Making Sense of Biology
Nothing in Biology Makes Sense Except in the Light of Evolution, Theodosius Dobzhansky. (1973). The American Biology Teacher, 35(3), 125-129.
“The great King of Kings
Hath in the tables of his law commanded
That thou shalt do no murder”
Shakespeare, Richard III, 1, 4.
In this installment, I tackle a topic associated with a typically October theme, Halloween. John Carpenter’s classic: Halloween (1978) begins with the murder of 17 year old Judith Meyers by her 6 year old younger brother Michael. Fifteen years later Michael escapes and begins a murder spree in the small town of Haddonfield, Illinois. In various sequels of Halloween we eventually learn that Michael Meyers is not truly human, but that his murderous desires and abilities are associated with supernatural evil.
Myers, as a mythical figure, does not truly conform to his real world inspiration, the serial killer. Neither does the media’s depiction of real serial killers conform to their actual behavior. Elliot Leyton writes that the modern serial killer assumes the mantle once worn by “monsters, demons, ghouls, vampires, werewolves, and zombies1.” Leyton contrasts the romantic notion of fictional characters such as Dr. Hannibal Lecter, who is portrayed as intelligent, glamorous, cultivated, physically powerful, and sexually gifted with that of the reality of serial/multiple killers who are generally without intellectual and physical attainments. Indeed what we know of psychotic killers indicates that they may be mentally incapable of developing planned killings (as portrayed by Thomas Harris in his Hannibal Lecter character.) Zdzilaw Marchwicki, who became known as the “Vampire of Silesia” killed some 14 women in 1960’s Poland. His victims were unknown to him and “targets of opportunity.” The lack of connection to his victims explained why he was difficult to catch. It had nothing to do with any superior intelligence or planning. He was eventually captured when he confessed after being brought in for a domestic violence charge2.
So what do we know about multiple or serial killers? First, the answer to that question depends on how you define multiple or serial killer. For example, while we may find contract murderers or state bureaucrats who engage in multiple murders reprehensible, they don’t really fall into the Michael Myers, Jack the Ripper, or Ted Bundy archetype. The Halloween notion is of the murderer who kills for murder’s sake. In the real world, multiple/serial killers cannot come back for sequel after sequel. Thus their modus operandi can be distinguished between those who decide to kill many people all at once; with no hope of survival themselves (e.g. Eric Harris and Dylan Klebold) or serial murders as the Vampire of Silesia who would have kept killing women if he had never been in a position to confess. Despite these differences in “motivation” evolutionary theory may provide us with important insights into these behaviors.
Homicides are rare and the homicides of the sort I wish discuss are even rarer. In 2002, the rate of homicide in the United States was 5.6 per 100,000 persons3. The vast majority of these murders are associated with social and cultural factors, e.g. crime, poverty. However, even in these categories there is evidence of evolutionary factors at play, such as the gender disparity.
|Sex of Victim||Male Offender||Female Offender|
Thus most people murdered are male, but they are murdered mainly by other males (4328/4931 = 0.87) and of the females murdered, most of them are murdered by males (1778/1980 = 0.90.) Buss discusses this gender disparity in the light of two potential hypotheses: “the slip-up hypothesis” and the “homicide module hypothesis4.” In both of these scenarios, murder is an “adaptive strategy” that might be utilized in specific circumstances. These explanations may do more to explain more about killing in general (whether it is that which is legal or illegal) than they do to explain the serial or multiple killer. Despite this fact, the gender disparity holds up within the confines of the serial murderer as well.
Serial killer murders probably make up no more than 1% of all murders. A specific sort of murder that may fall into the category associated with serial killers is sexual homicide. This is estimated at about 1% and 4% prevalence amongst all murders in the United States and Canada respectively5. Sexual homicides may provide us with useful information to explain serial murders in general (realizing that not all serial murderers engage in sexual homicide.) The evidence suggests that sexual murderers often fall into the behavioral category known as psychopathy. Psychopaths are mainly male, and show callous, manipulative, superficial, and violent interpersonal style6. One study has shown that sexual homicide offenders have elevated levels of psychopathic traits relative to other offenders. In addition, these offenders show an even greater level of violence and sadism in the commission of these crimes. The level of sadism and violence exhibited indicates that they are deriving both sexual and general pleasure during the commission of these acts7.
