Why Are Most Serial Killers Men?

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Serial killing is not a recent occurrence, nor is it confined solely to the United States. Throughout history, spanning back to ancient times, individuals who commit serial murders have been a global subject of articles. During the 19th century in Europe, Dr. Richard von Krafft-Ebing conducted early documented investigations into violent sexual offenders and their criminal acts.

Although serial murder is a relatively uncommon incident, estimated to constitute less than 1% of all annual homicides, there exists an intense curiosity about the topic that surpasses its actual prevalence. This fascination has resulted in a multitude of articles, literary works, and cinematic productions. The origins of this widespread intrigue can be traced back to the late 1800s, when a series of unresolved murders involving prostitutes occurred in London’s Whitechapel district. A mysterious individual who identified himself as “Jack the Ripper” purportedly corresponded with the police, taking credit for these killings.

Hollywood’s entertainment sector has significantly influenced how the general public views serial murder. Plotlines are deliberately tailored to amplify public engagement rather than provide an accurate representation of serial killings. The public becomes captivated by the perpetrators and their heinous deeds, often described as the work of “unstable” criminals. This contributes to the existing bewilderment surrounding the true dynamics of serial murder. Furthermore, there is a prevailing misconception that serial killers are predominantly men. Is this a reflection of reality? What are the underlying reasons behind the apparent male predominance among serial killers?

Why Are Most Serial Killers Men?

In 1998, a highly respected former FBI profiler made a statement indicating that there were no instances of female serial killers. As mentioned previously, media outlets and entertainment platforms also contribute to the perpetuation of stereotypes, often portraying all serial wrongdoers as men and dismissing the possibility of women participating in such heinous acts of violence.

When literature or films depict acts of violence and murder committed by women, they frequently portray the woman as a manipulated victim under the control of a dominant male figure. This prevalent yet stereotypical portrayal in the media aligns with societal gender myths that suggest men possess inherent aggressiveness while women exhibit passivity. In actuality, both aggression and passivity can be acquired through socialization and are not exclusive to any gender.

Contrary to expectations, the truth about the gender distribution of serial killers diverges significantly from the prevailing myth. Despite the historical predominance of male serial killers, documented crime data reveals the existence of female serial killers.

In the United States, the FBI reports that approximately 17% of all serial homicides are attributed to women, which is notably higher than the 10% of total murders committed by women. According to this statistic, women commit more serial killings than other types of murder in terms of their overall involvement in homicides. This fact challenges the conventional beliefs surrounding serial murders.

Certain scholars contend that the relatively “subtle” methods employed by women, such as poison, and their ability to manipulate others into carrying out their acts could potentially elucidate why there is a higher proportion of male serial killers apprehended, while female perpetrators manage to evade capture.

What Differentiates Men and Women in the World of Crime?

Gary Leon Ridgway, the Green River killer
Gary Leon Ridgway, the Green River killer, pleaded guilty and was sentenced in 2011 for his 49th killing, of Becky Marrero, who vanished after leaving a SeaTac motel in 1982. Image: Mike Siegel / The Seattle Times, 2011.

An unsettling study conducted in 2019 delved into the behaviors of 55 male serial killers and 55 female serial killers who carried out their murderous acts in the United States between 1856 and 2009. The aim was to discern the distinctive factors that set apart male and female serial killers and shed light on the reasons why men appear to be more prone to adopting this gruesome and violent pattern.

In particular, scholars employed the mass media approach to collect research data. They scrupulously examined reliable and respected sources like the Associated Press, Reuters, television networks, and national and local newspapers to amass information about serial killings.

According to the researchers, male and female serial killers exhibit different preferences in the victims they choose and how they carry out their crimes, which may be the result of millennia of psychological development from our ancestors, who predominately lived as hunter-gatherers for about 95% of human history.

The researchers posit that male serial killers lean towards “hunting” their victims, frequently targeting strangers. Conversely, female serial killers lean towards “gathering” victims, often focusing on acquaintances or individuals they are already familiar with, often for financial motives.

Marissa Harrison, Associate Professor of Psychology at Penn State Harrisburg and lead author of the study, explains in a statement:

Historically, men hunted animals as prey and women gathered nearby resources, like grains and plants, for food. As an evolutionary psychologist, I wondered if something left over from these old roles could be affecting how male and female serial killers choose their victims.

Marissa Harrison, Associate Professor of Psychology at Penn State Harrisburg.

Upon scrutinizing the collected data, the researchers uncovered that male serial killers were nearly six times more inclined to murder strangers, while female serial killers were nearly twice as prone to killing individuals they had pre-existing familiarity with. Moreover, 65.4% of male serial killers engaged in stalking behavior towards their victims, in contrast to 3.6% of female serial killers.

Media Focused On Serial Killers

Robert Berdella, “The Kansas City Butcher.”
Robert Berdella, “The Kansas City Butcher.” Image: Tribune News Service.

As researchers collected data from various media outlets, they also observed a distinction in how the media portrayed serial killers, particularly evident in the nicknames attributed to them.

Moreover, despite significant public interest in serial killers, there has been limited research on these crimes, perhaps because serial killers have become relatively rare, unlike the period of the 1970s to 2000s in the United States. The excessive sensationalism surrounding some of them influences our objectivity.

Harrison makes an observation, stating that women were more prone to being labeled with nicknames that highlighted their gender, such as ‘Jolly Jane‘ or ‘Tiger Woman.’ Conversely, men were more inclined to be given nicknames that underscored the brutality of their actions, like the ‘Kansas City Butcher.

