In the interest of full disclosure, I spent the first twenty-eight years of my life (give or take) being utterly baffled by the opposite sex (in the interest of radical honesty, I turned 28 this past December). Despite the inordinately perplexing nature of human courtship, research across academic fields has managed to cast some illuminating rays on this quite murky subject. The really interesting questions in this area are painfully obvious, both to the academic and the layperson: 1) what do women find attractive, 2) what do men find attractive, 3) what are the secrets to a long lasting relationship, 4) why do some relationships go sour, 5) how do men and women select their mates, and so on. I could expand this list for pages—as could most readers—but I want to pause and consider the last question in a bit more detail. How is it that from amongst throngs of possible suitors, humans pick a mate? Let’s be honest, who hasn’t pondered this very question at least at some point in their life (eHarmony, anyone)?
My colleagues and I study the origins of particularly egregious types of human behavior. Crime, aggression, and violence are daily topics that we consider when conducting our research. Why then would a scholar of crime be interested in human mating, one might ask? The answer, my friends, is simple. Permit me a minute, however, to wade through some minutia in order to get us to that destination. There is now overwhelming evidence concerning the importance of genetic factors for human behavior (Turkheimer, 2000) including antisocial behavior. Now, does this mean that our genes are like some “ghost in the machine” (to borrow Pinker’s  phrase) run amok—pulling little levers in our brain and making us behave in certain ways? A promising movie plot for the summer blockbuster season, perhaps, but not quite how it works. In reality, genes exert influence, but they do so by increasing probabilities of certain outcomes—not by making them happen—at least when we are talking about something like behavioral outcomes.
Okay, one hurdle crossed: genes matter for behavior. A second point to consider, now, is that a long line of criminological research suggests that crime runs in families (Frisell et al., 2011). What does that mean? It means, quite frankly, that a small number of families in the population account for a lot of criminal activity (Frisell et al., 2011). So how would mate selection play into all of this. Well, consider a rather interesting possibility; what if humans select mates based on certain criteria? Shocking, I know, I’m suggesting that you didn’t pick your partner at random (did anyone really think it worked that way?). Okay, here’s where it gets truly intriguing. What if—just what if—part of the selection criteria that humans use when selecting mates is to pick a romantic partner who behaves in similar ways? If true, what might that mean for some of the more antisocial members of the population?
A recent project conducted by myself, Kevin Beaver of Florida State University and J.C. Barnes of the University of Texas at Dallas addressed this very question (Boutwell et al., 2012). We compared mating couples on several outcomes ranging from minor drinking and smoking behaviors all the way to self-reported arrests. Remarkably, the couples in our sample were quite similar, “more alike than different” (to borrow from our title) for a litany of antisocial outcomes. Now, the astute among you might cry out at this point; wait! What if couples who have been together a long time simply started to resemble each other with the passage of years. Great point! We attempted to investigate this issue and while we couldn’t do it perfectly, our results suggested that the similarity was already in place for these couples, regardless of how long they had been together.
So let’s bring this all home, shall we? Our results suggested that mating couples are similar for various measures of antisocial behavior. Okay, so what does that mean for intergenerational research on crime? Well, if you recall, genetic influences are important for criminal behavior. Next, crime runs in families. So, if individuals select mating partners based (in part, but not in the whole) on overt forms of antisocial behavior then maybe the genes that increase the odds of aberrant behavior are being concentrated in certain families. Could this help to explain the intergenerational transmission of crime within families? Certainly, it won’t tell the whole story, but it surely might play a role. As with all scientific research, however, we are obliged to put in the caveat that our results are in need of replication. One should never place too much stock in a single study. We should point out, though, that ours was far from the first study in this area (Krueger et al., 1998). Evidence continues to accumulate regarding the role that behavior plays in human mate selection, an area of scholarship known as assortative mating research. We anxiously await these future studies.
In the meantime, let us return to the initial premise of this article. Human mating is fascinating, and thankfully (primarily for this author), it is an outcome that we can investigate empirically. In other words, we don’t have to simply rely on our best guess about human courtship and reproduction. I would direct interested readers in this area to the exceedingly thorough and broad body of work conducted by psychologist David Buss. Few others, in the form of articles and books, have done more to shed light on the intricacies of human mating. In closing though, I’ll leave you with a thought. Human mating is not a haphazard endeavor. If you are in a romantic relationship stop and consider what these findings might mean. Perhaps it might cast a new light on the nature of your relationship. On second thought, understanding ones mate, in anything other than a cursory way, might just be a very pleasant pipedream. We have just started a new year though and, as always, hope springs eternal in this regard.
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Boutwell, B.B., Beaver, K.M., & Barnes, J.C. (2012). More alike than different: Assortative mating and antisocial propensity in adulthood. Criminal Justice and Behavior, 39, 1240- 1254.
Frisell, T., Lichtenstein, P., & Langstrom, N. (2011). Violent Crime Runs in Families: A Total Population Study of 12.5 Million Individuals. Psychological Medicine 41:97–105.
Krueger, R.F., Moffitt, T.E., Caspi, A., Bleske, A., Silva, P.A. (2006). Assortative mating for antisocial behavior: Developmental and methodological implications. Behavior Genetics 28: 173-186.
Pinker, Steven. 2002. The Blank Slate: The Modern Denial of Human Nature. New York, NY: Penguin Group Inc.
Turkheimer, E. (2000). Three laws of behavior genetics and what they mean. Current Directions
in Psychological Science, 9, 160–164.
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