Editor’s note: This story was originally published in 2015.

I often think about a piece I read in the Atlantic, by Julie Beck, called "How Friendships Change in Adulthood." I suspect it will ring true for Vox readers of, uh, a certain age. Like my age, for instance. Old, is what I'm saying.

I do think, however, that Beck left out an interesting piece of the puzzle. Our ability to form and maintain friendships is shaped in crucial ways by the physical spaces in which we live. "Land use," as it's rather aridly known, shapes behavior and sociality. And in America we have settled on patterns of land use that might as well have been designed to prevent spontaneous encounters, the kind out of which rich social ties are built.

We get by with a little less help from our friends

It's a familiar tale that Beck tells: Early in life, friendships are central to our development and sense of self. This is true right up through to those early post-collegiate years, when everyone is starting out in their professional lives.

And then people get married. They have kids. Their parents get older and need more care. They settle into careers. All those obligations — spouses, kids, family, work — are things we have to do. Friendships are things we choose to do. And that means, when time constricts and things get busy, friendships often get bumped.

So as we get older, time with friends tapers off. "[In a study we did,] we asked people to tell us the story of the last person they became friends with, how they transitioned from acquaintance to friend," researcher Emily Langan told Beck. "It was interesting that people kind of struggled":

In a set of interviews he did in 1994 with middle-aged Americans about their friendships, [researcher William] Rawlins [of Ohio University] wrote that, "an almost tangible irony permeated these adults' discussions of close or ‘real’ friendship." They defined friendship as "being there" for each other, but reported that they rarely had time to spend with their most valued friends, whether because of circumstances, or through the age-old problem of good intentions and bad follow-through: "Friends who lived within striking distance of each other found that… scheduling opportunities to spend or share some time together was essential," Rawlins writes. "Several mentioned, however, that these occasions often were talked about more than they were accomplished."

This is a sad story. People almost universally report that friendships are important to their happiness and well-being. They don't want to lose touch with friends and stop making new ones. They lament it constantly. (I can testify to all of this firsthand.)

But as the habits of family and work settle in, friendships become an effort, and as every tired working parent knows, optional effort tends to get triaged.

Does it have to be this way?

Our missing tribes

There's a temptation to say that this is inevitable, just the way things are. People grow up, they don't hang out with friends as much anymore. It's kind of sad, but that's just how it is.

But it is not inevitable. In fact it's quite new! For the vast majority of Homo sapiens' history, we lived in small, nomadic bands. The tribe, not the nuclear family, was the primary unit. We lived among others of various ages, to which we were tied by generations of kinship and alliance, throughout our lives. Those are the circumstances in which our biological and neural equipment evolved.

It's only been comparatively recently (about 10,000 years ago) that we developed agriculture and started living in semi-permanent communities, more recently still that were thrown into cities, crammed up against people we barely know, and more recently still that we bounced out of cities and into suburbs.

So everything about how we live now is "unnatural," at least in terms of the scope of human history. Unnatural doesn't necessarily mean bad — our long lifespans are unnatural too — but it should remind us that the particular socially constructed living patterns common today have shallow roots.

There's nothing fated or inevitable about each of us living in our own separate nuclear-family castles, with our own little faux-estate lawns, getting in a car to go anywhere, never seeing friends unless we make an effort to schedule it.

Why should it require explicit scheduling to see a friend who lives "within striking distance"? Why shouldn't proximity do some of the work? The answer, for many Americans, is that anything beyond a few blocks away might as well be miles; it all requires a car. We do not encounter one another in cars. We grind along together anonymously, often in misery.

The loss of spontaneous encounters

Why do we form such strong friendships in high school and college and form comparatively fewer as the years go on?

I read a study many years ago that I have thought about many times since, though hours of effort have failed to track it down. The gist was that the key ingredient for the formation of friendships is repeated spontaneous contact. That's why we make friends in school — because we are forced into regular contact with the same people. It is the natural soil out of which friendship grows.

This study isn't it, but it's similar, to wit:

The researchers believed that physical space was the key to friendship formation; that "friendships are likely to develop on the basis of brief and passive contacts made going to and from home or walking about the neighborhood." In their view, it wasn’t so much that people with similar attitudes became friends, but rather that people who passed each other during the day tended to become friends and later adopted similar attitudes.

And this also reinforces the point:

As external conditions change, it becomes tougher to meet the three conditions that sociologists since the 1950s have considered crucial to making close friends: proximity; repeated, unplanned interactions; and a setting that encourages people to let their guard down and confide in each other, said Rebecca G. Adams, a professor of sociology and gerontology at the University of North Carolina at Greensboro. This is why so many people meet their lifelong friends in college, she added.

