The Science of Love and Sex

After her divorce, New York Times health columnist Tara Parker-Pope scoured the available research on coupling — zoology, evolutionary psychology, clinical studies — to determine the formula for enduring love. She shares her findings in the new book For Better: The Science of a Good Marriage, a clearheaded, stats-driven look at which qualities comprise lasting love. The book is meant for couples wondering if they'll make it to their golden anniversary, but it should be required reading for anyone looking to up her odds on happily ever after.

MC: Let's cut to the chase — what do we write in our online profile to ensure a good match?

TP: It's not what you write, but what he writes. According to studies, for low divorce risk, you're looking for someone over 25, who finished college — because if he dropped out, he'll quit other things, too — and who grew up with both parents, or one parent in a long subsequent marriage — especially if you didn't. When the wife is a child of divorce, the couple's chances of divorce go up 59 percent; when both partners' parents are divorced, your odds jump 189 percent.

MC: Is there really such a thing as a chemical connection?

TP: Yes. One famous study discovered that a woman uses scent to choose a mate, sniffing for a set of genes called MHC that complements her own, to give her offspring the best chance of survival. That also means that any woman on hormonal contraception, like the Pill, can't accurately find her MHC complement because her biological instincts are blunted. So if you're making a long-term relationship decision, you might want to use an alternative birth control for at least six months. Because when you make the wrong MHC call, you're not only more likely to be unhappy in your marriage, you're also more likely to cheat.

MC: Does chemistry really have such a hold on us?

TP: It seems to. When women are ovulating, they instinctively dress more provocatively. And when you fall in love, you are literally high on dopamine. So here's where our instincts can fail us: You may regret any decisions made during the first rush of romance because you're basically experiencing a major mental health crisis.

MC: How can we be sure we'll match up sexually in the long term?

TP: You could date by demographic. The General Social Survey, conducted by the University of Chicago every two years, has found that rich and poor people have more sex than middle-class people; Jews and agnostics have more sex than Christians; the politically active have more sex than those who are apolitical, though extreme liberals have more sex than extreme conservatives. And smokers and drinkers have more sex than those who abstain from these other quote-unquote vices.

MC: Any easy ways to rule out a guy?

TP: Beware the boyfriend you never fight with. One study followed newlyweds over a three-year period, and many who fought a lot in the beginning were happier after three years, while those who avoided conflict were headed for divorce. And it may seem obvious, but if a guy ever rolls his eyes at you, even when accompanied by nice words or laughter, that is bad news. It's a spontaneous physical expression of contempt, a big predictor of divorce.

MC: Why do we fall for jerks like that?

TP: MRI studies show that the chemical storm of infatuation is strikingly similar to drug addiction and obsessive-compulsive disorder. That said, though biology drives us, experience shapes us. Tolerating a bad guy for a long time probably says more about your family background or past relationships than your biology.

MC: And what if our standards are just too high?

TP: That's a good thing! New research out of the University of North Carolina contradicts your mother's theory that marriages fail because expectations are too high. In fact, they tend to be met by a marriage — so if yours are low, you'll have a marriage without good communication, romance, or passion. If they're high, there's an excellent chance you and your mate will live up to them, and hopefully live happily ever after.