If some serial killers are psychopaths, then how do evolutionary mechanisms explain their existence? Also what of the serial/multiple killers that do not fall into this category? There are several views of psychopathy. Some suggest that the psychopath is just an extreme version of “normal” behavior. Under this hypothesis, these individuals appear, solely by chance. Another hypothesis is that psychopathic behavior is an adaptive strategy. This view holds that the psychopath is engaging in an “r-selection” and cheater type strategy that will increase their reproduction, often at the expense of society at large. Clearly by this model, the psychopathic player strategy can only be effective to increase fitness if these players remain at low frequency. This notion suffers from a number of difficulties. Not the least of which is that this strategy guarantees that the genes that engender it will always be rare. Under this scenario such genes can easily be lost in populations due to genetic drift. There is also the problem that the r- and K-selection hypothesis has been demonstrated not to be a legitimate dichotomy, especially in humans8. Finally, some theories suggest that psychopaths result from failures in brain modules that were selected for adaptive reasons, such as theory of mind and superconsciousness. Theory of mind involves the ability of humans to comprehend and feel the state of mind of other humans. This was thought to be a requirement of increased social living and complexity of modern humans. One of the largest evidences of the existence of theory of mind was the recent discovery of mirror neurons. These actually allow our brains to conceive of and feel the states of other persons, without actually performing the task in question ourselves9. Studies have shown that in some aspects of theory of mind abilities that psychopaths underperform, while in others they are no different from non-psychopathic individuals. It is argued that these results are not fatal to the theory of mind explanation, especially if psychopaths are capable of “understanding” the emotions of others, but not actually feeling them in a way that prevents their manipulative actions. In other words, this ability may actually help them be even more effective as “cheaters” in society.
My colleague, Michael Rose advances the idea that psychopaths (or sociopaths) result from a failure of another sort of brain module (superconsciousness.) Superconsciousness when properly functioning allows individuals to calculate that costs of their behaviors relative to their individual fitness in various social circumstances. Again, since all complex traits are influenced by genetic variation, some individuals inherit defective modules. He suggests that since psychopathy can be produced by brain injuries or disease and that these occur in specific portions of the brain, that therefore this behavior results from poor functioning (as opposed to being an adaptive strategy10.) This observation is also consistent with the fact that other developmental and personality disorders can produce individuals who are serial murderers (e.g. schizophrenia, as in the case of David Berkowitz, Son of Sam11.)
Finally, what of the serial or multiple killers that seem to not be suffering from any diagnosable mental illness? Leyton discusses these in his Hunting Humans. Leyton suggests that the modern American multiple killer is not suffering insanity or delusions. The vast majority of these individuals are of European American descent and from the working or lower middle class. They display an incredible class-consciousness and a need to punish society for their inability to move up its social ladder. In his model, Ted Bundy murdered the very upper middle class women that he coveted, but was unable to have. His acts were designed to wreak vengeance on that sector of society for denying him his rightful status. However, Leyton fails to realize that the “need” that males have to achieve social status is something that is well embraced by evolutionary theory. If indeed, our mate preferences are evolved and these preferences operate through our various behavioral mechanisms, any male that does not fall into the preferred category could potentially exhibit pathological behavior. Indeed, this could explain why much of the violence in human societies occurs both to maintain the social hierarchy of some males over others, and by those who are subordinated to break out of their social oppression.
Indeed, while this month’s theme is the reality of the serial and multiple murderer, such individuals have little influence on the character of human society. It is precisely their rarity that captures our attention and makes them the stuff of our nightmares. If we really think about our social dynamics, and its impacts on life and death, we should be far more concerned about those highly functional people whose impacts on others are homicidal. While we should be wary of the Gacy’s, Berkowitz’s, and Marchwicki’s amongst us, they will never kill as many in their careers, as our social inequalities do to the innocent each day. Is this what our King of King’s really meant when he commanded: “Do no murder?”
Notes and References
- Leyton, E., Hunting Humans: The Rise of the Modern Multiple Murderer, (New York, NY: Carroll and Graft Publishers), 2001.
- Ibid, pp. 43 – 53.
- U.S. Dept. of Justice, Federal Bureau of Investigation, Crime in the United States 2002: Uniform Crime Reports (Washington, DD: U.S. Government Printing Office.)
- Buss, D.M., Evolutionary Psychology: The New Science of Mind, (Boston, MA: Allyn and Bacon), 1999.
- Roberts, J.V. and Grossman, M.G, Sexual homicide in Canada: A descriptive analysis, Annals of Sex Research, 6: 5-25, 1993.
- Kinner, S., Psychopathy as an adaptation: Implications for Society and Social Policy, in Bloom, R.W. and Dess, N, editors: Evolutionary Psychology and Violence: A Primer for Policymakers and Public Policy Advocates, (Westport, CN: Praeger Publishers), 2003.
- Porter, S. et al, Characteristics of sexual homicides committed by psychopathic and nonpsychopathic offenders, Law and Human Behavior 27(5): 459-470, 2003.
- Brune, M. and Brune-Cohrs, U, Theory of Mind—evolution, ontogeny, brain mechanisms, and psychopathology, Neuroscience and Behavioral Reviews 30: 437-455, 2006.
- Graves, J.L., What a tangled web he weaves: Race, reproductive strategies, and Rushton’s life history theory, Anthropological Theory,2(2): 131-154, 2002.
10. Rose, M.R., personnel communication, 2008.
11. Firth, C.D., The Cognitive Neuropsychology of Schizophrenia, (Hove, UK: Lawrence Erlbaum), 1992.