Take sixty seconds to check your heart rate. If it’s lower than sixty beats per minute, you might be “physiologically predisposed” to commit violent crimes.
A Biological Basis for Criminal Behavior?
Scientists have long entertained the idea that there is a biological basis for criminal behavior. A number of studies in the past have linked low resting heart rates to antisocial behaviors, but most involved small sample sizes and collections of observations were limited to short periods of time.
In any case, a group of researchers from the Karolinska Institute near Stockholm recently decided to examine data collected by the Swedish government for “conscription assessments” of young men entering the armed forces. The data, which included records of the resting heart rates of over 700,000 people, spanned multiple decades.
The researchers worked to control for all kinds of variables that could potentially impact either a man’s heart rate or risk of criminal behavior, such as height, weight, blood pressure, body mass index, socioeconomic status, IQ, psychiatric health, and physical fitness (as determined by an exercise test). Still, they found that subjects with the lowest resting heart rates at age 18 were definitively more likely to engage in criminal behavior as they got older.
The study, published in Jama Psychiatry, divided the men’s data into five groups based on their heart rates. The men in the slowest group had heart rates of between 35 and 60 beats per minute. The heart rates of the men in the fastest group were between 83 and 145 beats per minute. Upon analysis, researchers determined that the men with the slowest heart rates were forty-nine percent more likely to commit violent crimes than the fastest group, as well as thirty-three percent more likely to be convicted of nonviolent offenses. They were also forty-one percent more likely to be injured in an assault and thirty-one percent more likely to be injured in an accident.
Why the Connection between Heart Rate and Criminal Behavior?
So why might men with lower resting heart rates be predisposed to criminal behavior? Scientists hypothesize that it could have something to do with a slow heart rate indicating “lower levels of physiological arousal.” This could mean that men with slow heart rates either seek out more dangerous and more illegal activities to feel stimulated, or that their fear response mechanisms are muted, which could result in pushing risky or stressful situations farther than the next guy.
However, these are mostly just guesses, and more work needs to be done in order to establish the scientific ties. A similar study has not yet been conducted with respect to girls and women. But some research has utilized stimulant medications to increase heart rate to improve behavior.
There is also a lot to focus on in regards to ethics, as these findings relate to the justice system. Does being born with a low resting heart rate mean you’re simply doomed to criminal behavior, or can you avoid such a fate through care and discipline? (It’s relevant to note that criminals were the minority in this research–only six percent of the men studied were convicted of a violent crime.) On the flip side, does a biological predisposition to criminal behavior, in any way, excuse you from the offense you may commit?
