What is criminality?

Biochemical Abnormalities

Scientists have long sought an answer to the heritability of criminality. Early attempts to identify the roots of human criminal behavior were based on the concept of biological determinism,
which explains and justifies human behavior as strictly a reflection of inborn human traits, with little or no attention paid to psychological or environmental influences. For example, Italian physician Cesare Lombroso
reported in L’uomo delinquente (1876; The criminal man) that certain “inferior” groups, by virtue of their “apish” appearance, were in actuality evolutionary throwbacks with criminal tendencies. Since that time, however, more sophisticated scientific theories and methods have been developed to identify the multiple etiologies of human behavior, including criminality.

Among the best-known theories of human behavior to find support in the scientific community are those suggesting certain biochemical imbalances, particularly involving neurochemicals, potentially play a role in generating a wide range of abnormality. Neurotransmitters are responsible for activating behavioral tendencies and patterns in explicit areas of the brain, so it makes sense that imbalances in these chemicals might also negatively affect behavior.

In some research studies, decreased levels of the neurotransmitter serotonin have been discovered in people who are depressed or aggressive, have attempted suicide, or have poor impulse control, such as impulsive arsonists and children who torture animals. In other studies, though, normal levels of serotonin have been found in these same groups, as well as abnormal levels in normal groups. As well, abnormalities in the brain’s levels of dopamine (another primary neurotransmitter) have also been implicated in aggressive and antisocial behaviors, although studies have yielded mixed results. Put simply, the role of neurotransmitters, including serotonin and dopamine, in abnormal behavior remains controversial and likely does not adequately explain criminality without taking into account social and psychological influences.

Perhaps the most widely researched theories of criminality have addressed potential genetic influences. The majority of early investigations in this area examined the role of an abnormality of the sex chromosomes—47,XYY—involving the presence of an additional Y chromosome in an otherwise normal male karyotype. Beginning in the 1960s, Dr. Patricia Jacobs proposed that those males who possess this extra Y chromosome were overrepresented in prisons and mental institutions. She studied nine males (out of more than three hundred males in a maximum security prison) who had an XYY karyotype. These XYY males had above-average height (generally over six feet tall) and below-average intelligence, exhibited personality disorders, and were more prone to have engaged in antisocial acts leading to their incarceration. A number of studies also supported these early findings, which understandably generated considerable interest—and debate—into the abnormal behaviors potentially associated with a XYY condition. By the 1970s, multiple investigations into XYY males in various settings, not just prisons, yielded inconsistent findings with respect to behavior. In fact, the only dependable feature of XYY males, whether incarcerated or not, appears to be that of increased height. No definitive associations between XYY males and criminal behaviors have ever been absolutely demonstrated.

Another proposed genetic explanation for criminal behavior involves an abnormality in the enzyme monoamine oxidase A (MAOA). This important enzyme is responsible for degrading certain neurotransmitters, including dopamine and epinephrine. Theoretically, criminal behavior is more liable when the normal levels of neurotransmitters in the brain are disrupted, which in turn leads to behavioral alterations. To date, no definitive causal link to criminal behavior has ever been established in individuals with a MAOA abnormality.

The biology of criminality is comparable to the biology of aggression, with testosterone (or similar androgens) typically being referenced in order to explain belligerent male behavior. Yet defining male criminal behavior in terms of excessive testosterone, or another biochemical entity, has almost become a cliché, and one without solid scientific merit. A multimodal approach is instead preferable. Therefore, the roles of psychology and environment in criminal behavior must also be considered. When physiological dysfunction exists secondary to genetic dysfunction, cognitive deficits and impulsiveness may also coexist, which sets the stage for criminal tendencies to be acted out. First, a neural defect in almost any form is frequently associated with impatience, irritability, and impulsiveness. Next, misperceptions and ideation, symptoms associated with many different kinds of antisocial behavior, increase anxiety and the tendency to “act out” or “retaliate” for both real and imagined reasons. Finally, intellectual deficits not only diminish judgment but also lessen the person’s ability to acknowledge feelings and describe them verbally rather than through inappropriate actions.

Overall, genetic abnormalities clearly play a role in affecting numerous human characteristics, including mental capabilities and behavior, but to ignore psychology and environment in human characteristics is to be simplistic. After all, criminality refers to a violation of the law, and since there are numerous types of crimes and motivations for them (anger, revenge, financial gain), it is difficult to make claims of definitive, nonenvironmental links between biochemical disorders and criminal behavior without exploring all potential variables. In other words, the nature of human criminal behavior defies simple and straightforward explanations. The exact causes of aberrant behavior are complex and involve multiple influences, of which is genetics is one critical component.

Impact and Applications

Research into the biological and genetic causes of criminality entered the public spotlight starting in the early 1990s as part of the US government’s Violence Initiative, championed by then secretary of health and human Services Louis Sullivan. The uproar began when Frederick Goodwin, then director of the Alcohol, Drug Abuse, and Mental Health Administration, made comments comparing urban youth to aggressive jungle primates. The public feared that research on genetic links to criminality would be used to justify the disproportionate numbers of African Americans and Hispanics in the penal system. Psychiatrist Peter Breggin also warned that unproved genetic links would be used as an excuse to screen minority children and give them sedating drugs to intervene in their impending aggression and criminality. After all, forced sterilization laws had been enacted in thirty US states in the 1920s to prevent reproduction by the “feebleminded” and “moral degenerate.” In the early twenty-first century, the general public remains highly suspicious of any medical or genetic research that might be used to target and marginalize minority or disadvantaged groups as predisposed to “criminal” behavior. This is all the more the case as the Human Genome Project continues to discover genetic links to diseases and pathological behaviors.

In an era in which genes have been implicated in everything from bipolar disorders to the propensity to change jobs, the belief that genes are responsible for criminal behavior is very enticing. However, this belief may have severe ramifications. To the extent that society accepts the view that crime is the result of pathological and biologically deviant behavior, it is possible to ignore the necessity to change social conditions such as poverty and oppression that are also linked to criminal behavior. Moreover, this view may promote the claim by criminals themselves that their “genes” made them do it. While biochemical diagnosis and treatment with medications may be simpler and therefore more appealing than social interventions, this is perhaps reminiscent of the days when frontal lobotomy was the preferred method of biological intervention for aggressive mental patients. In the future, pharmacological solutions to social problems may be viewed as similarly questionable.

Criminality as a specific form of human behavior has been studied by scientists, psychiatrists, psychologists, sociologists, and others who ultimately seek to understand its causes, primarily in the hopes of lessening the occurrence and impact of its more deleterious manifestations. Those researchers who look for solutions in genetics sometimes lose sight of the roles that psychology and environment play in the various expressions of criminal behavior. The same can be said of social scientists who sometimes ignore the roles that genetics and neurochemistry play. It makes better sense to conclude that a combination of genetic, psychological, and environmental influences work in different ways for different individuals leading to the development of criminal behavior in some but not all.

Key terms



metabolic pathway

:

a biochemical process that converts specific chemicals in the body to other, often more useful, chemicals with the help of proteins called enzymes.





neurotransmitter


:

a neurochemical that transmits messages between neurons.





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