be involved at some level, but there’s still a long way to go in the hunt for genes that predispose to violence.

There’s also an explosion of brain imaging research. The most replicable finding so far is dysfunction to the prefrontal cortex, the “guardian angel” in the brain that controls our impulsive behavior and regulates our emotions. Damage that emergency brake on behavior, and explosive violence is not far away.

But you know, the neurobiology of violence is far from simple. We’re clearly going to find that it’s enormously complex. At the end of the day we’ll find that multiple brain systems are in on the act.  One prime suspect in shaping psychopathic behavior is the amygdala – the seat of emotion. Psychopaths have a core emotional deficit – they lack conscience, remorse, and guilt. They just don’t feel feelings the way we do. Several studies are documenting volume reductions in this brain structure in psychopaths. The amygdala is also less activated in psychopaths when they contemplate moral dilemmas. It’s as if psychopaths don’t have the feeling for what is right and wrong – even if they know it at a cognitive level. Still, we are just at the very beginning of a long journey into understanding the brain basis to violence. We have a very long way to go.

What else at the biological level? Lots of things. At a psychophysiological level something as simple as low resting heart rate is probably the best-replicated biological correlate of antisocial and aggressive behavior in children and adolescents. We think it’s a marker for fearlessness and impulsive stimulation-seeking. High testosterone and low cortisol are hormonal candidates. In terms of neurotransmitters, low serotonin is a well-replicated correlate of impulsive violence.

But health factors are really important too, and in a way the seeds of sin are sown pretty early on in life. Mothers who smoke or drink during pregnancy are much more likely to have babies who grow up to become violent offenders. Poor nutrition during pregnancy also raises the odds of later offending. Even birth complications – especially when combined with social risk factors like the maternal neglect – raises the odds of adult violence. And let’s not forget environmental toxins like lead. They damage the brain, and not surprisingly are associated with antisocial behavior.

Cook: What do you think of the argument put forward by Steven Pinker in The Better Angels of Our Nature, suggesting that violence has dropped dramatically as our social structures have changed?

Raine: The Better Angels of Our Nature was a masterful thesis that to my mind was right on the mark in its main argument – violence has indeed dropped over time. Sure, social structures that provide order and help contain violence have surely been a part of this, but the idea I particularly resonated to in Pinker’s book is the idea that thinking and reasoning has been one of our better angels. We’ve become smarter, more educated, and better able to reason, and partly for that reason we’ve moved away from violence.

And that’s really why I wrote The Anatomy of Violence. I want more people to understand why people commit crime. I want them to know the brain mechanisms behind these acts, and what factors, including environmental influences, shape the brain processes that predispose to violence.

Back in 1993, when I wrote an academic book, I finished with the argument that world history has shown that as society becomes more ennobled and sophisticated in its scientific understanding, conditions like epilepsy and psychosis ceased to be viewed within a moral / theological context and more within the humanitarian context of treatment. I repeat that refrain in The Anatomy of Violence. It’s something I sincerely hope for, a more enlightened society that can learn from a new and exciting body of biological knowledge on what causes offending. Chalking a violent act up to “evil” is easy, but it’s thirteenth century thinking. We need to move on into a more scientifically enlightened future.

To stop violence we have to understand its causes. For the past century we focused all our attention to only one side of the coin, the social contribution. Now it’s time to flip the coin over and examine the biological contribution. Unless we do that, we’ll never have the full picture, and we’ll go on living out the disheartening headlines that we read in newspapers today.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist at the Boston Globe. He can be reached at garethideas AT gmail.com or Twitter @garethideas.