This kind of spontaneous social mixing doesn't disappear in post-collegiate life. We bond with co-workers, especially in those scrappy early jobs, and the people who share our rented homes and apartments.

But when we marry and start a family, we are pushed, by custom, policy, and expectation, to move into our own houses. And when we have kids, we find ourselves tied to those houses. Many if not most neighborhoods these days are not safe for unsupervised kid frolicking. In lower-income areas there are no sidewalks; in higher-income areas there are wide streets abutted by large garages. In both cases, the neighborhoods are made for cars, not kids. So kids stay inside playing Xbox, and families don't leave except to drive somewhere.

Thus, seeing friends, even friends within "striking distance," requires planning. "We should really get together!" We say it, but we know it means calls and emails, finding an evening free of work, possibly babysitters. We know it would be fun. But it's very easy just to settle in for a little TV.

Those of you who are married with kids: When was the last time you ran into a friend or "dropped by" a friend's house without planning it? When was the last time you had a unplanned encounter with anyone other than a clerk or a barista, someone serving you?

Where would it happen? The mall? Walmart? There are so few noncommercial public spaces where we mix and mingle freely with people on a regular basis.

Living with people

Say you're a family with children and you don't regularly attend church (as is increasingly common). There are basically two ways to have regular, spontaneous encounters with people. Both are rare in America.

One is living in a real place, a walkable area with lots of shared public spaces, around which one can move relatively safely and effectively without a car. It seems like a simple thing, but such places are rare even in the cities where they exist. (I live in North Seattle, undoubtedly coded as urban for census purposes, but my walkshed is pretty lame. Meanwhile, a few miles south of me they're building million-dollar single-family homes square in the middle of a perfect walkshed, right across from the zoo.)

A robust walkshed is an area in which a community of people regularly mingles doing errands, walking their dogs, playing in the parks, going to school and work, etc. Ideally, cities would be composed of clusters of such walksheds, connected by reliable public transit.

But we don't live in such a world. Walkable communities are very difficult to find in the US, and because there is such paucity of supply relative to demand, they are expensive, accessible only to the high-income. Places where they exist tend to have absurd zoning restrictions that prevent growing them. (Our own Matt Yglesias has much to say on these issues.)

The second, even more rare, is some form of co-housing. There are many kinds of co-housing, too many to get into in this post, but my favorite, a common model in Germany, is baugruppen, or building groups. I wrote an enthusiastic post about baugruppen here:

The basic idea is that a group of people comes together to work directly with architects and designers, bypassing developers, to build a shared dwelling that they own collectively (a co-op, basically). Taking developers out of the picture saves money — 25 to 30 percent in Berlin, where baugruppen are common — and opens up space for much more ambitious, innovative, and sustainable architecture. It also fosters cooperation and community among members of the collective.

In practice, baugruppen are basically like condos, but with much more robust shared spaces and collective ownership rather than developer ownership. (If you want to know much more about them, passivhaus designer Mike Eliason has a seven-part series I highly recommend. He summarizes it as "private owners collaboratively building affordable multifamily projects.")

The idea behind baugruppen, and co-housing generally, is that it's nice to live in an extended community, to have people to rely on beyond family. It's nice to have bustling shared spaces where you can run into people you know without planning it beforehand. It's nice to have nearby friends for your kids, places where they can play safely, and other adults who can share kid-tending duties.

Refusing to accept the status quo of default isolation

Both these alternatives — walkable communities and co-housing — sound exotic to American ears. Thanks to shifting baselines, most Americans only know single-family dwellings and auto-dependent land use. They cannot even articulate what they are missing and often misidentify the solution as more or different private consumption.

But I do not think we should just accept that when we marry and start families, we atomize, and our friendships, like our taste in music, freeze where they were when we were young and single. We shouldn't just accept a way of living that makes interactions with neighbors and friends a burden that requires special planning.

We should recognize that by shrinking our network of strong social ties to our immediate families, we lose something important to our health and social identities, with the predictable result that we are ridden with anxiety and loneliness. We are meant to have tribes, to be among people who know us and care about us.

To some extent, economic and employment trends have made us rootless. We move around much more and remain in jobs for less time (or work in the "gig economy"). We don't stay in one place the way our parents and grandparents did. Those trends, which have brought good along with bad, are likely irreversible.

But we can do something about the places where we live. We can make them more conducive to community and spontaneous social mixing. We know how to do it — it's just a matter of agreeing that we need it and changing policy accordingly.

VIDEO: 220 years of population shifts