Photo: Detail of work by Gail Albert Halaban/Courtesy of Robert Mann Gallery. The creation of these photographs was funded in part by the Design Trust for Public Space.

Until I was 37 years old, I lived alone. It never struck me as particularly odd. If you’ve been in New York for any length of time, you know from both intuition and daily observation that many people live on their own in this town. But I never fully appreciated how many—and by extension, how colossally banal my own solitary arrangement was—until I checked with the Department of City Planning a couple of months ago. How many apartments in Manhattan would you have guessed have just one occupant? One of every eight? Every four? Every three?

The number’s one of every two. Of all 3,141 counties in the United States, New York County is the unrivaled leader in single-individual households, at 50.6 percent. More than three-quarters of the people in them are below the age of 65. Fifty-seven percent are female. In Brooklyn, the overall number is considerably lower, at 29.5 percent, and Queens is 26.1. But on the whole, in New York City, one in three homes contains a single dweller, just one lone man or woman who flips on the coffeemaker in the morning and switches off the lights at night.

These numbers should tell an unambiguous story. They should confirm the common belief about our city, which is that New York is an isolating, coldhearted sort of place. Mark Twain called it “a splendid desert—a domed and steepled solitude, where the stranger is lonely in the midst of a million of his race.” (This from a man who settled in Hartford, Connecticut.) In J. D. Salinger’s 1952 short story “De Daumier-Smith’s Blue Period,” the main character observes that wishing to be alone “is the one New York prayer that rarely gets lost or delayed in channels, and in no time at all, everything I touched turned to solid loneliness.” Modern movies and art are filled with lonesome New York characters, some so familiar they’ve become their own shorthand: Travis Bickle (in Taxi Driver, calling himself “God’s lonely man”); the forlorn patrons in Nighthawks (inspired, Edward Hopper said, “by a restaurant on New York’s Greenwich Avenue”); Ratso Rizzo (“I gotta get outta here, gotta get outta here,” he kept muttering in Midnight Cowboy … and died before he could). Remember Miranda in Sex and the City, racing off to the ER from panic attacks over dying alone? And then there was Christina Copeman. She famously did die alone in her apartment in East Flatbush. Her skeletal remains were discovered around Christmastime last year, an estimated twelve to eighteen months after she’d died, still neatly dressed in a beret and overcoat.

It’s stories like Copeman’s—terrifying in their every particular and, more important, real—that catch the attention of social scientists and have led some to the same conclusions as Mark Twain. “Every 20 or 30 years, we have a lament about the decline of community, and it’s usually due to cities and urbanization,” says Robert Sampson, the criminologist who chairs Harvard’s sociology department, when I visit him one sunny morning this fall. He mentions one of the classics of the genre, Louis Wirth’s Urbanism As a Way of Life. “It’s all about the impersonal way of life in the city—how it almost deranged people, led to this sort of schizoid personality, to psychosis and loneliness.” He smiles. “It’s a fun piece, actually. There’s some great quotes in it.” He leans back in his chair. “But this idea that cities are bastions of lonely, despairing people is a myth,” he says.

In American lore, the small town is the archetypal community, a state of grace from which city dwellers have fallen (thus capitulating to all sorts of political ills like, say, socialism). Even among die-hard New Yorkers, those who could hardly imagine a life anywhere else, you’ll find people who secretly harbor nostalgia for the small village they’ve never known.

Yet the picture of cities—and New York in particular—that has been emerging from the work of social scientists is that the people living in them are actually less lonely. Rather than driving people apart, large population centers pull them together, and as a rule tend to possess greater community virtues than smaller ones. This, even though cities are consistently, overwhelmingly, places where people are more likely to live on their own.

A couple of months ago, John Cacioppo, the director of the Center for Cognitive and Social Neuroscience at the University of Chicago, decided to spend his one free evening in New York indulging in a favorite out-of-towner’s cliché, which in his business also qualifies as field research: watching strangers in Grand Central Terminal. “You’d see these people walking in all these different ways and at different paces, and all of a sudden, they’d be synchronized,” he says. Cacioppo has a mild presence, with a soft voice and a slim frame, but the second he starts talking about this stuff, he buzzes like a live cable. “If they were white dots on a black field,” he continues, “you could tell who belonged to who, just based on the synchrony of the white dots.”

