Can Biology Make Us Murderers?

"One must feel sorry for those who have strange tastes, but never insult them. Their wrong is Nature's too; they are no more responsible for having come into the world with tendencies unlike ours than are we for being born bandy-legged or well-proportioned". Marquis de Sade (1740-1814), "Dialogue the Fifth" (1795).

If who we are and what we do originates in the brain, than the structure of and the occurrences therein can explain for our entire catalogue of personalities and behaviors. However, what about deviant behavior and personalities? If deviation implies wrong or inaccurate behavior, is there something wrong or inaccurate in the brains of those who are devious? The possibility seems immanent, but also too easy.

Surely there must be something wrong with someone who is extremely violent, or hurts individuals in ways our society will not allow. There are few things more repellent to 'human nature' and morality than the concept of a serial killer. What is different about the brains of these individuals whom our society finds unforgivable and unredeemable predators? Society might find a biological reason for such atrocities more comfortable than the prospects of 'good and evil' or a mistake. This paper will catalogue and attempt to organize the current biological differences between our minds and that of a serial killer.

Can Biology make us Murderers?

Recent reports in science have found discrete locations in the brain that are used in intricate systems that serve as the human moral compass (1).Changes in the brain have long been known to change the behaviors of a man. In the famous example of Phineas Gage, an accident at his job caused an iron rod to pierce through Gage's skull. Gage was able to stand and speak a few moments later. His intelligence was intact, but it soon became clear that this once model young man had been changed by the incident. He now cursed, lied and behaved horribly to people around them. Gage's doctor, John Harlow, said that Gage was no longer Gage, and that the balance "between his intellectual faculty and his animal propensities" had been destroyed. Can this example of brain-injury be used to explain the 'animal propensities' of serial killers?

The concepts of morality and emotion are hard to wed to the notions of science. Neurobiology seeks to find places in the brain where these things exist. However, even neurologists don't necessarily agree upon the dichotomy between 'passion and reason'. The complex interdependence of the things humans think and feel are noticeable to every individual. And this complexity seems to be further proved by the complex organization of the brain. There may seem to be natural dichotomies between thinking and feeling, but perhaps morality is a complex system of inhibition and activation using portions of the brain designated to both. Neurobiology has its work cut out for it, and thus there may be many physical reasons for an individual to be immoral. There may be a simple center that explains all, but more likely there is an intricate system with multiple vulnerabilities.

By finding places in the brain where behavioral traits lie we can understand that there may exist people with neuropathological disorders that can show 'rational-analytic behavior' that is dysfunctional in that it lacks the social emotions that guide normal human behavior. We may find a thinking individual without the portion of his brain that elicits angst or disgust or the fear of social retribution and social acceptance. Indeed, it has been found that the prefrontal cortex, an area of the brain involved in long-term planning and judgment, may not function properly in psychopathic subjects who are said to be 'immoral'. (5) (8) "To know does not necessarily mean to feel, even when you realize that what you know ought to make you feel in a specific way but fails to do so" (3).Ted Bundy 'knew' what he was doing when he brutally murdered his victims, but he may not have been able to 'feel' the moral emotions that such brutality elicits from normal human beings.

Current research indicates that the serial killer has difficulty in actually processing, understanding and using emotional material in general. (6) The material tested varies from emotionally disturbing pictures to simply emotional words. Noting that the right hemisphere of the brain is specialized for processing the emotional significance of words, researchers speculated that "psychopaths, who are unempathic, callous, and emotionally shallow, would rely less than non- psychopaths on right-hemisphere-based decoding strategies." Researchers theorized that psychopaths may rely more on the left hemisphere, which "uses a more verbal-analytic strategy." This was found to be the case and indicates fundamental organizational differences in the brain processes of psychopaths and serial killers. (8)

Neurobiological disorders are alarmingly common among criminals. In one study, 15 death row inmates were chosen for examination. In each inmate, the researchers found evidence of severe head injury and neurological impairment. (2) In many case studies, offenders have been found to have had a history of head trauma and abnormality on Computerised Tomography (CT) scans, Electoencephalography (EEG) scans and neuropsychological testing. (4) Some of the well known serial sexual murderers have had such disorders and injuries. John Gacy had a form of psychomotor epilepsy as a child. Arthur Shawcross, in addition to his psychiatric disorder, had psychomotor seizures related to temporal lobe damage. (2) Williams (1969) reports that habitually aggressive prisoners (like serial killers and psychopaths) have a greater incidence of EEG abnormality (57%) than other prisoners who had perpetrated a single major crime (12%). The EEG abnormality focused on the temporal lobe - an area associated with personality, emotion and behavior. (4)

Biological psychological theories in humans are often strengthened by similar findings in animal research. Behavior models of serial killers can be compared to the kindling phenomenon in animal research. It was found that intermittent electrical stimulation of the brain has the effect of altering brain excitability to the point where repeated stimulation produces seizures. Over a period of time, the brain becomes more and more sensitive to this stimulation, until seizures are kindled spontaneously. In human beings, this model has been applied to explain the escalation of mood disorders over time, particularly manic-depressive disorder. (2) This would mean that repeated stressors may induce an initial minor depression in vulnerable persons. This depression and vulnerability causes the manic-depression to remit. This theory seems to be able to explain the escalating pattern of killings, the relief that some murderers feel after the killing, the quickening of the cycle, and the out-of-control feelings. It may be that some serial killers have an unrecognized, aberrant, or atypical form of mood disorder. One forensic psychiatric expert who examined Ted Bundy made the diagnosis of manic-depressive psychosis and attributed his murders to "uncontrollable manic rage." (2)

