part of the lesser ape family, the gibbon. As humans are the most social of all the primates, except for perhaps the bonobos, it is unwise to assume we’d naturally be monogamous. Body dimorphism (different sizes for different genders) is correlated with male competition for mates. If men and women were monogamous, we’d be the same size, as the gibbons are. If we were completely polygynous (men taking multiple female partners), men would be twice the size of women, as male gorillas and orangutans are. Chimps, bonobos, and human males are all around 10 to 20 percent larger and heavier than females, which implies we have similar rates of promiscuity.
The Biology of Fidelity—Vasopressin and Prairie Voles
The well-studied monogamous prairie voles maintain a single pair bond while raising several litters. As in humans, sex triggers oxytocin release in the females and vasopressin release in the males. The meadow voles, on the other hand, are solitary, asocial, and promiscuous. The vasopressin receptor is quite different in this species. When genes from the monogamous male prairie voles were injected into the brains of the promiscuous male meadow voles, more vasopressin receptors were formed, and the animals started to fixate on and mate with one female vole only.
Vasopressin in the males peaks during sexual arousal. It not only triggers partner preference but is also involved in male parental care. I know what you’re thinking: Can I inject vasopressin into my husband? No, and some guys have more vasopressin than others. There are different genes that code for vasopressin, and some men have certain genes that others don’t have. Men who have a gene variant called 334 score lower on feelings of attachment for their spouses and are more likely to have experienced a marital crisis during the past year or to be in a relationship without being married.
Testosterone levels not only affect sex drive and sexual response but also have a lot to do with fidelity and parenting impulses. Married men and fathers have lower testosterone levels than single and childless men. Right after his child is born, a man’s testosterone levels might fall as much as 30 percent. Men who maintain multiple female partners (polygyny) have higher testosterone levels than monogamously married men. Not surprisingly, married men with higher testosterone levels have sex more frequently than those with lower levels, and men who cheat have higher testosterone levels than those who don’t. Unconsciously, women may know this. In one study, women rated men with lower voices (more testosterone) as being more likely to be unfaithful and were more likely to select more masculine men with lower voices as short-term, rather than long-term, partners.
The Coolidge Effect
Named for Silent Cal, the story goes that he and the missus were separately being shown around a farm. Upon hearing that the rooster mated dozens of times a day, Mrs. Coolidge said to the guide, “Tell that to my husband.” Later, when he heard his wife’s remark, the president asked, “With the same hen?” “Nope. It’s a different hen every time.” “Tell that to my wife.”
The Coolidge effect, that varying the sex partner invigorates the libido, has been documented in many male mammals, including humans. But it turns out that female primates are aroused by novelty as well. Unfamiliar males are more attractive than the known quantity. “The search for the unfamiliar is documented as a female preference more often than is any other characteristic.” Nature has bred philandering into our genes, enhancing the mating strategy of more copulations in order to increase the likelihood of passing those genes on. If guys who are players make more babies, there will be more players in the gene pool.
Ever wonder why men who seem to have it all—fame, fortune, and a loving family—throw it all away for a bit of strange? It’s nature, trumping both reason and willpower. Novelty is the strongest attractor. Many of us are “novelty seeking.” We enjoy new restaurants, new music, new friends, and new hobbies. Research suggests that people who cheat are not only novelty seekers but also more likely to be extroverts than their partners are. They’re also simply more easily bored.
The Space Between
Couples who spend all their time together may end up being too close. Like a fire deprived of oxygen, sexual energy sputters when there’s no room to breathe. You each need to bring something separate and “other” to the partnership, which means you have to go out there and have your own experiences. Girls’ night out is good for both of you. Don’t confuse love with merging. Eroticism requires separateness; there must be a synapse to cross.
Typically one partner will be clingier while the other will be squirming away. Some people comfort themselves in a dyad, while others soothe themselves solo. Compromise is key here, as we all have our sweet spot regarding intimacy. Some of us want to share everything and be bound at the hip, while others of us would like a little elbow room, please.
Part of the problem is that we’ve been fed this idea that our spouse should be able to provide everything we need: love, security, companionship, and hot sex. But the intimacy and comfort of a committed relationship carry a completely different energy (not to mention brain chemistry) than eroticism and lust do. Some of the hottest sex you’ve ever had probably occurred with someone you didn’t know all that well, right? The excitement of two people coming together rests on the uncertainty of where it’s going and whether it will last. Once you’re committed to each other, that spark is history. The trick is to balance the need for unpredictability and novelty with the need for consistency and reliability. And it’s no easy trick.
Our sex may be less hot unless we each “get a life,” but there’s a competing theory about spending time together for the good of the partnership. Couples who spend weekly time talking or being active together are more likely to be happy than couples who take less time to bond. Spouses who share friends spend more time together and have better marriages. Since the 1970s, we’re spending less time with our partners (from thirty-five to twenty-six hours a week) and more time doing other things outside the home, mostly work. For couples with kids, the number of hours spent together has gone from thirteen to nine.
Our emotional needs may be clamoring for more time together, while our animal, lusting selves may require time apart for a sense of novelty. Balancing our needs for intimacy and isolation is challenging and a frequent source of stress in our relationships. The first step is to honestly appraise what your needs and desires are and then to lovingly communicate them to your partner. You can’t negotiate what isn’t on the table, so you’re going to have to show your hand in order to win. There is one-way autoregulation, which is “I can do this for myself” or “You can do this for me.” Then there’s two-way mutual regulation: “We do this for each other.” If two people heal the relationship actively, the relationship will heal the two people. Pour your attention into the space between and it will nurture you in return.
Surviving an Affair
Nearly a third of marriages survive an infidelity.