Photo: Gail Albert Halaban/Courtesy of Robert Mann Gallery. The creation of these photographs was funded in part by the Design Trust for Public Space.

The traditional social-science gloss on a metropolitan node like Grand Central isn’t all that different from Stephen Sondheim’s observation in Company: “Another hundred people just got off of the train … It’s a city of strangers / Some come to work, some to play.” Grand Central is a glorious space, but it’s also vast and impersonal, teeming with solitary commuters rather than one’s own kin and kind. Might some people not come away from such a place feeling profoundly estranged? Like they hadn’t a friend in the world?

They could. But in the sunshiny, low-crime New York of 2008, Grand Central feels much more like a village green than the melancholy nowhereland of Sondheim’s vision (or worse, Travis Bickle’s open-air asylum). There are tourists asking other tourists to take pictures of them; cops kibitzing with passersby; friends meeting friends to go for drinks. “All these transient connections were forming,” Cacioppo marvels. “These people weren’t even conscious of the many ways they were forming.”

Cacioppo, co-author of W.W. Norton’s recently published Loneliness, is part of the school of evolutionary psychologists—and certain biologists too—that believes our species wouldn’t have survived without a cooperative social instinct. In their book, Cacioppo and his co-author, the science writer William Patrick, argue that loneliness, like hunger, is an alarm signal that evolved in hominids hundreds of thousands of years ago, when group cohesion was essential to fight off abrupt attacks from stampeding wildebeests. It’s nature’s way of telling us to rejoin the group or pay the price. “Nature,” they simply write at one point, “is connection.”

It’s a controversial theory, certainly, not least because it’s post-hoc and therefore can’t be proved. But it has beguiling consequences for city dwellers. From Cacioppo’s point of view, our large brains didn’t evolve in order to do multivariable calculus or compose sonatas. They evolved in order to process social information—and hence to work collaboratively. “And if you look at any city,” he says, “you see that we have the capacity, as a species, to do so. They show we can work together, we can trust one another. We couldn’t even drive through city streets if we didn’t trust that people would follow rules that protect the group.”

Cities, in other words, are the ultimate expression of our humanity, the ultimate habitat in which to be ourselves (which may explain why half the planet’s population currently lives in them). And in their present American incarnations—safe, family-friendly, pulsing with life on the street—they’re working at their optimum peak. In Cacioppo’s data, today’s city dwellers consistently rate as less lonely than their country cousins. “There’s a new sense of community in cities, an increase in social capital, an increase in trust,” he says. “It all leads to less alienation.”

A raft of papers and polemics have come out in the last decade that argue Americans are lonelier. The starkest was a survey in The American Sociological Review reporting that the average number of people with whom Americans could “discuss important matters” dropped from three to two between 1985 and 2004, and that the number of Americans who felt they had no confidants at all had more than doubled, from 10 to 24.6 percent. But the most famous of the genre—the work that launched a thousand debates—was Bowling Alone, a meticulous chronicle of scary numbers by Harvard public-policy expert Robert Putnam. It showed that almost every measurable form of civic participation, from church attendance to union membership to bowling leagues, declined in the waning decades of the last century. The book had plenty of critics, who pointed out that Putnam focused too much on obsolescent activities and organizations (card-playing, the Elks); that he gave short shrift to new, emerging forms of social capital, like Internet groups; and that the declines he documented were fairly modest. It didn’t matter. The book resonated, vibrantly, with laymen and politicians alike, becoming an instant best-seller and catapulting Putnam into the rarefied company of presidential contenders and world leaders. He’s worked with Bill Clinton, George W. Bush, and Tony Blair. He also met with Barack Obama during his campaign.

