There’s a strange whiff in the media air, a sort of polyamory chic in which liberally minded journalists, an aggregate mass of antireligious pundits, and even scientists themselves have begun encouraging readers and viewers to use evolutionary theory to revisit and revise their sexual attitudes and, more importantly, their behaviors in ways that fit their animal libidos more happily.

Much of this discussion is being fueled by Christopher Ryan and Cacilda Jethá’s scintillating new book Sex at Dawn , which explores how our modern, God-ridden, puritanical society conflicts with our species’ evolutionary design, a tension making us pathologically ashamed of sex. There are of course many important caveats, but the basic logic is that, because human beings are not naturally monogamous but rather have been explicitly designed by natural selection to seek out ‘extra-pair copulatory partners’—having sex with someone other than your partner or spouse for the replicating sake of one’s mindless genes—then suppressing these deep mammalian instincts is futile and, worse, is an inevitable death knell for an otherwise honest and healthy relationship.

Intellectually, I can get on board with this. If you believe, as I do, that we live in a natural rather than a supernatural world, then there is no inherent, divinely inspired reason to be sexually exclusive to one’s partner. If you and your partner want to screw your neighbors on Wednesday nights after tacos, participate in beachside orgies lit by bonfire, or pull on your eyeless, kidskin discipline helmet and be led along by bridle and bit down the road to your local bondage society’s weekly sex fest, then by all means do so (and take pictures). But the amoralistic beauty of Darwinian thinking is that it does not—or at least, should not and cannot—prescribe any social behavior, sexual or otherwise, as being the “right” thing to do. Right is irrelevant. There is only what works and what doesn’t work, within context, in biologically adaptive terms. And so even though any good and proper citizen is an evolutionarily informed sexual libertarian, Darwin provides no more insight into a moral reality than, say, Dr. Laura Schlessinger.

(On a related tangent, why do we look for moral guidance about human sexuality in the rest of the animal kingdom, a logical fallacy in which what is “natural”—such as homosexual behavior in other species—is regarded as “acceptable”? As if the fact that bonobos, desert toads, and emus have occasional same-sex liaisons has any moral bearing whatsoever on gay rights in human beings—even if we were the lone queer species in this godless galaxy, even if it were entirely a “choice” between two consenting adults, why would that make it more reasonable to discriminate against people in homosexual relationships?)

Beyond these philosophical problems with seeking out social prescriptions from a nature that is completely mute as to what we should do with our penises and vaginas, however, there’s an even bigger hurdle to taking polyamory chic beyond the tabloids, talk shows, and message boards and into standard bedroom practice. And that is simply the fact that we’ve evolved to empathize with other people’s suffering, including the suffering of the people we’d betray by putting our affable genitals to their evolved promiscuous use.

Heartbreak is every bit as much a psychological adaptation as is the compulsion to have sex with those other than our partners, and it throws a monster of a monkey wrench into the evolutionists’ otherwise practical polyamory. It’s indeed natural for people—especially men—to seek sexual variety. My partner once likened this to having the same old meal over and over again, for years on end; eventually you’re going to get some serious cravings for a different dish. But I reminded him that people aren’t the equivalent of a plate of spaghetti. Unfortunately, we have feelings.

Unless you have the unfortunate luck of being coupled with a psychopath, or have the good fortune of being one yourself, broken hearts are not easily experienced at either end, nor are they easily mended by reason or waved off by all the evolutionary logic in the world. And because we’re designed by nature to be not only moderately promiscuous but also to become selfish when that natural promiscuity rears its head—again, naturally—in our partners, “reasonable people” are far from immune to getting hurt by their partner’s open and agreed-upon sex with other parties. Monogamy may not be natural, but neither is indifference to our partners’ sex lives or tolerance for polyamory. In fact, for many people, especially those naively taking guidance from evolutionary theorists without thinking deeply enough about these issues, polyamory can lead to devastating effects.

One of the better evolutionary-based accounts of the human heartbreak experience is a 2006 summary by Rutgers University anthropologist Helen Fisher. Drawing largely from work by psychiatrists, Fisher surmises that there are two main stages associated with a dead and dying romantic relationship, which is of course often preceded by a partner’s infidelities. During the “protest” stage that occurs in the immediate aftermath of rejection:  

Abandoned lovers are generally dedicated to winning their sweetheart back. They obsessively dissect the relationship, trying to establish what went wrong; and they doggedly strategize about how to rekindle the romance. Disappointed lovers often make dramatic, humiliating, or even dangerous entrances into a beloved’s home or place of work, then storm out, only to return and plead anew. They visit mutual haunts and shared friends. And they phone, e-mail and write letters, pleading, accusing and/or trying to seduce their abandoner.

At the neurobiological level, the protest stage is characterized by unusually heightened, even frantic activity of dopamine and norepinephrine receptors in the brain, which has the effect of pronounced alertness similar to what is found in young animals abandoned by their mothers. This impassioned protest stage—if it proves unsuccessful in re-establishing the romantic relationship—slowly disintegrates into the second stage of heartbreak, what Fisher refers to as “resignation/despair”: 

With time the spurned individual gives up pursuit of the abandoning partner. Then he or she must deal with intensified feelings of helplessness, resignation and despair. Drugged by sorrow, most cry, lie in bed, stare into space, drink too much, or hole up and watch TV. Feelings of protest and anger resurface intermittently, but rejected lovers mostly just feel profound melancholy … Some people in the despair phase of rejection kill themselves. Some die of a broken heart. Broken-hearted lovers expire from heart attacks or strokes caused by their depression … As the abandoned partner realizes that [reunion] will never come, dopamine-making cells in the midbrain decrease their activity [causing] lethargy, despondency and depression.

