The Anatomy of Violence (18 page)

We’ve also seen that there is not one but multiple brain areas which, when dysfunctional, can predispose one to violence. It’s not just the dorsal and
ventral regions of the prefrontal cortex that are dysfunctional, but also the amygdala, the
hippocampus, the
angular gyrus, and the
temporal cortex. Yet future research will show it’s even more complicated. The antisocial brain is a patchwork of dysfunctional neural systems and we are only just on the threshold of putting together these pieces to better understand it.

We’ve seen that poor brain functioning is not restricted to rare forms of violence. We’ve witnessed a frontal-limbic imbalance in relatively common forms of violence like
domestic abuse—the overactivation of the amygdala combined with under-activation of the regulatory frontal cortex. Increasingly, the scope of functional
brain imaging research is seeping into our personal lives. We are detecting a network of brain areas that unite in shaping the
moral decisions we make on a daily basis—brain areas that are just not functioning normally in “morally insane”
psychopaths and serial killers like Jolly Jane
Toppan. These individuals lack the
feeling
of what is moral, and that partly accounts for their inexplicably egregious behavior.

But let’s return to our point of departure. What do we really make of the horrific homicides perpetrated by Randy
Kraft? We’ve seen how highly regulated and controlled this computing consultant was. Surely Randy had enough prefrontal control to keep his carnal desires in check. Randy was a heartless, cold-blooded killer—and I mean heartless almost literally. In our next stop through the body in this anatomy of violence we will leave the brain and travel to the heart of the matter—to the
cardiovascular and
autonomic nervous system.

Imagine committing a heinous crime that benefits you but brings harm to others. Putting a knife into a hateful husband who beats you. Strangling a belligerent boss at work. Breaking into a house at night and robbing it. Taking revenge on the man who stole your girlfriend. Embezzling millions of dollars from your company. Worse still, abducting, torturing, raping, and killing innumerable strangers, one by one.

Think hard about it, putting yourself into the actual situation. You’ve been drinking late at night on campus and your passion and mind have gotten out of control. Your girlfriend seemed bored with you, started making eyes at other guys, then gave some lame excuse to go. She jilted you right there at the bar. You’d really wanted sex with her that night and now you feel frustrated and angry.

You are walking back to your dorm and it’s late at night. Then, not far ahead, you see a pretty student. You increase your pace to catch up, but keep a safe distance and walk softly so as not to make too much noise. As you come to the part of the path that breaks away from the buildings and moves into the trees, shrubs, and bushes, you catch up with her. You look quickly over your shoulder and no one is there. You grab her from behind. You place one hand on her mouth and shove her into the bushes and onto the ground. You take out a knife and threaten to take her life unless she performs specified sex acts with you. You
rape her. You can hear and feel her heart beating, loud as thunder in her terror, and it turns you on. Then, with one hand over her mouth, you take the knife and stab her through the heart as you gaze into her eyes to watch her expression of utter and complete fear, see her pupils contract, feel her body writhe, and hear her breathing shorten.

After committing the crime you attempt to cover your tracks. But the next day the police arrive outside your door. You are arrested. You must create an alibi and stick with it as you are grilled by suspicious authorities, keeping track of the lies, knowing that one false move could send you to the death chamber.

What’s going on inside you? What’s going on inside an actual perpetrator? I want to argue in this chapter that you and a real-life criminal radically differ—or at least I hope you do. It’s likely that you would perspire and your heart would quicken when you initially contemplated raping that girl, or during the interrogation. You may have been slightly nauseated just reading what I asked you to envision. Even the thought of it probably evoked negative emotions like disgust. But many violent offenders barely break a sweat when they violate the law, no matter how grave the transgression.