There are good public-health reasons to be concerned about loneliness. In the last couple of decades, researchers have started measuring the effects of social isolation, and they aren’t pretty. There’s been an avalanche of studies, for instance, showing that married people are happier and healthier, while the odds of dying increase significantly among the recently widowed, something known as the “widowhood effect.” There’s evidence suggesting that strong social networks help slow the progression of Alzheimer’s. There’s even better evidence suggesting that weak social networks pose as great a risk to heart-attack patients as obesity and hypertension. There’s also evidence to suggest that the religious people who live the longest are the ones who attend services most frequently rather than feel their beliefs most deeply. (It’s not faith that keeps them alive, in other words, but people.)

Photo: Gail Albert Halaban/Courtesy of Robert Mann Gallery. The creation of these photographs was funded in part by the Design Trust for Public Space

Studies show that loneliness is associated with morning surges in cortisol, the stress hormone, and increased vascular resistance, which results in higher blood pressure. They also show the lonely drink more, exercise less, get divorced more often, and have more family estrangements and run-ins with the neighbors. And they’re fatter. In one of my favorite experiments described in Loneliness, students were divided into two groups and told to evaluate … bite-size cookies. Specifically, researchers took aside each of the kids in one group and told them that no one wanted to work with them, so they’d have to work on their own. The others, by contrast, were each privately told that everyone wanted to work with them, but they’d still have to work on their own because it would be impossible to work with so many people. Then all of the participants were handed a plate of cookies and told to evaluate them. On average, the ones who had been told they were universally liked ate 4.5. Those who had been told they’d been universally rejected ate 9. “Is it any wonder we turn to ice cream,” the authors ask, “when we’re sitting at home feeling all alone in the world?”

Given how many New Yorkers live alone—in Manhattan, 25.6 percent of households are married, whereas the national average is 49.7—one would think we’d be at an increased risk for practically all these conditions. But Cacioppo points out that loneliness isn’t about objective matters, like whether we live alone. It’s about subjective matters, like whether we feel alone. To determine how satisfied people feel with their relationships, research psychologists generally rely on a twenty-question survey called the UCLA Loneliness Scale, which breaks down our connections into three groups: intimate (whether we have a partner), relational (friends), and collective (church, colleagues, baseball teams, etc.).

The results of these surveys have crucial—and positive—consequences for urban environments. Loneliness, it turns out, is relative. Widows are likely to feel better in a community with more widows (Boca Raton, Florida, say) than a community with only a few single elderly women. And singles are likely to feel better in a town with more singles … like New York. It’s true that marriage is still the best demographic predictor of loneliness. But Cacioppo stresses it’s a very loose predictor. People can have satisfying connections in other ways, after all, and people in bad marriages might as well be on their own: Cacioppo’s latest study, based on a sample of 225 people in the Chicago area, shows that those in unhappy marriages are no less lonely than single people, and might even be more so. Nor do rotten marriages do much for your health. A couple of years ago, Cacioppo teamed up with Linda Waite, co-author of The Case for Marriage: Why Married People Are Happier, Healthier, and Better Off Financially, whose conclusions about the health-positive effects of the institution drove feminists and fatalists like myself into a tizzy. They recruited a new pool of sample subjects and more or less asked the same questions Waite originally did, but also inserted questions to see if their participants were lonely. And what did they discover? That married people were indeed healthier—if they weren’t lonely in their marriages. If they were, the health benefits were so negligible the researchers considered them statistically insignificant.

No one disputes the value of a good marriage, of course. Andrew Oswald, an economist at the University of Warwick, in fact tried to calculate that value, based on tens of thousands of happiness surveys collected here and in the U.K., and found that it’s worth $100,000—or roughly doubling your salary, because working Americans earn, on average, $46,996 per year. But you know what else was worth $100,000? A large circle of friends. And it turns out that Aristotle was right when he wrote in The Nicomachean Ethics that friends are the glue that binds cities together. In study after study, urban dwellers have a more substantial social network. In his 1982 classic about Californians, To Dwell Among Friends: Personal Networks in Town and City, the Berkeley, California–based sociologist Claude Fischer found a 40 percent uptick in the size of friendship-based social networks moving from semi-rural areas into the urban core. Even the recent study that found we had fewer confidants found better news for city dwellers. “Based on what I’m seeing,” says Matthew Brashears, one of the authors of the survey, “networks in large communities may have gotten smaller, but people in large communities still appear to have bigger networks than people in small.”

