The Village Effect: How Face-to-Face Contact Can Make Us Healthier and Happier (15 page)

In the United States, a nation preoccupied with its obesity epidemic, Christakis and Fowler’s finding made public health officials sit up and take notice. It also piqued the interest of the press. A front page
New York Times
article was headlined “Are Your Friends Making You Fat?” and Oprah’s production team and the
Colbert Report
came calling. The attention was karmic, given that Fowler was the one who had put some scientific meat on the bones of the rumored “Colbert Bump”—the surge in popularity that followed a politician’s appearance on the show.
²

Even more surprising than the idea that you can catch obesity from your best friend is the suggestion that it can move from one person to another and then to another within a social network, even if the first and third links in the chain never meet. The researchers came to this conclusion after comparing the Framingham data to a computer simulation of random relationships. In the Framingham sample, not only did obesity appear in clusters, serious weight gain seemed to move from contact to contact, petering out after three social links. As Christakis and Fowler point out in
Connected
, “The average obese person was more likely to have friends, friends of friends, and friends of friends of friends who were obese than would be expected due to chance alone,” suggesting, as they put it, “your friends’ friends can make you fat.”

After learning about obesity contagion, I couldn’t help but wonder: with friends like these, who needs enemies? And there was something else, too. As we saw in the previous chapter, the more intimate our connection to someone, the greater their influence on us. So how can we be influenced by someone we’ve never met?

First, as the researchers themselves note, friends are fairly likely to enjoy the same foods and have the same habits—that’s why they’re friends! So a friend of yours might like someone you’ve never met but who shares your interests and appetites. So it might not just be contagion at work but the effect of birds of a feather flocking together. Moreover, a participant in the Framingham Heart Study would likely have named a friend who was similar to her as her primary contact. Each person would resemble the person they’d nominated. Then, as these similar people started to have children, stopped jogging, or approached middle age—or all those things happened at once—their waistlines would expand, if not exactly at the very same time, then in a hiccuppy but still connected sort of way.

Indeed, in 2011 Fowler and Christakis, along with Jaime Settler, demonstrated how friends self-segregate at the genetic level. We’re drawn to people with whom we share matching clusters of nucleotides.
³
So, whatever our friends are doing, whether it’s drinking pitchers of beer or eating artisanal cheeses, we’re more likely to be doing it too, not only because monkey-see, monkey-do, but because we gravitate toward people who have the same cravings. Catching obesity from friends of friends could be more a matter of shared characteristics than social contagion, though friends who are in close proximity would certainly copy and influence each other too, amplifying the effect.

The researchers knew, of course, that social networks aren’t the only reason for the obesity epidemic. Still, when Christakis and Fowler created a computer animation of the spread of obesity, they expected to see it expand outwards in a predictable way—the way an epidemic spreads from Patient Zero or, as they put it, the way “a pebble is dropped in a still pool of water, and a concentric circle of waves moves away from it.” Instead they saw something messier.

Clearly there was more than one thing going on at once. Aside from social contagion and homophily, there could be other causes
of weight gain among friends, such as a new McDonald’s in the neighborhood (or in my case, a great ice cream shop), catalysts for eating that might have little to do with social influences. The researchers tested for this by seeing if the direction of the esteem one person had for another predicted the direction of contagion. If two people named each other as their closest contact, then one person’s weight gain should affect the other’s equally. But if I nominated my friend Rosie as my one person to contact and she nominated someone else, Rosie’s weight gain should affect my waistline more than my waistline would affect hers. And that’s what Fowler and Christakis found: the contagion was lopsided. Susan (who had nominated Rosie as her one important contact) would be 57 percent more likely to pack on the pounds if Rosie became a little broad in the beam first. But if Rosie had not nominated Susan in return, Rosie would be only 13 percent more likely to put on weight if Susan did. Christakis and Fowler attribute the difference between these two numbers to social contagion.

This conclusion is controversial, and statisticians and health economists have since disputed whether the difference between these numbers is meaningful.
⁵
Still, Christakis and Fowler’s ability to anticipate how obesity might spread via social ties within a single town is ingenious. And given what we know about mimicry, I think that they are right. Putting on weight
can
be infectious—as long as people have face-to-face contact, and especially if they’re tightly linked by an emotional bond.

But I doubt that there is a mysterious iCloud effect that causes people to sync their eating, drinking, or moods without genuine interaction. And this body of research rests on a single nomination—the name of that one Framingham resident who would know your whereabouts if the researchers couldn’t find you for a follow-up visit. But is that person always a close friend? When I was first reading these social network studies, I asked my husband, who was reading in his favorite chair across from me in the living
room, whom I should call if I couldn’t reach him on his BlackBerry about an upcoming doctor’s appointment. “Carole,” he answered, naming his highly competent administrative assistant. He looked up at me briefly over his stack of documents and added, “She has access to my agenda.”

Even if we don’t know why exactly, friends are indeed powerfully swayed by each other’s eating habits. Sarah-Jeanne Salvy, a psychologist at the University of Buffalo, has shown that we match our eating to what our friends are consuming, eating more when we’re face-to-face with people in our circle and less when we’re eating alone or with strangers.
⁶
This rings true to me. When I travel for work and eat alone, I eat the minimum, getting the job done in fifteen minutes. But if I’m lucky enough to be dining with friends, as I was when I attended a conference in Heidelberg a few years ago, then I’m happy to consume three courses over three hours in a candlelit restaurant—venison consommé with dumplings, herb-roasted free-range chicken with buttered greens and potatoes, and a goblet of red wine or two, followed by a confection made with pralines, crème anglaise, and meringue—at least 3,500 calories, all of which went down with no trouble at all, accompanied as it was by jokes, gossip, and stories. My four svelte companions ate those three courses too. Why do we eat more when we’re with friends or family than when we’re alone?

