RENEE MONTAGNE, host:
This is MORNING EDITION from NPR News. Good morning. I'm Renee Montagne.
In Your Health today, new research suggests that if your spouse gives up cigarettes you're nearly 70 percent more likely to quit too. Likewise, if a friend or even a friend of a friend stops smoking, you're more likely to quit.
NPR's Allison Aubrey reports on just how far this effect can go.
ALLISON AUBREY: Sheila Jennings and Tom White met a few days ago at an outdoor cafe in Adams Morgan, a neighborhood in Washington, D.C. There on the patio a sliver of sun illuminating some of the last feet of public space where smoking is still acceptable, Sheila opened a pack of cigarettes. Before she lit up she asked Tom, who was sitting at the next table over, if he minded.
Ms. SHEILA JENNINGS (Smoker): I thought in due respect I should ask.
Mr. TOM WHITE (Smoker): She asked me if it was OK if she smoked. I turned around. I was like, no, it's totally cool. I am too. And she kind of laughed and then we just started talking.
AUBREY: Down the street, Tom's friend Rusty Sticha had just gotten off work at a local bookstore and was walking toward the cafe to meet his girlfriend. When Tom and Rusty spotted one another, they stopped to say hello and catch up for a minute.
Mr. RUSTY STICHA: Take it easy. I'm going to go play some pool.
Mr. WHITE: Have a good one.
AUBREY: Rusty, it turns out, is not a smoker. At least not anymore, thanks to the influence of his girlfriend.
Mr. STICHA: I just quit again like a month ago, so it's very recent.
AUBREY: Was it hard?
Mr. STICHA: This is about the fifth time I've quit. It gets easier each time.
AUBREY: Especially now, when someone close to him is helping him kick the habit.
So here's the question. Is it possible that the influence of Rusty's girlfriend could extend to Tom? Or even to Sheila, who's just a mere acquaintance? Two researchers who've been studying the dynamics of social networks say yes, it's likely.
Nicholas Christakis is with Harvard Medical School.
Professor NICHOLAS CHRISTAKIS (Harvard Medical School): There's no doubt that people are influenced by the behaviors of individuals that are not just one degree of separation from them, but two and three degrees of separation from them. There's a kind of cascading influence. And if I had to bet I would bet that Tom is going to be more likely to quit now than he was before. And this cascade might've been put into motion by his friend's girlfriend.
Christakis isn't just shooting from the hip here. He and his colleagues have actually documented this cascading effect. Their work began kind of serendipitously, when they stumbled upon a trove of paper records from a heart study launched in the town of Framingham, Massachusetts back in the early 1970s.
Professor CHRISTAKIS: So we were able to recover these paper records and computerize them and reconstruct the social ties of a total of 12,000 people.
AUBREY: The beauty of the records is that they had information on everybody who started or stopped smoking, as well as social contacts. The records were updated continuously over three decades.
Professor CHRISTAKIS: Not only for any given individual did we know who their friends and family and co-workers and neighbors were, but for those friends, families, co-workers and neighbors we knew what their friends, family, co-workers and neighbors were. So we were able to go out well beyond six degrees of separation.
AUBREY: It turns out that the people closest to us in social space influence us the most, perhaps a validation of the obvious. But Christakis says there's more here than just a simple copycat effect. His study shows people stop smoking in droves or clusters, as if there were a kind of hive intelligence or a synchronicity to it.
What may be most interesting about the social network findings is who's left still smoking at the end of this three decade period when tobacco use dropped off substantially nationwide.
Christakis's colleague James Fowler of U.C. San Diego explains. He says in 1972 smokers were as likely to be positioned at the center of a social network as nonsmokers. The metaphor for being at the center would be standing at a party talking to 10 people.
Professor JAMES FOWLER (University of California San Diego): But by the end of the party, by the end of our 32-year study, the people in the center of the room are not smoking. And the people who continue to smoke have been literally pushed to the outside of the party, so that they're in places where they're only connected to one or two other people.
AUBREY: Tom White, one of the smokers from the cafe, says yeah, he can relate. Smokers do feel isolated these days.
So you're OK with being on the sort of outskirts or sort of the fringe.
Mr. WHITE: I don't have any choice. I don't like it, but I'm willing to be there. I'm willing to stay here.
AUBREY: The more smokers segregate themselves into islands on the periphery, the harder they may be to reach, says Dr. Steve Schroeder. He directs a Smoking Cessation Leadership Center at U.C. San Francisco.
Dr. STEVE SCHROEDER (Director, Smoking Cessation Leadership Center): Only about 3 percent of smokers who try to quit can quit on their own.
AUBREY: But using the power of social networks to pull people away from the sidelines might help drive down smoking rates even more.
Allison Aubrey, NPR News.