For many, romantic partnerships are at the heart of our well-being in life. Yet, these same relationships can be fraught or hard to maintain. Spouses become bored with each other, grow in different directions, or are no longer sexually satisfied, and they separate or divorce. Infidelity among committed partners is also strikingly common, with somewhere between 20-25% of couples reporting at least one case of a partner straying.
So, why do we still crave these committed, romantic relationships when they can be so fragile? And, how can we make them work better and remain satisfying over time?
To find out, I spoke with evolutionary biologist Justin Garcia, director of the Kinsey Institute and author of the new book, The Intimate Animal. In his book, he explains some of the biological forces acting upon our most intimate relationships and how that affects everything from modern dating to marriage to polyamory, and more. Below is an edited version of our conversation.
Jill Suttie: In your book, you make a case that intimacy is a biological drive, akin to other biological drives, like hunger or sex. But most of us don’t think of it that way. Why do you?
Justin Garcia: By training, I’m an evolutionary biologist and anthropologist, and I think a lot about the role of evolution and selection in shaping who we are. That means thinking about the reality of our being a social primate.
We know we have a desire to engage in sexual activity for reproduction; it’s important for existing into the next generation. And so much of human social life, reproductive life, and sexual activity is couched in terms of long-term bonds. If we think about sexual desire as one lever that selection is acting on for survival and reproduction, then we also have to recognize that long-term bonds—within which a majority of sexual activity occurs for most humans around the globe, historically—had to be selected for, too.
My goal in The Intimate Animal was to really dive into that and take the role of intimacy in relationships seriously. For me, the social and the biological contexts of relationships are one and the same. There’s so much about connection, whether physical or emotional, that is tied into our story as mammals and, particularly, as social primates. Too often we ignore that to our detriment.
JS: There seems to be a widespread view that men and women have different sexual needs. Is that supported by science?
JG: This debate happens in the public sphere, but it’s also one that happens in academic journals. There’s a wonderful argument and series of articles by the feminist psychologist Janet Hyde called the Gender Similarities Hypothesis. Her work shows that many of the psychological sex differences we talk about between men and women aren’t very big. In large samples, something like 5% can be statistically significant, but does it tell us something meaningful about differences between men and women? Not really.
One of the more consistent findings, though, is that men on average have a larger interest in casual sex than women. So, there are some differences around sexual behavior, particularly around sexual desire. But it’s not as large as people think. Similarly, 20 years ago, everyone said that men engage in infidelity more than women. But in newer studies that are asking the questions in more complex ways, we actually see very small gender differences. So, short answer, there are some differences, but men and women are much more similar than we are different.
JS: One of your arguments in the book is that we are biologically wired for monogamous intimacy but not for monogamous sex. What do you mean by that?
JG: When people talk about monogamy, they often mean a monogamous relationship or a monogamous person. In behavioral and evolutionary biology, though, we don’t talk about monogamy as one term. We talk about two elements: social monogamy and sexual monogamy. Part of what I wanted to do in this book was bring that framework to our understanding of humans and relationships.
Social monogamy is a relationship structure, what we call pair-bonding, involving mutual territory defense, nest-building, and raising of offspring. That mutual piece is the key element of a pair-bond that’s different from sexual monogamy or sexual fidelity with one partner. And the reason we separate that is because there are different mechanisms, including in the brain, and different evolutionary pressures shaping them.
In some species, including ours, these are not totally aligned, although often partners attempt to enforce sexual fidelity in social monogamy. But when we look at the genetic parental evidence and make behavioral observations, we see that many animals that form pair-bonds sometimes sexually stray. By separating these pieces out, it gives us a new lens to think about our relationships and the tensions that exist between the safety that comes with deep intimacy and the excitement that comes with sexual variety.
So, say you’re in a long-term bond, where you feel intimacy, you feel connected; but you have this craving for excitement pulling you away from your primary relationship. Sometimes we can bring that tension into our relationship and harness it, instead. In our studies on couples that have long-term passion, they take vacations, have rituals, and do novel things with each other. There are ways we can integrate that into our relationship, to keep a sense of passion and excitement.
Too often, though, we move around like zombies, being pulled by the pressure in our romantic and sexual lives without understanding where it’s coming from and without consciously making decisions. It isn’t only about love, connection, safety, or the quality of a relationship. It’s about these multiple drives that have evolved to serve different functions.
JS: So, these tensions help explain why there is a lot of infidelity in the world. But at the same time, 85% of the world considers adultery immoral. So, is infidelity bad or should we accept it as a consequence of our biology?
JG: I think infidelity is a problem, because it’s a betrayal of a relationship agreement. That can include people who are in open relationships. You can also have infidelity in those contexts, because in polyamory or in sexually open relationships, most people still have a set of rules they’re abiding by. And, those rules can be violated, whether that’s a rule about not having sex with someone in your friend network or always using condoms with someone else.
One of my goals was to explore the tensions, but also let people know they have options that don’t involve betrayal, whether that’s saying a relationship doesn’t work for you and separating, or experimenting with an open relationship, or—instead of letting the desire for spontaneity and novelty pull you away from your primary partner–finding ways we can integrate that into our relationship.
Betrayal almost always causes damage, often for both people—and often to their social networks, as well. When people ask me about infidelity, they often assume it happens because there’s something wrong with their relationship. But in our studies, a lot of infidelity happens for reasons that have nothing to do with whether or not someone loves their primary partner. That doesn’t make it any less painful. But it is a good reminder that sometimes it’s about things outside of your primary connection. When we understand that, we can manage our behaviors and relationships better, I hope.