“In our data,” adds Lisa Berkman, the Harvard epidemiologist who discovered the importance of social networks to heart patients, “friends substitute perfectly well for family.” This finding is important. It may be true that marriage prolongs life. But so, in Berkman’s view, does friendship—and considering how important friendship is to New Yorkers (home of Friends, after all), where so many of us live on our own, this finding is blissfully reassuring. In fact, Berkman has consistently found that living alone poses no health risk, whether she’s looking at 20,000 gas and electricity workers in France or a random sample of almost 7,000 men and women in Alameda, California, so long as her subjects have intimate ties of some kind as well as a variety of weaker ones. Those who are married but don’t have any civic ties or close friends or relatives, for instance, face greater health risks than those who live alone but have lots of friends and regularly volunteer at the local soup kitchen. “Any one connection doesn’t really protect you,” she says. “You need relationships that provide love and intimacy and you need relationships that help you feel like you’re participating in society in some way.”

Eric Klinenberg is a sociologist at NYU who’s in the midst of writing a book called Alone in America. He and his researchers have interviewed over 200 “solitaires” (his term) about their experiences, 160 of them from New York City. “I’m concerned about poor and elderly people who live alone,” he says. “I’m concerned about the sick who live alone. But we have to address the question of why, in other stages of their lives, people are opting to be alone, and we have to wrestle with the question of why many people who are elderly would rather live alone than move in with their children.” He offers a few hypotheses: That living alone is a crucial rite of passage into adulthood. That it’s a sign of economic achievement. That it’s a form of self-cultivation and living authentically, a reaction to the stifling compromises made by the cornered souls of Mad Men.

In my own life, I’d make the case that my single friends gave me the imagination to envisage a life without marriage, which meant I didn’t pair off too young. I also don’t think I’m going out on too weak a limb when I stipulate that cities, in which we have a large network of companions and a wide variety of activities to do with them, are better for marriages generally. The relationship researcher Arthur Aron has pointed out that new experiences, rather than repeated favorites, are the best way to keep romantic feelings alive in a marriage, based on a series of six studies of hundreds of couples.

Now seems like a good time to point out that New York State is tied for the fifth-lowest divorce rate in the nation. Isn’t it possible our marriages are simply better here?

And to the extent that suicide results from the tragic failure to socially integrate—one of the main ideas in Émile Durkheim’s 1897 classic, Suicide—then New York City’s suicide rate says something even more profound: New York State’s suicide rate is currently the third lowest in the nation (second if you discount Washington, D.C.), at 6.2 percent, and the city’s rate is even lower, at 5.4 percent. According to a report issued by the state’s Office of Mental Health, in fact, suicide statistics in New York follow a simple formula: The less populous the county, the higher the rate (with superdense Kings County, or Brooklyn, boasting the second lowest, at 4.4 per 100,000). The United States follows the same pattern, with suicides rising the more rural the area becomes. States with the worst suicide rates are the least dense. (Montana, Nevada, Alaska, New Mexico, and Wyoming are ranked, respectively, one through five.)

In terms of ameliorating loneliness, “friends substitute perfectly well for family,” says Harvard epidemiologist Lisa Berkman.

In the last decade, urbanism has converged, to some extent, with another field of study: Internet use. It’s probably not an accident. Both cities and the Internet are at once highly atomized and elaborately connected milieus that encourage both solitude and interaction with the diverse, bountiful unwashed. And like city solitaires, Internet users were also once identified as antisocial loners, painfully awkward people who vanished into the green-gray light of their computer screens rather than joining the warm community of man. In the beginning, studies even showed this to be true (or that users were shy, anyway). But not once three-quarters of the public started using the Internet.

