“Life is short. Have an affair.” So goes the slogan of the Ashley Madison Agency, host of the online dating site for married persons look for some additional sex on the side. Premarital sex is no longer a moral issue in modern society, but extramarital sex is still considered taboo. So if you were looking for sex outside your marriage, would you tell a potential lover about your marital status? In a recent article in the journal Evolutionary Behavioral Sciences, psychologists Susan Hughes and Marissa Harrison argue that the answer to this question may depend on whether you’re a man or a woman.
The simple fact that there’s a famous dating site specifically for finding extramarital affairs reflects a mystery of human mating that evolutionary psychologists have been struggling to understand for decades. The vast majority of mammal species engage solely in short-term mating. Females selectively breed with the best male they can find, but they expect no help from dad in raising the kiddies.
In contrast, pair-bonding for the purpose of raising children is ubiquitous across human cultures and time periods. Although societies vary in the degree to which they expect couples to remain lifelong monogamous, fathers around the world generally want to play a role in the upbringing of their children. And because it takes human kids so long to grow up, single mothers are always going to be at a disadvantage compared to their partnered sisters.
Thus, long-term monogamous mating seems to be the default reproductive style for humans. And yet, humans also pursue short-term mating opportunities. In addition to the thrill of sexual variety, both men and women gain potential reproductive advantages as well.
For men, extramarital couplings yield the possibility of fathering more children than they could manage with just their wife alone—with bonus points if they can get another man to bear the costs of raising their offspring. For women, sex outside of marriage presents the opportunity to conceive a child with better genes than their husband can provide. These dynamics of extra-pair liaisons are also widely observed in species such as songbirds that also engage in pair-bonding and joint parenting, so this isn’t a uniquely human phenomenon.
Imagine for a moment that you’re married but considering Ashley Madison’s advice. As it comes time to reveal personal information about yourself, should you let your potential paramour know your marital status? Evolutionary psychology makes a prediction about what men and women in this situation are likely to do, as well as their motivation for doing so.
On the one hand, men seeking an affair should keep silent about their marital status. This is because many women will only enter into a sexual relationship if they believe it has long-term potential. That means men will have a greater chance at mating success if they allow women to assume they’re husband material.
On the other hand, women seeking an affair should be open about their marital status. By reassuring their potential lovers that they have no expectations of a long-term relationship, they boost their likelihood of mating success. Doing so also reassures the man that he won’t be held responsible for any child that might ensue from the liaison, since she has a husband back home to take care of that.
To test this this hypothesis, Hughes and Harrison surveyed nearly 600 adults who had either considered or actually had an extramarital affair. The average age of these respondents was 30, so these people were old enough to have grappled with the temptation of infidelity.
Despite the common belief that men are more likely to stray than women, the researchers found no gender difference in either desiring or actually engaging in an extramarital affair. However, they did find a gender difference with regards to the key question in their survey. Specifically, the women indicated that they were more likely to reveal their marital status to a potential lover than were the men. In other words, the results were just as evolutionary psychology would predict.
Hughes and Harrison concede that the decision to reveal marital status to a potential lover is complex, with many factors having an influence. And certainly, there were many men who revealed and many women would did not in this sample. Nevertheless, the researchers also contend that modern humans regularly engage in patterns of behavior that evolved deep in our ancestral past, and these can influence our decisions at an unconscious level.
The data show that both men and women are tempted by infidelity—and even succumb to it—in equal numbers. At the same time, they also show that there are gender differences in the expectations people have as they enter into an extramarital liaison. These distinctions likely reflect the fact that men and women have different goals and concerns in seeking an affair, which no doubt affect many of the decisions they make.
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Hughes, S. M. & Harrison, M. A. (2019). Women reveal, men conceal: Current relationship disclosure when seeking an extrapair partner. Evolutionary Behavioral Sciences, 13, 272-277.