JS: Polyamory seems like it could be one way to solve that tension. But you argue that many of us are not prepared to enter polyamorous relationships. Can you say more about why not?
JG: Different relationship structures work remarkably well for people, whether it’s being socially and sexually monogamous, in a polyamorous relationship, or single and enjoying singlehood. But we have a tendency to sometimes think that the grass is greener. We may think being poly has all these advantages, and we can romanticize those and forget that, just like in any relationship structure, there are people with high and low satisfaction, people that it works well for and people it doesn’t work well for.
Researchers used to call polyamory “ethical non-monogamy;” then they started calling it “consensual non-monogamy,” because whose “ethics” is it? But consensual is kind of a loaded term, too—are both partners always totally consenting to this? Now, increasingly, researchers are calling it “negotiated non-monogamy” or “disclosed non-monogamy.”
JS: I guess that sort of points to the problem…
JG: Exactly. It points out that often there are asymmetries in the desire for these different relationship structures.
In our studies, we found that about one in five Americans have at some point had some version of a disclosed non-monogamous relationship—whether it’s sexually open, like swinging, or polyamory love. In the case of polyamory, it’s interesting. It’s different than a sexually open relationship in that you’re attempting to manage multiple pair bonds. We find there are some people who do it remarkably well. It really satiates their desire for emotional connection and sexual connection. But, for other people, it’s a challenge to maintain multiple relationships—to balance jealousy, gift giving, quality time with multiple partners, etc.
It’s not that polyamory is good or bad. But, as I wrote about in The Intimate Animal, I’m cautious about the way we imagine different relationship structures to be great without recognizing that they just come with different kinds of effort, negotiations, and compromises.
JS: I’m at an age where many of my friends have young adult children looking for romantic partnerships. But it seems more fraught than it was for us at their age. Why is that? And what advice would you give young adults today?
JG: Dating culture has changed dramatically and in a relatively short period of time. That includes the trajectory of a relationship. Just a few decades ago, for instance, young people would often marry fairly early in their courtship process, and marriage was about starting a grand adventure with someone that you were attracted to and could imagine a future with. Young people today think of marriage as the finale, after you already know everything about someone and have fully investigated them.
We did a study with the Match Group, and we found that about 80% of Gen Z-ers said that they believe they will find true love in their life, but about 45% said they don’t think they’re ready for a relationship—they need to work on themselves first. This highlights that they think being ready is a linear process. If you just go work on yourself, one day you’ll wake up and be ready.
But that’s not how we really show up socially or romantically or sexually. In the best case, your romantic partners are there to help you take risks, explore the world, catch you when you fall. That goes back to the mutual part of all pair bonding, of having a copilot to experience life with. When we put too much emphasis on having to be perfect before being in a relationship, we neglect the fact that relationships are containers within which we can grow and make mistakes and experience the world.
This is a challenge that’s showing up on dating apps and in the offices of matchmakers. Dating apps are a remarkable opportunity to find someone with the same hobbies, kinks, religious background, but it’s more data than the human brain can process. We have an information overload. And that means we’re seeing fewer people interested in second and third dates and getting to know someone. After a first date, they’ll say: “Well, you were wonderful, but you held your fork a little funny during lunch, and I can get back on my app and find someone who doesn’t.”
When the brain has a sense of an unlimited resource, we keep going back to the well to find someone who’s perfect. But if we understand that our brain is playing a dirty trick on us, then we can say, “I found someone I like, and, yes, they did this funny thing with the fork, but I’m going to go on a second date with them anyway, because there’s a whole lot that I liked about them.” We have to grab biology by the horns in those moments and focus more on the deal-makers than the deal-breakers.
JS: Many people believe that what’s hurting them in the dating market is that they’re not attractive enough. What does science say about attraction?
JG: In our Singles in America study, we ask people what they’re looking for in a partner. And what’s been heartwarming for me is that in the last few years, in particular, the number one thing that single men and women are looking for in a romantic partner is someone they can trust and confide in. Yes, people say attraction, humor, sexual confidence, and intelligence are important. But number one for men and women is having someone you can trust and confide in.
I think it’s a powerful reminder; but, it’s also something hard to determine on a first date. Often it takes a little time to really see if you can trust and confide in someone. It also goes back to why infidelity is such a problem. Betrayal corrodes the number one thing so many people want in a relationship, a partner you can trust.
JS: Are there other practical implications of your work you want to share?
JG: I’m not a clinical psychologist or physician, so I’m often cautious about giving advice. I’m in the business of “how come,” not “how to.” But I do think that when we understand more about ourselves, we can change our approach to our romantic and sexual lives.
One way is by having a lot more empathy for ourselves and those around us. Especially in the case of breakups and romantic dissolution, when people ask, “Are you ready for someone else?” or “Why don’t you get back into the dating market?” or “Try to focus on the things you didn’t like about the person.” We wouldn’t say that to someone who was going through bereavement. But, for some reason, people will tell us we can just move on. We all have to recognize the intense grief people go through when they lose a relationship. It’s why we’ve found 50% of people have a yo-yo relationship; they go back after they breakup.
Another thing is when we’re first dating and falling in love, feelings of limerence [infatuation] are a complete mind-body experience, impacting the brain, hormones, heart rate, and how we perceive our beloved’s behavior. This colors our understanding of what’s going on around us and the decisions we make. Are you making risky decisions or thoughtful ones? Are you balancing the intensity of first excitement with long-term intentions?
I believe that the more that we understand ourselves, the better decisions we can make in our intimate life, really prioritizing the role of close connection. These relationships hold the answer to our loneliness epidemic, to our accumulated anxiety about everything—including the environment, politics, the economy, and health. It all comes down to the power of meaningful, intimate social connections.