The idea of classical conditioning is familiar to psychology. It may be possible for a brain to classically condition itself to enjoy or attribute positive feelings to acts, behavior, or situations that 'normal' individuals would find aversive. (4) One theory is that the psychopathic brain is organized differently as the result of imperfect socialization in the very early years -- arising either from inherited deficits or from a pathological family environment (or both). This could cause attributional differences to occur in the mind of an individual who has been subjected to kindling or other phenomenons.(7) The anatomical basis for a classical conditioning mechanism in the brain of these altered individuals could be the proximity and interconnection of limbic structures linked with feeding and aggression (the amygdala), with structures controlling sexual functions (the hippocampus and septum). (4)

There is also interest in the diencephalic structures of the thalamus and hypothalamus, which have been suggested as having a direct role in aggressive behavior, as well as a role in associating positive or negative emotions with incoming stimuli. Abnormalities in the thalamus might explain a serial killer's inability to maintain personal relationships or display empathy for his victims (Sears, 1991). Also, the thalamus has been associated with pathological activation of fearful and combative behavior (aversive experiences) along with oral and sexual functions (pleasant experiences). When one area is stimulated, arousal may extend to other areas, producing pleasurable feelings associated with violent acts. (4) Perhaps the behaviors that the brain rewards itself for have been altered somehow in the mind of the serial killer. If this is so, than the brain itself attributes positive responses to negative actions. Could this slowly change any one of us into a serial killer as we find that basic pleasure is only achieved through acts denounced by society?

Another interesting finding shows that psychopaths have a greater fear threshold, and are less likely to respond to fear-inducing stimuli. This is not only true for complex situations, but sudden loud noises that would be expected to frighten any individual. It seems that the multiple physiological responses people have to fearful stimuli don't occur as often in psychopaths. Psychopath's heart rate and skin temperatures are low, and their "startle reactions" are substantially less than the average person in these situations. This would mean that psychopaths need more stimulation in order to feel thrills, emotions or intense experiences like you or I. The autonomic nervous system of intensely violent people is intensely sluggish. (5) This is a commonly documented phenomenon in Antisocial Personality Disorder. If a person finds pleasure only in extreme events, perhaps the individual has been denied the pleasures of life that everyone else feels.

Similarly, the hypothalamus plays a role in the reticular activating system, which may block otherwise stimulating activity from reaching the judgement-related cerebral cortex. It has been suggested that such a mechanism may be what is responsible for chronic underarousal in the psychopath, leading to antisocial behavior in an attempt to increase cortical levels of arousal (Bartol, 1980). This seems to be able to explain the thrill-oriented serial killer who increases the frequency of his murders. (4)

There are several other brain related theories that may explain some of the complex behavior characteristics of a serial killer. 5-hydroxyindoleacetic acid (5-HIAA), a metabolic bi-product of the neurotransmitter serotonin, may have an abnormally low concentration in the cerebrospinal fluid of persistently aggressive and anti-social males. If a neurotransmitter plays a role in aggression, than perhaps it can one day unlock a key to the violence of a serial killer. (4) The brain has many ways of regulating aggressive behaviors. It is too early to tell which aspects, functions, chemicals or portions of the brain can cause the difference between a man who gets into fights at bars and another man who murderers several people.

Hormonal factors may also play a role. Androgens, like other hormones, may either have a direct influence on physiological mechanisms governing behavior or organize the developing human brain to make particular behavioral responses more likely. Females exposed to excess androgenic activity show male characteristics such as increased aggression. (4) However, such effects may be due to differential treatment during upbringing. Yet, prenatal exposure to androgens may also cause the same behaviors. All of these differences in chemical makeup could cause or effect other aspects or differences in the serial killer's brain. For instance, the effects of androgens on the organization of the brain could effect the aforementioned tendency for psychopaths to use the left hemisphere of the brain. Using case studies, it is impossible to tell which comes first, the psychotic tendencies, or the abnormalities in the brain.

Serial killer Carl Panzram himself wrote: "All of my family are as the average human beings are. They are honest and hard working people. All except myself. I have been a human-animile ever since I was born. When I was very young at 5 or 6 years of age I was a thief and a lier and a mean despisable one at that. The older I got the meaner I got." German child killer Peter Kurten had drowned two playmates by the tender age of nine. (5) Are the psychopathic criminals really different from birth?

Some of the differences in the brains of these 'monsters' are clearly stated above. Yet, noting these biological differences in the immoral and criminal brain makes punishment and treatment of these individuals a difficult situation. It was suggested that perhaps the 'accountability' of serial killers may be able to be determined by brain-scans once the differences were catalogued. If these differences are detectable, than perhaps we can know who is a serial killer and who is not. However, would this indicate whether the serial killer was born this way rather than having willfully trained himself to enjoy the 'feelings' that his crimes elicit?

Does society have the right to impose the death penalty upon those who are biologically malformed? Biology implies that these individuals suffer from something as simple as a birth defect, or something strange that has happened to or been transcribed in their brains. The 'insanity defense' clearly states that we can not punish a person who does not understand what they have done as being wrong. However, changes or abnormalities in the brain, as exposed above, indicate that serial killers do not understand the world as you or I. As science begins to unravel personality, accountability unravels with it. "The person becomes his parts - some working, some defective through no fault of his own." (1)

Could serial killers simply begin as individuals looking for activities that will allow them to enjoy and take pleasure in life like you or I? Perhaps they've learned that for their 'pursuit of happiness' they must trade in what society imposes upon them as 'morality'. A concept they may not even be capable of understanding.