The Buddy System: How Medical Data Revealed Secret to Health and Happiness
But Christakis and Fowler were skeptical of such claims. They knew that social habits are stubborn things. So they persuaded a university to let them analyze the Facebook pages of its students, devising a clever way to distinguish between casual friends and deeper emotional connections. Close friends, they hypothesized, would post pictures of one another on their Facebook pages, since the relationship wasn't purely virtual.
After analyzing thousands of photos, the scientists found that, on average, each student had 6.6 close friends in their online network. In other words, nothing has really changed; even the most fervent Facebook users still maintain only a limited circle of intimates.
"On Facebook, you've got a few close friends and lots of people you barely know," Fowler says. "Because the cost of information transmission is so low"—that is, the site makes it easy to communicate—"we end up staying in touch with more acquaintances. But that doesn't mean we have more friends."
Although the scientists are fascinated by the online world—"Facebook could become a revolutionary data set for people studying networks," Fowler says—their central research tool remains those handwritten papers salvaged from the Framingham Heart Study. In the four years since Christakis and Fowler built their first social map, they've published several groundbreaking papers documenting the network's influence on everything from cigarette addiction to happiness. In some cases, they've found that the impact of networks disappears abruptly after three degrees of separation. (In other words, if a friend of a friend of a friend stops smoking, then we are also significantly more likely to quit. But more-distant relationships have no effect; they are beyond the "social frontier.")
Although Christakis and Fowler have begun to study the variables, such as genetics, that determine a person's place within a social network—whether we're in the well-connected center or exiled to the fringe, which reflects popularity—they emphasize that there is no ideal social location. During a flu epidemic, the periphery is the safest place, since people with fewer connections are less exposed to the virus. But being on the fringe also reduces access to gossip and resources, which radiate out from the center. Because networks transmit the stuff of life—from happiness to HIV—evolution has generated a diversity of personality traits, which take advantage of different positions within the group. There are wallflowers and Wilt Chamberlains, shy geeks and "super-connectors." According to Christakis and Fowler, there is no single solution to the problem of other people. Individual variation is a crucial element of every stable community, from the Aborigines of Australia to the avatars of Second Life.
And because we're social primates, such communities are essential. When we're cut off from our network, we slip into a spiral of loneliness and despair, which severely affects our health. "Your friends might make you sick and cause you to gain weight," Christakis says, "but they're also a source of tremendous happiness. When it comes to social networks, the positives outweigh the negatives. That's why networks are everywhere." People, in other words, need people: We are the glue holding ourselves together.
Studying the self-reported moods of Framingham subjects, Christakis and Fowler found that happy people have happy friends (and unhappy people, unhappy friends). Examining smiles in Facebook portraits, they found the same pattern: Even online, social networks gather around joyful expressions.
Contributing editor Jonah Lehrer (email@example.com) wrote about the neuroscience of magic in issue 17.05.