You have a conscience that was prickled at just the
thought
of committing the act, let alone the actual commission and completion. Others do not. You have a heart, while others are heartless. I’ll argue here that your conscience is predicated on the good functioning of your
autonomic nervous
system, a part of the body sometimes referred to as the “visceral” nervous system due to its key role in emotion. The most important breakthrough in our understanding of this region of the anatomy of violence is that the nervous system of some offenders is simply not as “nervous” as the rest of ours. It confers on them a
fearless, risk-taking, conscience-free personality that can result in criminal, violent, and even psychopathic behavior. They are biologically different from us. At the heart of this autonomic predisposition to violence, to which we first turn in this chapter, is the heart itself.

It may seem obvious to say that bomb-disposal experts and Theodore
Kaczynski have something in common. Ted Kaczynski, otherwise known as the Unabomber, started off as a professor at the University of California,
Berkeley, before embarking on his deadly career of violence, from 1978 to 1995. During this time he killed three people and injured
twenty-three others with bombs he sent in the mail or placed on planes. His first target was Northwestern University, and then he moved on to the University of Utah,
Vanderbilt, UC
Berkeley, the University of Michigan, and Yale. He left bombs on an American Airlines flight and sent a mail bomb to the president of United Airlines. His success is marked by his years-long evasion of one of the
FBI’s most expensive investigations in its history.

His big mistake came when he published a 35,000-word manifesto in
The
New York Times
and
The
Washington Post
. He had threatened to kill again unless it was published, and both the FBI and the attorney general acquiesced. The manifesto ranted against industrialized society, leftism, and scientists, and how they were controlling society and restricting freedom. In a flash of bad luck for Kaczynski, his estranged brother picked up the newspaper and happened to recognize some unusual words and phrases, such as “cool-headed logicians.” These phrases were reminiscent of letters he had received from Ted. Sections of the search warrant that al
lowed agents to search Kaczynski’s remote cabin in Lincoln, Montana, document that even then, many FBI experts didn’t believe that he was the author of the Unabomber manifesto. But all of that doubt was put to bed when FBI agents dropped in on him in 1996 and happened to notice a live bomb on the table together with the manifesto.

So, outside of the obvious, what would Ted Kaczynski have in common with a bomb-disposal expert? One key trait: in dealing with deadly contraptions both need nerves of steel and a certain degree of fearlessness. One British Army bomb-disposal expert working in Bosnia reflected on his job in this way: “It sounds dangerous but … I’ve not been in any situations where I felt in danger.”
¹
He is able to put that fear aside. Furthermore, both
bomb-disposal experts and serial killers are intelligent. Kaczynski was a child mathematics prodigy who went to
Harvard University at the tender age of sixteen. After gaining his PhD in mathematics from the University of Michigan, he was welcomed into a professorship at UC Berkeley. His IQ was above the genius level
²
—he scored 167 at age eleven.
³
Despite the despicable nature of Kaczynski’s acts, he, like a bomb-disposal expert, was an intelligent and, in many ways, a
highly rational individual.

But digging a bit deeper into the biology that our “test subjects” share, we find something else in common—a low resting
heart rate. Some people kill in such a manner that we call them cold-blooded killers
without thinking too much about the term. Yet what if this description turns out to be more literal than figurative?

In the anatomy of violence, the heart is a central organ orchestrating the tendency to
antisocial and violent behavior. As we so often do in biology, let’s start with
animals.
Rabbits who are
aggressive and dominant indeed have lower resting heart rates than subordinate, nonaggressive rabbits.
⁴
Furthermore, when dominance in these rabbits is experimentally manipulated, heart rate goes down as dominance goes up. The same relationships have been found throughout the animal kingdom in macaques,
baboons, tree shrews, and
mice.
⁵

Yet the idea that a
low heart rate can raise the odds of someone becoming antisocial and violent may strike you as something too simple to believe.
⁶
In an age of powerful and sensitive diagnostic tools like functional
brain imaging, there is something crude about linking violent behavior with a biomarker that is so astonishingly simple and easy to measure. Does this claim for the biology of crime and violence stand up to serious scientific scrutiny?