THE ROOTS OF COMMUNAL EATING

In 2008, the twelve-thousand-year-old remains of a middle-aged woman were unearthed from a burial site in a cave in the Galilee hills, along with the fossilized bones of seventy tortoises, three wild oxen, several mountain gazelles, two martens, an eagle, a wild boar, and a leopard. Our Mesolithic ancestors held big parties, apparently. On this occasion, archeologists surmise that they barbecued about 660 pounds of meat so that approximately thirty-five people could pay their respects to a recently deceased Natufian
woman—not excessive, I suppose, when it came to honoring someone they think was an important shaman. She certainly had status: she was buried with her skull resting on one tortoise shell and her pelvis elevated by half a dozen others.
⁷

But another reason this woman was mourned with a lavish feast is that eating together is a form of social glue, according to Natalie Munro and Leore Grosman, the two archeologists who investigated the burial site. The transition from a nomadic hunter-gatherer existence to life in settled communities meant that these mourners were living cheek by jowl with large numbers of people for the first time in human history. In other words, they now had neighbors. Anyone who has had to ask the folks next door to turn down their thumping hip hop or to curb their beloved cocker-doodle knows what that means. The inevitable interpersonal friction created by population density was eased by big communal parties; sharing food helped such ragtag bands cohere. Indeed, when people share food, they’re more likely to feel that they are part of a group and to compromise to resolve a conflict.
⁸
Who knew that the business lunch began in a dry Middle Eastern wadi where the area’s disparate residents gathered to gnaw on barbecued gazelle ribs? There may also have been pilaf on offer, made from the local barley they were just starting to cultivate, and a few dogs hanging around the fire—the first pets in history—begging for scraps.

Hunter-gatherers settling down where they could grow grain, instead of wandering around chasing wild herds, gave birth to village life about ten thousand years ago, and this settling down is what allowed our forebears to let the good times roll. Neil MacGregor, director of the British Museum, describes it as “a time of newly domesticated animals, powerful gods, dangerous weather, good sex and even better food.”
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But how did the villagers figure out who belonged?

INSIDERS AND OUTCASTS

In-groups and out-groups are such common features of human—and primate—societies that most of us have felt the pain of social ostracism at some point in our lives. Even if we’ve only experienced it in small doses, social isolation provokes a unique type of anxiety that distorts our ability to think clearly and to see events with any optimism, according to John Cacioppo and William Patrick in their book
Loneliness
. The roots of social pain are biological. Our ancestors wouldn’t have survived predators or privation for very long if they hadn’t belonged to an inclusive group. Living in a community is so essential to survival that an early warning system evolved that rings biochemical alarm bells when we’re ostracized. We experience these warnings as acute anxiety, which—like other metabolic warnings such as extreme hunger, thirst, or pain—essentially communicates the following message:
fix this or you’re finished
.
¹⁰

Enforcing the boundaries between in-groups and out-groups is the dark side of forming social bonds. When the leaders of Nazi Germany compelled twenty million people—German Jewish citizens stripped of their civil status, and deportees from nearly every country in Europe—to perform forced manual labor during the Third Reich, they wanted to ensure that they would be ostracized from mainstream German society. This wasn’t a given, despite the National Socialists’ racist propaganda campaign. One reason was that the forced laborers were assigned to work on family farms, in local businesses, and in factories under the supervision of ordinary citizens, whose feelings of empathy might have been aroused by the fate of their onetime neighbors and colleagues. How could empathy be avoided? One way was to forbid “Aryans” from sharing meals with the forced laborers. If anyone might be tempted to include them in the fabric of daily life in wartime Germany, the Third Reich created new social norms, publicized on posters, on the radio, and in daily newspapers. A cartoon called “Figure of the
Week,” published on April 18, 1943, in the
Amstettner Anzeiger
, illustrates how forced laborers were to be excluded from what was called the “community of the table.”
¹¹

“Figure of the Week,” Amstettner Anzeiger, April
18, 1943. (Image and Figure Credits
4.2
)

“Like the herd animals we are, we sniff warily at the strange one among us,” wrote anthropologist Loren Eiseley, hinting at how natural it feels to form a tight circle of family and friends and wall off others, especially in times of unease or uncertainty about scarce resources.
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Forcing people to eat or drink separately has long been used in traditional societies to humiliate and punish. Among the Pirahã Indians of Brazil, for example, the punishment for violating a social norm “begins with excluding someone from food-sharing for a day, then for several days, then making the person live some distance away in the forest, deprived of normal trade and social exchanges. The most severe Piraha sanction is complete ostracism,” writes Jared Diamond in
The World Until Yesterday
.
¹³
But until the Rwandan genocide, Nazi Germany was in a class of its own in its ability to manipulate the desire to belong to an identifiable group and transform it into xenophobia and a murderous hunt for scapegoats. If our Mesolithic ancestors held big feasts to help their fledgling communities cohere, racist movements do the opposite: they use food to exclude.