Photo: Caiaimage/Robert Daly/Getty Images

What are the most important differences between single people and married people? If you asked most people this question, they’d probably answer that single people tend to be a bit lonelier, a bit sadder, maybe a bit more lacking in life purpose and fulfillment compared to their married friends and family members. One would be a lot more likely than the other to be eating delivery pizza alone on a Friday night, that’s for sure.

These are common cultural scripts, at least in the United States, and social science has reinforced them a bit by telling us over and over that getting married does, in fact, bring various benefits to one’s level of happiness and life satisfaction. Marriage is good for you, we hear over and over and over.

And yet: People, on the whole, seem less into marriage than they used to be. At a time when it’s easier than ever before to learn about the purported benefits of getting married, single people are on the rise, and there’s a growing awareness that not everybody gets married by the time they’re 30, or 40, or 50 — that more and more people are building solo lives for themselves that would have been viewed as wildly unorthodox in the fairly recent past. The numbers tell a straightforward story. In 1970, there were 38 million single people in the U.S., and they made up just 28 percent of the population. In 2014, there were 107 million and they comprised 45 percent of the population.

In other words, single people are getting harder and harder to ignore. As Rebecca Traister pointed out in a recent cover story for New York Magazine — adapted from her book on the same subject — there are now so many single women that they alone constitute a potent, growing, and important voting bloc. Add in men and single people are a huge chunk of the population.

For any other group of this size, social scientists would have dug in by now — they would have started figuring out what makes this group tick, what their preferences are, and what sets them apart from the rest of the population (that is, people who are married). But a lot of that basic legwork hasn’t been done yet. “There are studies here and there — people here and there who do something” on single people, Bella DePaulo, a Harvard-trained researcher at the University of California, Santa Barbara, told Science of Us. “But in terms of an actual recognized, established science of single life, we have nothing.”

DePaulo, one of the only public intellectuals whose focus is on single people — she gave a standing-room-only talk on her research at the recent annual convention of the American Psychological Association in Denver — thinks she knows why: Ever since social science has been interested in the concept of marriage, it has endorsed the idea that everyone’s goal and likely trajectory is to get married at some point. “The idea has been that everybody wants to get married, and eventually everybody will, so why bother studying single people?” she said. Single people are either people who have failed to get married, in other words, or married-people-in-waiting. They’re not worth studying as a category unto themselves.

To DePaulo, this is a huge wasted opportunity: A more rigorous attempt to study single people, she believes, could teach us a great deal about what it means to live life according to your own values, about the oft-forgotten pleasures of solitude, about not putting all your eggs into one social and emotional basket. More important, it could dispel some myths and unrealistic expectations about marriage that strain relationships and cause unhappiness.

If only researchers would listen to single people, in other words, they could teach us a lot.

***

Understanding the new science of single people requires grasping two main points: the weaknesses of the extant literature on the (ostensible) connection between marriage and happiness and well-being, and the intriguing nuggets that those few researchers who have dipped a toe into the study of singles have already uncovered.

Back in the early 2000s, DePaulo had taken a one-year fellowship at UCSB (which turned into a permanent post there). Around that time, she decided to write what would become her 2006 book Singled Out: How Singles Are Stereotyped, Stigmatized, and Ignored, and Still Live Happily Ever After, “in part because of my own experience of feeling like I was treated differently because I was single, and then talking to lot of other single people and finding that they have the same experience.”

Like any good researcher, her first step was to review the existing literature on marriage and well-being. “I just assumed that all these claims I had seen so often — get married, you’ll be happier, healthier — I just assumed they were all true,” she said. Her hope for the book, then, wasn’t to dent this consensus, but rather to “find some wrinkle” that would complicate the conversation a little bit. “Maybe it’s not true for older single women, or maybe it’s not true for a certain ethnicity — I was just looking for something like that.”

Instead, she found something much bigger and more shocking. From the very first study she read, she realized that much of the most frequently cited, well-respected research about the effects of marriage were hobbled by potentially game-breaking methodological flaws. Over and over and over, the studies didn’t accurately address the question of the effects of marriage because they looked at groups of people who were currently married, rather than groups of people who had ever been married.

Think about this for a second: If you get married the U.S., statistics suggest that you have about a 40 percent chance of getting divorced at some point (as you might expect, this chance varies based on things like your social class and the age at which you tied the knot). So if you’re looking to honestly answer the question of what marriage “does” to someone, there is no reason to leave out divorced people. But the effects of doing so are clear: Divorce tends to make people less happy, so if you exclude divorcees from your population of married people, that could artificially inflate their reported happiness and well-being. Worse, some studies have lumped in divorced people with single people, artificially deflating that group’s happiness. “I kept thinking, Maybe that’s unrepresentative,” said DePaulo, meaning maybe she was just looking at studies that were bad apples. But no: The bad apples were everywhere, the literature rife with studies that don’t come close to showing what they purported to.