In my first research as a PhD student, at
York University, in England, I found that a low resting heart rate characterizes antisocial schoolboys.
⁷
I found the same result when I moved to Nottingham University.
⁸
Maybe it was a fluke? So when I moved to the
University of Southern California my colleagues and I conducted a meta-analysis of the heart rate–antisocial relationship. This involved us taking into account
all
studies we could find that had investigated this issue in child and adolescent samples.
⁹
We found forty publications, involving a total of 5,868 children. Pooling all studies gives you a much clearer view of the true picture.

What stood out clearly was that antisocial kids really do have lower resting heart rates.
¹⁰
We also looked at heart rate during a stressor—for example, while the subject was waiting for a medical exam. In the laboratory, kids would be asked to do a difficult mental arithmetic task like counting backward in sevens from 1,000. If you don’t think it’s all that stressful, just try it! In these cases involving stress, the overall differences become even larger.

In our meta-analysis, resting heart rate explained about 5 percent of the differences between subjects in antisocial behavior. That might not
seem like much to you, but put into medical context, the relationship is strong.
¹¹
It’s much stronger than the relationship between smoking and lung cancer, or the effectiveness of taking aspirin to reduce the risk of death from a
heart attack, or antihypertensive medication and reductions in strokes. Each of these are important and powerful relationships in the medical world, and in each case they are dwarfed by the strength of the heart rate–
antisocial relationship.
¹²

In fact, to get something as strong as the heart rate–antisocial relationship, you have to turn to the effect of nicotine patches in reducing smoking, or the ability of SAT scores to predict later college GPAs. If we now turn to resting heart rate during a stressor, this seemingly innocuous biomarker suddenly explains 12 percent of the variation that exists among us in antisocial behavior. This is as strong as the ability of mammograms to detect breast cancer, the accuracy of home pregnancy test kits, and success of sleeping pills in improving chronic insomnia. It’s hard to ignore these medical relationships. It’s equally hard to ignore the relationship between heart rate and antisocial behavior. It’s clinically meaningful and significant.

It is not that low heart rate characterizes only one subgroup of antisocial kids. It applies to young as well as older children, and to girls as well as boys. So boys with low heart rates are more antisocial than boys with high heart rates. Girls with low heart rates are more antisocial than girls with high heart rates.
¹³

However, heart rate may partly explain the
gender differences in antisocial behavior. If you take your pulse using your watch, count the number of beats in one minute, and compare it with your opposite-sex sibling or partner’s pulse, you will likely find that if you are female, your heart rate is several beats a minute higher than your male counterpart’s. Males in general have lower heart rates than females; it’s a robust finding.
¹⁴
There is the same sex difference in antisocial behavior. The sex difference in heart rate is in place as early as age three, with boys having a heart rate that is 6.1 beats a minute lower than girls.
¹⁵
This sex difference in heart rate starts just before sex differences in antisocial behavior begin to emerge.
¹⁶
The strong and replicated sex difference in heart rate provides one intriguing clue as to why
men commit more crime than women—they have lower heart rates.

Let’s shift from comparing genders to comparing generations. Twin studies have repeatedly found substantial
heritability for resting heart rate.
¹⁷
They have also found that the offspring of criminal parents
have low resting heart rates.
¹⁸
Given the fact that there is significant heritability for childhood aggression and adult antisocial behavior, and given that there is transmission of antisocial behavior from parent to child, low heart rate may be one of the heritable mechanisms that account for the transmission of antisocial behavior from one generation to the next.

A lot of studies have measured heart rate and antisocial behavior concurrently, at the same point in time. But a stronger design would be to assess heart rate
early in life—and then show that it’s related to antisocial behavior at a later age. That’s called a
prospective longitudinal design. Five such longitudinal studies from England,
New Zealand, and Mauritius have indeed confirmed that low
heart rate in childhood—as early as age three—is a
predictor
of later delinquent, criminal, and violent behavior.