The UC Davis psychology professor’s Bonded by Evolution dispels popular theories about what makes relationships work and why.

How did you end up pursuing this line of research?

I’ve always been fascinated with psychology—but I became interested in studying human attraction and close relationships when I realized that there were two completely different scientific approaches to them. One approach came from evolutionary psychologists, the other from close-relationship researchers, both arriving at different conclusions. It seemed to me that there must be a way in which each approach could inform the other.

There’s a lot in the book about the evoscript—what’s that?

I coined that term as a way of capturing evolutionary psychology’s view of human relationships. It’s rooted in fundamental assumptions that date back to the 1980s and ’90s, when researchers evaluated human mating in terms of Darwinian natural selection. These assumptions are the source of many misunderstandings about successful human relationships. For example, we need to account for the fact that the modern environment—especially with the advent of screen technology—is not parallel to the ancestral environment. Back then social networks were small, and people mated with people they’d probably known all their lives.

You write that the traits humans initially seek in partners don’t predict long-term relationship success. Why?

The concept of mate value—that some people are worth more than others in the mating pool—can be depressing; it tells us that if you’re not smart, super attractive, a good dancer, this will limit your ability to find a happy relationship. This is deeply wrong. Once people come to know each other, they actually stop agreeing about the value of these traits.

What about pair bonding—what does that have to do with human mating?

A number of different species form pair bonds, but most aren’t closely related to us. Humans do because we’re supercharged to put a huge energy investment into rearing offspring, and a pair bond—an emotional attachment that enables parents to work well together—is how nature solved the problem of raising kids. This isn’t restricted to the nuclear family; human attachments can also apply to extended networks of relatives and friends.

You say that compatibility is the major player in successful long-term relationships.

One of the most important revelations of this book is that people can build compatibility—they can, over time, establish good interactive patterns and learn to respond to each other’s needs. Good relationships are wildly idiosyncratic—it’s startling how different people are in different relationships. We also underestimate how people can change depending on the relationship they’re in. Just because you’ve had one unsuccessful relationship doesn’t mean you’re doomed to have another.