Criminal Behavior: Nature vs. Nurture Part Two

In Part One of Criminal Behavior: Nature vs. Nurture, we looked at the pertinent environmental factors that may be linked to the causation of criminal behavior. In Part Two we will discover and analyze the flip side of the coin that points more towards biological factors instead of environmental. When searching for information concerning the biological nature of aggression and criminal behavior I found some very interesting research.

The frontal lobe of the brain is the functioning area for behavior in human beings, and there are beliefs in the scientific community that damage to the frontal lobe can cause significant behavioral problems for individuals. In fact, there are findings that prefrontal cortical deficits and abnormalities in the temporal lobe are high within the incarcerated population. (1) Drugs and alcohol are also brought into the discussion as chemicals that poison the brain thus causing changes in a person’s aggressive tendencies. “The most obvious drug that is widely believed to be related to aggression is alcohol. Indeed, in a well known Philadelphia study of homicide, 64% of cases involved alcohol. And in a study of rape, one third of both victims and offenders had been drinking.”(2:129) Neurotransmitters are also important factors in behavior. Excessive levels of dopamine and reduced striatel activity can account for disruptions in motor, cognitive, and emotional ability causing acute schizophrenic psychoses. Aggression itself seems to come about from an interaction between the neurotransmitters dopamine and serotonin. If one or the other is not functioning properly within the brain then abnormal behavior could come about. (3) “Low 5-hydroxytryptamine (serotonin) in the impulsive aggressive individual seems to play a key role, as the recidivistic violent criminal has a low cerebrospinal fluid level of 5-hydroxyindole acetic acid (as do those who attempt or commit suicide).”(1) Age seems to also be important when it comes to genetics/biological factors. The National Institute of Mental Health did a study on child and adolescent violence. “Research suggests that for some youth with early onset behavioral problems, genetic factors strongly influence temperamental predisposition, particularly oppositional temperament, which can affect experiences negatively. When antisocial behavior occurs later in childhood or adolescence, it is suspected that genetic factors contribute less, and such youths tend to engage in delinquent behavior primarily because of peer influences and lapses in parenting.”(4)

Although there is research that supports the sole responsibilities of both genetics/biological and environmental factors of aggression and criminal behavior, research still points toward a more integrated view on this topic. Daniel Weinberger from the National Institute of Mental Health stated that “we will understand at a much more fundamental scientific level the biology of these disorders, how patients are born with dispositions that are much more elaborate than just whether they are passive or aggressive, but very subtlety defined predispositions at the level of neurobiology that make them respond to a variety of environmental circumstances. This will give us the where with all to intervene more judiciously at the biological and environmental side.”(5) Carl Eisdorfer Ph.D, M.D. from Jackson Memorial Medical Center also states that the “theoretical model point of view, I tend to espouse what I call a biopsychosocial model. I think that peoples behavior, feelings, and so on are the bringing together of biologic forces, internal psychological/behavioral forces, and social and cultural settings.”(5)

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