Thing about evolutionary psychologists is that after giving sciency sounding names to commonplace events, they believe they have discovered something new. Happens with wild abandon in the peer-reviewed paper “The mate switching hypothesis” by David Buss and others in Personality and Individual Differences. (The title of today’s post was lifted from one of the many popular media summaries.)

First thing Buss does, after quoting Kinsey on infidelity rates as if these numbers were reliable, was to give a name New & Improved! name to infidelity: “mate-switching.”

Although breakups are often moralized as “failures,” we propose that selection has sculpted a complex psychology designed to jettison current mates and acquire new ones in circumstances wherein mate switching would have been historically evolutionarily advantageous.

And so Buss moralizes infidelities as “advantageous”. Now this theory as Buss states it, as all experience proves, is immediately false. We all know plenty of couples, even infertile ones, who stuck together even when this “strategy” was not “evolutionarily advantageous”. This “mate-switching” therefore cannot be universal.

Of course, we also know some couples who haven’t stuck. Who has more kids, incidentally, women who stick or those who wander? (The paper focuses on women.) Are the rates you’re thinking of current? Were they the same, say, 150 years ago? In England? In Sumatra? Kenya? Philippines? Across all time?

Here’s the “mate-switching hypothesis”:

Humans have adaptations to (1) monitor their current mating relationships for benefits received and anticipated and costs incurred and anticipated, (2) evaluate alternative potential mates while already mated, (3) circumvent a partner’s mate guarding tactics, (4) engage in extra-pair infidelity (from flirting to serious affairs) as a tactic for assessing and courting alternative desirable and interested partners, (5) deploy exit strategies for breaking up a current partner in ways that minimize costs, (6) and switch to a new partner when cost/benefit calculations render circumstances propitious for switching.

Now this makes women sound like baby-optimizing machines, does it not? If that’s so, answer me this: which women are more likely to use contraception and kill their unwanted, those women who stick or those who wander? And if mankind has adaptions to boost gene rates as Buss suggests, why is there so much contraception, abortion, and adoption?

Buss makes it appear that all people constantly engage in these “adaptive” algorithms, they having little choice in the matter because the “adaptive” behaviors are programmed (in some sense) in their genes. “Evolution drove me to cheat: I didn’t want to, but my genes talked me into it.” How then do we explain the great number of faithful people who end up having lots of kids and the women mate-switchers who don’t?

Nothing in life comes with a guarantee. From an ancestral woman’s perspective, hazards from the environment, other species, and importantly, other humans, could render her mate debilitated or dead. A bite from a poisonous snake, an incapacitating disease, or an attack from a warring group could decrease her partner’s mate value.

You don’t say?

The final decision about whether or not to implement a mate switching strategy, as illustrated by the discussion above, is neither easy nor straightforward. Foremost, it requires a suite of assessment adaptations—monitoring the current partner’s mate value; tracking one’s own mate value; monitoring the desirability and interest of alternative potential mates; assessing the current partner’s investment in, and commitment to, the relationship; and tracking self, partner, and potential partner changes in mate value and anticipated future mate value trajectories. Information from these assessment adaptations feed into the decision to implement a mate switch, which if positive, requires tactics for breaking up and emotionally detaching—aspects that Boutwell and colleagues (2015) call primary and secondary mate ejection.

Zero recognition from Buss that humans are unlike all other animals. No recognition that love, justice, religion, knowledge of the good, logic, evil, and so on are used by people in deciding whether to stick or skate. Desiring to maximize a genetic future, in the sense that people are thinking, “If I dump Bob, statistics promise I’ll have 1.4 more kids with Kevin” doesn’t happen. It’s more like, “John promised to spend a lot of money on me. Goodbye, Bob.”

Do women (or men) ever leave because they think they’ll have more kids? Sure. Do most leave for that reason? Hardly. And reason they do. Buss must be committed to the idea that when a woman bolts for more money, she may think she’s doing it for the money but that’s just her brain tricking her into a situation where she’ll have more kids.

The rest of the paper is the same: “Another output of mate switching psychology is emotional disengagement, a process of psychologically divesting from the current partner.” I don’t have space to criticize things like “Woman’s mate preferences shift to more bodily masculine and behaviorally dominant men when ovulating”, results which rely on (typical) bad statistics but which have a grain of truth.