“The idea that you’re isolated when you’re online is, to me, just wrong,” says Keith Hampton, a sociologist at the University of Pennsylvania who did an extensive ethnography of “Netville,” a new, 100 percent wired community in suburban Toronto. “It’s an inherently social medium. What starts online moves offline, and what starts offline goes online.” Which explains why the people with whom you e-mail most frequently are your closest friends and romantic partners. “Online and offline life are inherently connected,” he says. “They’re not separate worlds.”

In fact, many Internet and city behaviors we consider antisocial have social consequences. Think of people who lug their laptops into public settings. In 2004, Hampton and his colleagues looked at just those people—at Starbucks, in fact, in Seattle and Boston—and concluded that a full third of them were basically using their laptops and interacting at the same time. (Cafés, in other words, were like dog runs, and laptops were like pugs, encouraging interaction among solitaries.) Hampton did a similar study of laptop users in Bryant Park, and the same proportion, or one-third, reported meeting someone they hadn’t before. Fifteen percent of them kept in touch with that person over time (meaning that about 5 percent made lasting ties out of a trip to Bryant Park with a laptop).

It’s easy to see the parallels here between attitudes toward online use and attitudes toward solitary living. Perhaps there was once a time when living alone meant you were a hopeless shut-in. But you can’t exactly say this if 50 percent of the households in Manhattan contain just one person. Like Internet users, solitaires have a permanent and ambient sense of the world beyond their living rooms and a fluid sense of when to join it and when to retreat. Klinenberg, the NYU professor who is writing about living alone, points out that single people are partly responsible for the vibrancy of New York’s public life: “We know from marketing surveys that single people go out more than couples,” he notes. “They’re more likely to go to restaurants, to bars, and to clubs. A lot of people who live alone say it’s very hard to enter their apartments and stare at the walls when there’s so much going on outside.”

Conversely, married people—women especially—have smaller friendship-based social networks than they did as single people, according to Claude Fischer. In a recent phone conversation with the sociologist, I mentioned a related curiosity I came across in a paper about the elderly and social isolation in New York City: The neighborhoods where people were at the greatest risk, it seemed, were in neighborhoods where people seemed very married—family neighborhoods, in fact, like Borough Park and Ridgewood. “That’s not strange at all,” he says. “They’re the prime category of people to be isolated.” He explains that these people “aged in place,” as sociologists like to say, staying in the homes where they raised their own families. Then their spouses died, and so did their cohort (or it moved to a retirement community), and they’re suddenly surrounded by strange families, often of different classes or ethnic backgrounds, with whom they’re likely to have far less in common. “Unless they have children living nearby,” he says, “they’re likely to be quite isolated.”

I’m familiar with a younger version of this. When the New Yorkers I know feel lonely—single women especially—it’s a product, too, of feeling asynchronous with their cohort. I myself felt this way until fairly recently. James Moody, a network guru at Duke University, notes that there’s a time in the lives of young professionals when they retreat deep into their silos, trying to make partner, get tenure, write their books, complete their residencies, or whatever it is that they’re hoping to do. If they’re lucky, they’re married, which helps sustain them through the work isolation. Then the next stage comes when they’re working hard in their newly minted careers (as partners, tenured professors, authors, doctors, or whatever it is they’re doing). And again, they’re fairly cut off socially, but they’re buoyed, one hopes, by the presence of a family at home. But if someone is out of step with this pattern—not partnered off, say, while still working really hard—New York can be a challenging place.

But the fact remains that a city, New York especially, might be the best place to ride out that period of lonely toil. Because New York, like the Internet, also offers a rich network of acquaintances, or what sociologists like to call “weak ties.”

There are sociologists who will argue that weak ties are the bane of modern life. We are drowning in a sea of them, they’ll say—networking with colleagues rather than socializing with friends, corresponding online with lots of people we know only moderately well rather than catching up with our nearest and dearest on the phone. Bowling Alone is, to some extent, one long elegy for the strong ties we’ve lost, whether they’re the bowling leagues of Pittsburgh or the Hadassahs of New Jersey.