Even studies suffering from these flaws, DePaulo realized, often showed gaps between married and single people that were not that large. And more careful studies and meta-analyses have often shown that there is no clear well-being benefit to getting hitched. A 2012 meta-analysis of 18 studies published in the Journal of Personality and Social Psychology, for example, found evidence that, setting aside some brief, temporary effects, in the long run people who got married did not report being happier or more satisfied in the long term.

So why, despite the serious dearth of research suggesting that marriage brings with it happiness, well-being, and satisfaction, do so many people believe it does? Part of the answer, of course, is that people want it to — there’s some serious confirmation bias at work here. Media coverage hasn’t helped on this front, DePaulo said, and often there has been a gap between what a given paper claims, strictly speaking, and how that claim is translated to a broad audience. “Sometimes, when you read the individual journal articles, the authors will be careful about not making any causal claims,” she explained. “But when they get to the point of making comments to the press or writing review articles, sometimes it ends up being causal. And, on top of that, almost no one does the key comparison of looking at everyone who ever got married and comparing them to people who stayed single.” (Note that the question of causal claims is separate from the question of whether even the correlations discovered in a given paper — people who get married are X more likely than single ones to Y — are accurate, in light of the aforementioned issues.)

Because of what DePaulo sees as a bias to want marriage to be good news, sometimes even small results get overblown in translation. She provided an entertaining example in her APA talk: In 2008, the Washington Post ran a study write-up with the headline “Married Folks Still the Healthiest.” What did the paper actually show? The article doesn’t contain any numbers, but the findings aren’t particularly impressive: 92.9 percent of currently married people rated their health as good or excellent, as compared to 92.6 percent of lifelong single people. That’s 0.3 percentage points.

So on the one hand, there are a bunch of marriage studies that are far less conclusive than they are portrayed to be, and on the other are very few studies about single people — DePaulo said that hardly anyone has tried to “study single life from the perspective of single people.” She mentioned in her slide deck that according to a search of a database of journal articles she conducted, between 2000 and 2015 there were 19,582 academic articles about marriage, and just 501 about people who have always been single. As for articles “motivated by a desire to understand single life,” rather than ones focused on the question of how single people shake off their singlehood? A grand total of 34 published articles, research reports, and book reviews in that 15-year span.

So what has this nascent body of research found? For one thing, it has cast a new light on the question of loneliness. A common cultural script we have about single people is that they are lonely, but researchers are starting to realize that it isn’t quite that simple. In a sample of people who described themselves as “single at heart,” for example, 95 percent said they savored the thought of being alone, while just 5 percent were worried about being alone. One way to assess individual variation here is through the so-called “desire to be alone” scale, and there, research has shown that people who score high are less likely to be neurotic and more likely to be open-minded than people who don’t like alone time. If, as is likely the case, the desire to be alone correlates with being single, this could point to some big, important differences in the personalities of never-married versus married people. There’s also longitudinal research suggesting that never-married single people tend to spend more time with their parents and friends than people who are married. Married people, on the other hand, become more insular after their marriage — there appears to be something of a hunkering-down effect.

So there’s some early evidence, overall, to suggest that lifelong single people, at the population level, differ in certain important ways from those who are married or have been married. But there’s a huge amount of work waiting to be done both to solidify these findings, and to address the countless unanswered questions about how lifelong single people spend their time, what they value, and other ways in which they differ — or don’t — from married people. And a closer examination of these differences might help researchers better identify which sorts of people are likely to benefit either from getting married or staying single.

It’s no wonder, then, that DePaulo hopes that more young scholars dive into this area — there’s a lot of rich terrain to mine. But the most important reason to ramp up such research, she believes, is that the current, prevailing story line about marriage is causing unnecessary harm. “It’s hurting most single and married people,” she said. “It’s hurting single people because they’re led to believe that there’s something wrong with them, something wrong with their lives, even if they recognize at some level that they want to be single. And it also hurts married people, and people who want to be coupled, because if they’re in a bad relationship, they still think If I become single, maybe I’m going to be even more unhappy.”

But it’s tough to chip away at such a cherished belief. There are, after all, still many, many married people in the U.S., as well as millions more hoping to become married, and it’s only human for them to demonstrate a vested interest in the current story line. She sent me a few of the email exchanges she’s had with people unhappy about her work. “Bella, I feel very sorry for you,” wrote one. “Sounds like you have a lot of issues and I’m sure that’s why you are single. No need to respond.”

But in DePaulo’s view, such snarkiness is a small price to pay for the benefits of busting myths about single people, “It’s just ridiculous to think that single life is filled with unfettered trivia or pleasure-seeking,” she said, “or that it’s a life of sadness and bad outcomes.”