Most men are excited by the idea of their wives or girlfriends being with other men. Yes, most. They may or may not actually like it. But many a man finds himself aroused upon seeing his lady flirt with a stranger, or perhaps a friend. He may be jealous, even very angry. Still, he can’t help but want to make love to her as soon as they get home, his erection stronger than usual, and his ejaculation more powerful, as if he is pumped up to win some sort of sexual competition with the other male for the prize of this valuable female, his wife.  

A more adventurous gentleman might even encourage his lady to have sex with the other man, or dress in “slutty” clothing when they go out in the presence of other men, or at least talk about the fantasy of being with another man, perhaps while pleasuring her with a dildo, which *represents* the other man. 

Traditionally, this kind of husband is called a cuckold, an old English word that carries connotations of unwilling sexual submission and humiliation. Many cuckolds, willing or not, are sexual submissives in their relationships, helpless slaves to their women’s desire for other men, or their own fetish for being cuckolded by their “slutty” wives. 

But most people have never even heard of a “cuckold.” And most gentlemen who enjoy watching or imagining their female primemates having sex with other men in threesomes , at swing parties, in porn or with dildos, don’t feel humiliated at all. They do feel extremely excited, and experience harder erections and stronger ejaculations than usual. 

What’s going on here? There are many explanations, but one of the more compelling reasons for this type of male arousal lies in human evolutionary biology. 

Until recently, biologists thought that there was only one kind of sperm in semen with a single goal: to swim to the egg and inseminate it. It was assumed that the ejaculatory release of sperm was like the proverbial gunshot before the big race that has all the little tadpoles swimming directly to the egg. Recently, evolutionary biologists Robin Baker and Mark Bellis found that these “egg-inseminators” make up only about one per cent of a man’s sperm count. So what about the rest of the tadpoles? It seems that most sperm behave less like a bunch of individual marathon racers than a football team, with some players playing offense and others on defense. They discovered that many sperm don’t swim to the egg at all, but clearly hunt and kill sperm from another man that might also be in the vagina into which they and their brothers have spurted. These killer sperm actually contain *weaponry* that destroy the *enemy* in a Sperm War. Or, using football terms, they are the offense, tackles and fullbacks in the Super Bowl of Sex going on inside the woman. Other sperm on a man’s *team* play defense, blocking and protecting their inseminator-quarterback brothers from other men’s warrior sperm. 

Why Sperm Wars? How did this genetic football game come about? Scientists speculate that, like our cousins, the bonobos and common chimps, our human ancestors were not monogamous, and often several males would mate with one fertile female within a few days of one another. These different men’s sperm would then intermingle within the one woman, duking it out for the evolutionary reward of fertilizing her egg. 

Sperm Warfare explains men’s passion for football and other war games, as well as male excitement over female nonmonogamy 

Whenever a gentleman gets ready to have sex with a lady, he unconsciously considers the odds of her being with another man. If he feels she is totally faithful to him, he might be happy about that, but his erection won’t be at its strongest, nor will his sperm count be at its highest. Unconsciously, his testicles *know* they don’t have to fight an adversary, so they need not generate the full army (or football team) of several hundred million sperm. Therefore, he *conserves* semen. After all, he only needs to send in a few sperm to reach an egg where he has no rivals. 

But if he feels he could be a cuckold, if he sees his lady having sex, or if he just feels that she could—whether he likes the idea or not—his testicles spring into action and produce as many hundred million warrior sperm, blockers and inseminators as they can. The result is that the man has a much stronger erection, more copious ejaculate and a more intensely pleasurable orgasm than he routinely does. 

A happy cuckold gives his hot wife a pedicure as she chats with another man 

Apparently, the human male is wired to be aroused by sexual competition. This is one reason why so many men are drawn to so-called “slutty” women, despite how society attempts to denigrate sluts. 

This also explains why so many men love porn. When a man watches porn, he tends to watch a woman he desires having sex with someone else, usually another man, or maybe even with several men, as in the popular gangbang genre of porn. Some male porn lovers enjoy watching women masturbating or lesbian porn, but the vast majority of men choose to watch heterosexual porn, meaning they are watch another man with a slutty woman, triggering a stiff Sperms Wars-powered erection. 

The Sperm Wars theory also explains why so many men, even if they adore their wives, get sexually bored with them. If a gentleman feels there is no possibility that he could be “cuckolded,” and that his wife could be with another man, his sperm count will stay *comfortably* low. 

This is not to say that couples can’t stay monogamous and enjoy hot sex for many decades. But a marriage that never even entertains the possibility of cuckoldry, ie., another man having sex with the wife, is doomed to low sperm counts and comfortable boredom in the bedroom. 

A hint of rivalry excites the male, makes him feel that his woman is worth fighting for. Of course, the danger is that jealousy, even “retroactive jealousy” over past lovers or “fantasy jealousy” over future lovers, might overwhelm a man to the point that the Sperm Wars going on within his balls only adds fuel to his rage and paranoia. Thus, a lady must respect her gentleman’s boundaries; with some men, playing the Sperm Wars game is playing with fire. 

But remember: the woman doesn’t actually have to have sex with the other man to create the scintillating Sperm Wars effect. It is only necessary that her primemate think she might, even if he just imagines it, and even if everyone knows it’s *just* a fantasy. Indeed, for most couples, the power of Sperm Wars and the experience of being “cuckolded” are best and most safely explored in the realm of the imagination. 

Now, if only we could keep the wars to the sperm, and stop the wars between people… 

~Susan M Block, Ph.D.