And there’s no doubt that weak ties can distract and enervate us. How many families sit down at dinner together with the best of intentions, only to find themselves drawn into their own individual worlds—texting on their BlackBerrys, yakking on their cells? (The cover art for Elsewhere, U.S.A., the fine upcoming book by NYU sociologist Dalton Conley, says it all: a family sitting at the dining-room table, each member staring at his or her own laptop.)

But having lots of weak ties is also wonderful for many things—including finding stronger ties. As Mark Granovetter wrote in his seminal 1973 essay, “The Strength of Weak Ties,” they’re much better at helping us find jobs because they offer us diversity and breadth. The same goes for love. Think about it: If you’re single, you already know all your friends’ single friends. It’s your acquaintances’ single friends you don’t know.

Viewed in this light, networking with acquaintances, of whom we all have many in New York, is hardly a shallow enterprise or waste of time. It’s through these people that we find husbands, wives, life partners, better jobs. Why should we begrudge that any more than we’d begrudge going on Nerve? Or Monster.com?

Weak ties offer other advantages in cities. They’re crucial to collective political action—your closest friends aren’t enough to start a movement—and they’re better than strong ties, believe it or not, for protecting neighborhoods, for the same reason: Banding together with those you know well isn’t enough to keep a whole community safe. Weak ties are essential to the creative economy, as Richard Florida pointed out in The Rise of the Creative Class, because diversity breeds innovation (and more diversity).

There is even evidence that weak ties simply make us feel better. According to Loneliness, the advice your mother gives you when you’re depressed—Get out of the damn house, would you?—turns out to be right. For most people, being in the simple presence of a friendly person helps us reregulate our behavior if we’re feeling depressed in our isolation. We are naturally wired not just to connect with them but to imitate them—which might be a good idea, if our impulses at that moment are self-destructive. Cacioppo and Patrick cite a range of studies showing that students in classes with the best rapport imitate each other’s body language; same goes for athletes on winning teams. The presence of other human beings puts a natural limit on how freakily we can behave. And where better to find them than in cities, where we have more ties? (Think about the sociopathic kids who shot other kids in Red Lake, Minnesota; at Northern Illinois University; at Virginia Tech—what do they have in common? They were living in isolated places.) Robert Sampson, paraphrasing Durkheim, puts it this way: “The tie itself provides health benefits. That’s where I started with my work on crime.”

So now I’m thinking back on all those connections Cacioppo witnessed in Grand Central. “Other species, like penguins, they rely on huddles for survival,” he told me. “In terms of collective structures, they’re pretty minimal and boring. But people have the capacity to make all kinds of transient connections. New York has an infinite number of them.”

He was describing the ballet of the train station. But his description could just as easily have applied to the Internet. Think about it: Serendipitous encounters between people who know each other well, sort of well, and not at all. People of every type, and with every type of agenda, trying to meet up with others who share that same agenda. An environment that’s alive at all hours, populated by all types, and is, most of the time, pretty safe. What he was saying, really, was that New York had become the Web. Or perhaps more, even: that New York was the Web before the Web was the Web, characterized by the same free-flowing interaction, 24/7 rhythms, subgroups, and demimondes.

Hampton says he views the Internet as the ultimate city, the last stop on the continuum of human connectedness. I’d argue that New York and the Internet are about the same, in the way that a large bookstore feels like it offers just as many possibilities as Amazon.com—maybe slightly less inventory, but more opportunities to stumble on things you might not have otherwise. Whichever the case, what the Internet and New York have in common is that each environment facilitates interaction between individuals like no other, and both would be positively useless—would literally lose their raison d’être—if solitary individuals didn’t furiously interact in each. They show us, in trillions of invisible ways every day, that people are essentially nothing without one another. We may sometimes want to throttle our fellow travelers on the F train. We may on occasion curse our neighbors for playing music so loud it splits the floor. But living cheek-by-jowl is the necessary price we pay for our well-being. And anyway, who wants to ride the subway alone?