It’s depressing to even read about, I know, but for most people, those all-important chemicals eventually begin pulsating again when a new love affair begins. Let me note, however, that one of the more fascinating things about the resignation/despair stage, and one that Fisher doesn’t really touch on, is the possibility that it actually serves an adaptive signalling function that may help salvage the doomed relationship, especially for an empathetic species such as our own. As I mentioned earlier, heartbreak is not easily experienced at either end, and when your actions have produced such a sad and lamentable reaction in another person, when you watch someone you care about (but no longer feel any real long-term or sexual desire to be with) suffer in such ways, it can be difficult to fully extricate yourself from a withered romance. If I had to guess—and this is just a hunch, in the absence of any studies that I’m aware of to support this claim—I’d say that a considerable amount of genes have replicated in our species solely because, with our damnable social cognitive abilities, we just don’t have the heart to break other people’s hearts.

In any event, we may not be a sexually exclusive species, but we do form deep romantic attachments, and the emotional scaffolding on which these attachments are built is extraordinarily sensitive to our partners’ sexual indiscretions. I also say this as a gay man who, according to mainstream evolutionary thinking, shouldn’t be terribly concerned about his partner having sex with strangers. After all, it isn’t as though he’s going to get pregnant and cuckold me into raising another man’s offspring. But if you’d explained that to me as I was screaming invectives at one of my partners following my discovery that he was cheating on me, curled up in the fetal position in the corner of my kitchen and rocking myself into self-pitying oblivion, or as I was vomiting my guts out over the toilet for much of the next two weeks, I would have nodded in rational Darwinian ascension while still trembling like a wounded animal.

Jealousy in homosexual couples is an interesting thing. One of the most frequently cited findings in evolutionary psychology is the fact that men tend to become more jealous when their female partners have sex with other men, whereas women are more jealous when their male partners show signs of “emotional infidelity” with other women. This makes good sense from an evolutionary perspective, because prior to the era of DNA testing, men were extremely vulnerable to being cuckolded and investing their limited resources in some other guys’ genes (conveniently packaged in the form of children), whereas women, who evolved to rely on their male partner to help them raise their offspring to reproductive age, were at risk of having his attention—and hence his resources—diverted to another woman and her kids.

So when it comes to homosexual affairs, writes Northern Illinois University psychologist Brad Sagarin and his colleagues in a 2003 report in Evolution & Human Behavior , “a same-sex infidelity does not entail the asymmetrical threats of mistaken paternity and of resources being diverted to another woman’s children, suggesting both that the sexes may be similar in their jealous responses and that such responses may be less intense than in the case of opposite-sex infidelities.” In fact, in studies designed to test this basic hypothesis, the researchers indeed found that jealousy was less intense when straight participants were asked how they would feel, hypothetically, if their partners had a homosexual fling than if they were to become involved with someone from the opposite sex. Personally, I think the participants would have other things to worry about besides jealousy if their partners were on the down-low, but these data do clearly show that reproductive-related concerns indeed moderate jealousy feelings in human romantic relationships.

But bisexuality aside, as any gay person with a past knows, homosexual relationships certainly aren’t without their fair share of jealousy. Although as a general rule gay men are indeed less distressed by sexual infidelity than are straight men, there are meaningful individual differences in this regard—and, I’m willing to go out on a limb and say this, most of us gay men certainly aren’t completely okay with the idea of our partners having sex with whomever they please, nor are most lesbians comfortable with their partners committing emotional infidelity with other women. Now perhaps I’m in a minority in caring so much about my partner’s same-sex behaviors—at least, the ones not including me. Dan Savage, for example, said recently that [gay men] are “not psycho like straight people are about [sexual infidelity in their partners].” But I’m not so sure. Often we’re just as psycho. In my case, when back then I informed the sexual interloper that I would gladly emasculate him with a crisp pair of scissors if ever he made contact again with my long-term partner, this was classically aggressive “mate-guarding” behavior as seen in straight men threatening their sexual rivals.

So to me, and because fatal sexually transmitted infections for which gay men are unusually vulnerable, such as HIV, were not present in the ancestral past and could not have produced any special adaptive psychological defenses, sexual jealousy in gay men can only be explained by some sort of pseudo-heterosexuality mindset simulating straight men’s hypervigilance to being cuckolded by their female partners. All this is to say that I reacted the way I did because, at an unconscious level, I didn’t want my testiculared partner getting impregnated by another man. I don’t consciously think of him as a woman, mind you; in fact, if I did, I assure you I wouldn’t be with him. But tell that to my gonads and amygdalae. I would imagine the same is largely true for lesbian relationships; at an unconscious level, a lesbian’s bonding with another woman may trigger concerns in her partner about her “male” spouse’s disinvestment in real or prospective offspring.

And that’s this once-heartbroken gay evolutionary psychologist’s musings for the day.



In this column presented by Scientific American Mind magazine, research psychologist Jesse Bering of Queen's University Belfast ponders some of the more obscure aspects of everyday human behavior. Sign up for the RSS feed, visit, friend Dr. Bering on Facebook or follow @JesseBering on Twitter and never miss an installment again. For articles published prior to September 29, 2009, click here: older Bering in Mind columns. Jesse's first book, The Belief Instinct (Norton) [The God Instinct (Nicholas Brealey) in the U.K.], will be published early February, 2011.

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