The ways serial killers pick their victims may be more deeply entwined with our sexes’ evolutionary history than you’d assume, new research reports.

Knife.

Image credits Pixabay.

Male serial killers tend to treat their victims, who are often strangers, like prey — they “hunt” them, often stalking them before striking. Female serial killers, in contrast, tend to “gather” victims, targeting people they already know, often for financial gain. These are the findings of a new paper which looked into how our evolutionary history plays a part in shaping each gender’s more sinister pursuits and which, the team hopes, can help us catch those that dabble in them.

The wolf changes his coat, not his habits

“If a murder has been committed without a known suspect, you can sometimes use details of the crime to form a profile of what the perpetrator might look like,” said Marissa Harrison, associate professor of psychology at Penn State Harrisburg. “So if you know that men are more likely to commit a crime in a certain way and women are more likely to do it another, hopefully it can help investigators go down the correct path.”

While the public’s, and our editors’ imaginations are rapt with serial killers, Harrison says that very little actual research has been dedicated to understanding them — likely because they’re (thankfully) quite rare. However, while working on a previous study, Harrison noticed a difference between the modus operandi of male and female serial killing — a difference that she was interested in exploring.

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Together with her team, Harrison combed through reputable, reliable news sources like the Associated Press, Reuters, TV networks, and national and local newspapers for data about serial murders in the U.S. In the end, they compiled data on 55 female and 55 male serial killers and set about defining how their approach differed — and understanding why.

Male serial killers, the team found, were almost six times as likely to kill a stranger than their female counterparts. Alternatively, these sinister damsels were nearly twice as likely to kill a person they already knew than male serial killers. Roughly 65.4% of male serial killers stalked their victims, while only 3.6% of female serial killers engaged in this behavior. Harrison believes these differences arise from the roles men and women tended to fulfill in ancient societies, which left their mark on each gender’s psyche.

“Historically, men hunted animals as prey and women gathered nearby resources, like grains and plants, for food,” she says. “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.”

“In our sample, there were two female serial killers who engaged in stalking-like behavior during their crimes. Interestingly, reports indicate that men were also involved in those crimes.”

Surprisingly, there also seems to be a difference in how we perceive each gender of serial killer. The team found that the media and public at large were pretty consistent in the patterns of nicknames they gave to male and female killers.

“Women were more likely to be given nicknames that denote their gender — like Jolly Jane or Tiger Woman,” Harrison adds. “Men were more likely to be given nicknames that suggest the brutality of their crimes, like the Kansas City Slasher.”

Harrison hopes that the findings can help investigators profile killers faster and with more accuracy in the future. She would also like to see the results applied to creating better prevention and treatment programs for violent offenders. However, it is very important for everyone to understand that, while evolutionary psychology may help explain the differences between male and female serial killers, these rules are not set in stone — and must not, in any way, be interpreted as saying that any one person is born to commit crimes.

“Evolution doesn’t mean you’re predetermined to do certain things or act a certain way,” Harrison said. “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.”

The paper “Sex differences in serial killers” has been published in the journal Evolutionary Behavioral Sciences.