Harrison’s aspiration is that the discoveries, aside from assisting investigators in solving crimes, could contribute to the development of programs aimed at preventing and treating violent offenders. Furthermore, she underscores that while evolutionary psychology can shed light on disparities between male and female serial killers, it does not imply that individuals are inherently predisposed to commit crimes.

Evolution doesn’t mean you’re predetermined to do certain things or act a certain way. It means that it may be possible to make predictions about behavior based on our evolutionary past. In this case, I do believe that these behaviors are reminiscent of sex-specific behaviors or assignments in the ancestral environment. And perhaps we can understand this better through an evolutionary lens.

Marissa Harrison, Associate Professor of Psychology at Penn State Harrisburg.

Is a Pattern of Violence Caused by Hormones Possible?

Aileen Wuornos is shown in this undated photograph from the Florida Department of Corrections. Wournos was executed by lethal injection October 9, 2002 in Florida for murdering six men when she was a prostitute.
Aileen Wuornos is shown in this undated photograph from the Florida Department of Corrections. Wournos was executed by lethal injection October 9, 2002 in Florida for murdering six men when she was a prostitute.

Broadly speaking, the predominant motivating factor behind male serial murderers tends to be rooted in sexual desire. This doesn’t imply that every male serial killer perpetrates sexual violence against their victims. But at some level, there is usually a sexual element, even if it’s purely psychological. The urge to take other people’s lives often drives serial killers to commit murder. It’s worth noting, as previously mentioned, that the specific identity of their victims often holds less significance.

Most men, of course, go through life without killing anyone. Nonetheless, a combination of male biology and social upbringing seems to render men more predisposed to acts of violence. This tendency is observable across a wide array of cultures worldwide.

To unravel this phenomenon, it becomes essential to delve into the context of evolution once again. Over countless millennia of development, males have historically reaped rewards for their aggressive behaviors. A propensity for violence is apparent even among chimpanzees, the closest living relatives to humans. For males, engaging in violence can have implications for their social standing. Biologically speaking, a lack of status might translate to missed opportunities for mating.

In fact, sexual frustration frequently emerges as a recurring motif among serial killers. Gender-based disparities could potentially have a biological basis: fluctuations in a gene called MAOA, coupled with early-life stressors like abuse or substance use, can elevate the likelihood of criminal conduct in males. Moreover, men are more inclined than women to anchor their ethical choices in abstract principles rather than empathy.

The cycle of violence is a phenomenon that fosters delinquency, violence, and aggression, as shown in a 2013 study that highlighted the risk that childhood maltreatment and neglect pose to all children. Other elements, such as psychopathy, impulsivity, and disruptions in the hypothalamic-pituitary-adrenal (HPA) axis, contribute to the manifestation of aggressive behaviors.

Furthermore, a study published in 2014 proposed that these extreme manifestations of violence may arise from a deeply intricate interplay of biological, psychological, and sociological factors. It was also suggested that a considerable proportion of serial killers might have grappled with neurodevelopmental disorders, including autism spectrum disorders or head injuries.

Cruelty to Animals Is a Hallmark of Serial Killers

Jeffrey Dahmer flanked by his attorneys during a preliminary hearing in Milwaukee, Wisconsin, August 22, 1991.
Jeffrey Dahmer flanked by his attorneys during a preliminary hearing in Milwaukee, Wisconsin, August 22, 1991.

In 2003, researchers undertook the task of addressing these gaps by delving into the histories of serial murderers, exemplified by the Dahmer series. This series delves extensively into the killer’s early life, starting with the second episode. The researchers meticulously examined five case studies of serial killers using the framework of social learning theory. Through their investigation, they unveiled a clear connection between acts of cruelty towards animals during childhood and the emergence of aggressive tendencies towards humans during adulthood. Furthermore, the patterns of aggression displayed towards animals in childhood often mirrored those directed at humans in later life.

An article by the Animal Rights, Ethics, and Science Foundation echoes this same conclusion. The article highlights that, as far back as the 1960s, a number of studies established a strong correlation between acts of violence inflicted upon animals and subsequent violence directed towards humans. This link was particularly evident within the United States. Among these studies, nine of them demonstrated a noticeable association in children between engaging in animal abuse and later becoming both perpetrators and victims of bullying and violence, both within school environments and familial contexts.

In the United States, the mistreatment of animals is a criminal offense across all states, warranting swift responses and legal interventions. Adding to this, in 2014, the FBI made a significant move by reclassifying this offense as a Class A felony. It becomes increasingly evident that these acts of cruelty serve as indicators, shedding light on potential domestic violence and other criminal propensities. Furthermore, they offer insights into the psychological makeup of individuals, opening avenues for preventing future crimes by channeling initial offenders towards appropriate social support services.

The origin of such violent tendencies might provide an explanation for the overrepresentation of men on the roster of serial killers. Multiple studies underscore the lack of empathy or a disturbing indifference to animal welfare observed in certain men. Notably, Professor Harold Herzog’s research at the University of Western Carolina disclosed that “Among adults charged with animal cruelty, men vastly outnumber women across most types of abuse.”

In the end, constructing a definitive profile of a serial killer remains elusive. Although men appear to exhibit a higher susceptibility to descending into the abyss of serial murders, there is no standard mold that fits all cases. Similar to various other facets of human psychology, there exist variations in personality and subtle behavioral nuances that consistently challenge preconceptions and popular notions propagated by the media.

While it might be convenient to decode a sort of “secret cipher” to swiftly identify offenders, reality disappoints such expectations. The key lies in remaining vigilant about common traits like animal cruelty and behavioral disorders, representing the sole available strategy for early detection of individuals at potential risk.