Do we know yet if it’s nature or nurture?
Posted May 29, 2013
Incidents like this always inspire questions about whether violent intent points to a born criminal or an environmental influence, such as aggressive role models, violent video games, or incessant bullying. Although we know little as yet about Acord, a new book by Adriane Raine, The Anatomy of Violence, offers some of the latest research in neuroscience on the issue.
Anyone who has followed Raine’s work over the past two decades has been waiting for this book.
Raine is a neuroscientist at the University of Pennsylvania, and he was among the first to use modern brain scans exclusively on murderers. He got his start in neurodevelopmental criminology by attaching sensors to inmates’ skin to measure their agitation when he made a loud sound. He found that some offenders had a low startle response.
In another study, Raine discovered that children from a small island who had slower heart rates and reduced skin responses to loud noises got into more trouble than other children. However, nutrition and improved education helped to reduce criminality for such children later in life.
Raine thought that because these children did not experience normal fear or distress, perhaps they did not learn from the consequences of risky behavior. They also did not learn empathy. Callous behavior and a lack of emotion in the same child seemed to predict those who would later become liars, thieves, and cheaters.
Raine’s findings coincided with other research on children who were at risk for becoming adult psychopaths. While adolescent misbehavior is often labeled as a conduct disorder – a temporary condition – one group of researchers found that impulsivity and hyperactivity coupled with callous/unemotional attitudes revealed budding psychopaths. These children also exhibited grandiosity, irresponsibility, and susceptibility to boredom.
Raine surmised that some of these behaviors could indicate something amiss in the brain. In 1997, with positron emission tomography (PET) that tracked the volume of blood (and oxygen) flowing through various brain regions during specific activities, Raine compared 41 murderers against 41 matched controls. He found brain deficits or abnormalities in most of the violent individuals.
These deficits showed up in the limbic system, corpus callosum (which connects the brain halves), left angular gyrus, and areas of the prefrontal cortex, where executive decisions are made and inappropriate behavior inhibited.
These abnormalities, Raine realized, might allow people to be impulsive, fearless, unresponsive to aversive stimulation, and less able to process emotional information or make socially correct decisions about aggression. Even murderers from seemingly adjusted backgrounds were adversely affected.
Raine also compared “predatory” and “affective” (or proactive and reactive) murderers. The predatory killers’ prefrontal cortex was similar to a normal brain, which indicated that predators could voluntarily regulate their behavior.
However, both groups showed more activity than did control subjects in the limbic system’s amygdala-hippocampal complex. Raine’s team speculated that this condition might predispose this group toward a more aggressive temperament. He offers quite a bit more research on this in his book.
Raine is convinced that while there is an environmental element to violent behavior, biology plays a strong role. He doesn’t believe that biology is destiny, but he states that “there are multiple health-related factors that occur right at birth and even before birth that are architects in shaping the landscape of violence.”
For example, Raine documents research on the links between smoking or drinking while pregnant and the increased odds of those women’s children being violent later in life. Specific birth complications and attachment issues are also implicated. “Biological and social processes are inextricably linked,” Rained observes, so “a true appreciation of the biology of violence needs to take this mix into full consideration.”
A single factor, he cautions, such as prefrontal dysfunction, would not make someone become a criminal offender, but a constellation of red flags might overwhelm a given individual.
“What if all the boxes were checked?” Raine said on NPR. “What if you had birth complications, and you were exposed to toxins, and you had a low resting heart rate, and you had the gene that raises the odds of violence, et cetera, et cetera…. Then how in the name of justice can we really hold that individual as responsible as we do ... and punish them as much as we do?"
In the book, he wisely compares cases in which the same brain damage, or scan results, or upbringing produced quite different results. Not everyone who experienced the same frontal lobe damage that the famous Phineas Gage did, for example, turned out like him – even if their personality dramatically changed as his did.
In other words, it’s complicated. There might not be a “born criminal,” but there appear to be biological conditions that make some people more likely to become one.
Raine wants readers to understand that there is no simple answer to the nature/nurture question. In fact, Raine himself has similar brain scan and IQ results as serial killer Randy Kraft. Raine attributes the difference in where each of them ended up to the presence or absence of “protective” social and environmental factors. This would include solid relationships and a sense of security. It would also include the person’s processing of those factors.
“So, yes,” he states, “individual genes are important – but in a specific social context.”
Raine points out that we are only now on the threshold of piecing together the puzzle of the neuro-anatomy of violence, but we know enough to design treatments and encourage greater awareness in the legal system.
In fact, researchers in the UK have worked on a “psychopath test” for kids. Using functional magnetic resonance imaging (fMRI) on children with conduct disorders, they’ve made an interesting discovery. They’ve found reduced activity in brain areas implicated in empathy when these subjects view photos of others in pain. This could be a neurobiological marker for later adult psychopathy.
However, this tool is not just for prediction; it selects children for treatment with the hope that early intervention can realign them with prosocial responses. Working with children believed to be at risk for adult psychopathy can have wide-reaching positive effects.
Anyone who truly seeks an answer to questions about nature vs. nurture should read Raine’s book. The Anatomy of Violence incudes many interesting studies, with provocative findings. He also raises important philosophical questions about what we could, and perhaps should, do with what we’re learning.