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Humans are unusual among mammal species in their strong tendency to engage in long-term sexual relationships. Most mammal dads are deadbeats — contributing their bit of sperm to the reproductive process, but having nothing to do with mom or the kids after that.

Among humans, however, is the norm — a man and a woman (usually, but not always) fall in love and commit to their relationship for the sake of raising a family. Given the cost in terms of time and resources needed to raise human children, it makes sense that we would have evolved to adopt a long-term strategy. In other words, it seems to be human nature to be monogamous.

And yet, humans quite frequently engage in short-term sexual relationships as well. Even in societies where extramarital affairs are severely punished, the temptation to cheat can be too overpowering to resist. Moreover, those of us who remain committed to our spouses still feel the urge to try out other partners. If it were truly human nature to be monogamous, we wouldn’t be tempted to stray.

Evolutionary psychologists resolve this paradox by proposing that men and women employ both long-term and short-term mating strategies, depending on the circumstances. It’s important to note that the common belief that men prefer short-term sexual relationships while women prefer long-term ones is not part of this theory, nor is it borne out by the data. Women who have children need help raising them, and having a man around who is biologically related to those kiddies — and thus committed to their welfare — is important. Likewise, most men reckon they’ll get more sex in a stable relationship than if they play the field, so they stick around.

Only a minority of men have what it takes to successfully play the short-term mating game over the long haul, and those who do have little incentive to commit to a single woman. Players who also feel social pressure to settle down rarely stick to their wedding vows, as attested to by the countless scandals of Hollywood celebrities. In a similar vein, women who are committed to their careers may decide they don’t want the distraction of . But they still have sexual needs, which they meet on the short-term mating market.

Over the course of our lives, most of us employ a mixed strategy of short-term and long-term mating. As young adults, we often pursue exploratory short-term relationships until we find someone to commit to. And if that long-term relationship goes sour, we once again start exploring other options. This was probably the typical pattern of our hunter-gatherer ancestors, who formed monogamous pairings for the purpose of raising a child but weren’t necessarily committed for life. In fact, the notion of lifelong marriage as the standard for sexual relationships didn’t come around until we started engaging in agriculture around 10,000 years ago when people had to think about who would inherit their property.

lays out human reproductive practices as a two-pronged strategy, a mixture of short-term and long-term mating. But as Australian psychologist Evita March and her colleagues point out, these sexual styles aren’t two separate categories. Rather, they represent two ends of a continuum ranging from the shortest of all, the one-night stand, to the longest, namely lifelong monogamy. One example is the friends-with-benefits relationship, which is certainly long term and involves some level of emotional , but without the commitment of monogamy. Another example, the focus of March’s study, is the booty call.

In a booty-call relationship, a couple meets on repeated occasions specifically for the purpose of having sex. An encounter is initiated when one of them calls or texts the other requesting a meeting. The expression “Netflix and chill?” has become a catchphrase for a booty-call request. The booty-call relationship differs from friends with benefits, in that FWBs also socialize with each other and enjoy each other’s company even in non-sexual situations. A booty-call relationship, in contrast, is strictly sexual, with little or no emotional attachment.

Booty-call relationships share features with both short- and long-term mating strategies. Like short-term relationships, the focus is on sex to the exclusion of any social or emotional component. But unlike one-night stands, booty calls involve repeated encounters with the same partner. So the ultimate question that March and colleagues asked was whether men and women view booty-call relationships as short-term or long-term affairs.

To explore the nature of booty calls vis-à-vis long- and short-term relationships, March and colleagues asked over 500 people in their 20s to respond to an online questionnaire. About half of the respondents were college students, while the rest were in the workforce. Likewise, about half of the men and women reported having experience with a booty-call relationship. The respondents were asked to report on personal characteristics they’d consider necessary to be willing to engage in one of the three relationship types — long-term, short-term, and booty call.

In addition to gathering demographic information about the respondents, the researchers asked them to rate the desired level of the partner’s physical , kindness, and social level. Ideally, we all want our sex partners to be attractive, kind, and wealthy, but in the real world, we have to make trade-offs. To enforce similar constraints in the survey, the respondents were allotted a set number of “mating dollars,” which they had to distribute among the three traits. The researchers interpreted a large allocation of mating dollars to a trait as indicating a necessity and a small allocation a luxury — something that’s preferred, but not a deal-breaker if it’s missing.

For short-term mates, both men and women rated physical attractiveness as a necessity, but they saw kindness and social level as luxuries. This finding is consistent with plenty of other research on short-term relationships, which are strictly sexual in nature with no other social or emotional component.

For long-term mates, men still considered physical attractiveness a necessity, but women saw it as a luxury. Both men and women rated kindness as a necessity and social level as a luxury. These results don’t completely to previous findings, which typically show men prizing attractiveness most and women valuing social level over looks. This may reflect changes in society, as many women today are financially independent and don’t need their mate to be the bread-winner for the family.

When it came to booty calls, both men and women rated the attractiveness of the partner as a necessity, suggesting that they viewed these as more like short-term than long-term relationships. However, women — but not men — rated kindness as necessary, implying that women see booty calls as somewhat similar to more committed relationships. This supports the notion that booty calls are, at least for women, a sort of exploratory sexual affair that has the potential of developing into a long-term relationship.

The men, in contrast, seem to consider booty calls as a series of one-night stands with little thought toward the possibility of deeper commitment. Furthermore, respondents who reported experience with a booty-call affair were asked whether it had developed into a more committed relationship. The women were more likely to report that it had, whereas the men were more likely to say it had not.

This contradictory finding is perhaps due to a reporting in which each respondent answered according to his or her desired outcome rather than the actuality. At any rate, the data from this study suggest that women view booty-call relationships as more committed than their male partners do. March and colleagues conclude that the booty call may be a compromise between short- and long-term mating strategies, but this is mainly a compromise only for women.

In my opinion, consenting adults should be free to pursue whatever sexual activities they want to. But I also think they need to keep their eyes wide open to what they’re getting themselves into. When it comes to sex, open communication about expectations is essential if couples want to maximize the benefits of the relationship without getting burned in the long run.