A few weeks ago, the two-year old son of Adrian Peterson, star running back for the Minnesota Vikings, was murdered (see here for the CNN article covering this tragic story). Guess who is the most likely culprit when it comes to such unspeakable tragedies? Well, anyone who knows basic principles of evolutionary psychology could probably offer an immediate and likely veridical speculation. In instances when the biological parents are divorced or separated, and the mother has custody of the child, the stepfather or long-term boyfriend is the likely perpetrator. And in the Peterson case, this is exactly what happened.
Let’s step back for a moment to the first paragraph of the preface of my 2007 academic book The Evolutionary Bases of Consumption. Here is what I wrote:
In the preface of her 1997 edited book titled Human Nature, Laura Betzig describes how many of the leading evolutionary psychologists were first exposed to the power of Darwinian theorizing. I have a similar story to tell. In my first semester of doctoral training at Cornell University, I took Advanced Social Psychology taught by Professor Dennis Regan. Unbeknownst to me, one of the assigned readings in that course would profoundly alter my professional career. Roughly halfway through the semester, I read Homicide by Martin Daly and Margo Wilson, wherein they provide a Darwinian account of criminal behavior (e.g., murders and sexual abuse). My epiphany had taken place. Though I was previously aware of Darwin’s theories and had perhaps vaguely heard of sociobiology, I now realized that I had been exposed to a powerful framework for understanding human behavior.
In their classic book, Daly and Wilson demonstrate both theoretically and via painstakingly careful empirical analyses, the evolutionary and biological roots of a wide range of crimes (see here for a recent interview with Martin Daly). For example, irrespective of cultural setting or time period, the most dangerous individual in a woman’s life is her long-term male partner (and not some unknown rapist or lurking serial killer). Suspected or actual infidelity is the number one reason that drives men to aggress if not kill their female partners. Of course, the evolutionary explanation is simple and is rooted in the threats of paternity uncertainty. Of relevance to today’s post, Daly and Wilson showed that the abuse of children is most likely to occur at the hands of a stepparent (the so-called Cinderella Effect). Whenever substantial parental effort is required for the rearing of offspring in a given species, one would expect that organisms would evolve differential parental solicitude (i.e., greater likelihood of investing in kin versus non-kin offspring). Infanticide is an extreme and ugly manifestation of this evolutionary insight.
Incidentally the systematic infanticide of non-kin youngsters has been documented in numerous species perhaps the most infamous of which is when male lions take over a new pride after having chased out or killed the resident male(s), after which they systematically hunt down and kill all of the existing cubs. Incredibly, this gruesome massacre triggers the lionesses to go into estrus. There are numerous human practices that seek to quell threats from rival males in ways that are perhaps less violent albeit quite tragic. As I discuss in my 2011 trade book The Consuming Instinct: What Juicy Burgers, Ferraris, Pornography, and Gift Giving Reveal About Human Nature, the Lost Boys of the Fundamentalist Church of Jesus Christ of Latter Day Saints are young men who are expelled from the group by church elders, as a means of reducing male-based intrasexual rivalry. To the extent that older men view their younger counterparts as a threat to their reproductive fitness, they will come up with “religious” reasons to expel them from the church’s fold. Nature can be brutish.
A few points worth mentioning here:
1) Offering an evolutionary argument to explain why non-kin adults (e.g., stepparents) are more likely to abuse children in their care does not in any way condone or justify the practice.
2) That child abuse is most likely to take place at the hands of stepparents and other non-kin caregivers does not impugn all such individuals. Most stepparents will likely love and certainly not abuse their stepchildren but whenever child abuse does take place, it is extraordinarily more likely to occur at the hands of a non-kin adult.
In the comments section of the CNN article to which I linked earlier, a female reader (Larinna Chandler) posted the following personal insights:
I have an 8 year old with my ex. My hubby and I have two small children. When we first moved in together, I didn’t let him be alone with my son. When he said, ‘You don’t have to pay a sitter, I can watch him’ I said no. I told him matter of fact right to his face that statistically HE would be the one most likely to hurt my baby. That I loved him tremendously, but my kids come first. There were no warning signs, nothing worried me, but the usual statistics. Mom goes to work, leaves young child at home with 20 something boyfriend. Well, I knew he was a good catch when he hugged me and told me he understood, but he would show me all was good. Over time he did. He still didn’t watch my baby for a LONG time though and I can look back and laugh at it now. We have an incredible family. All I knew was I loved that man of mine, I still do...but I love my babies more. When our young son wants to go to my ex’s house and hang out with his older brother...I told my ex the same thing. He rolled his eyes and said that he’d rather I’d be to [sic] paranoid than to not care at all. So...yeah women...Uh...Man up... Kids before a D***.”
Clearly, Ms. Chandler has a well-honed Darwinian-based parental instinct.
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