IRA FLATOW, host:
This is SCIENCE FRIDAY from NPR News. I'm Ira Flatow.
A little bit later, we'll be listening to some science sounds from the band They Might Be Giants. But first, how can something being done by your friends, some people you also may have never met before, they're friends of your friends, how can something affect you? Well, some of it sounds predictable, like maybe if you're friends or fans of a certain movie or their certain team, you're more likely to be a fan as well, right?
But new research into how we all interact has turned up some unusual findings, according to my next guests. For example, people you've never met may influence how fat you are or how happy you are or your likeliness to vote and - and now that so many of us part of social networks on the Web like Facebook or MySpace and Twitter and stuff like that, we may be influenced by strangers in ways that we may not have thought about.
Well, these - these authors have thought about it and they written about this stuff in their new book, "Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives." And that's what we're going to be talking about for the next part of the hour. Our number: 1-800-898-8255. You can also research, search us and then twitter us at scifri, at S-C-I-F-R-I.
Let me introduce my guests, authors of the new just out by Little Brown. Nicholas Christakis is a professor of medicine, of medical sociology and of sociology at Harvard University. And he joins me now from a studio at campus. Welcome to SCIENCE FRIDAY.
Professor NICHOLAS CHRISTAKIS (Harvard University): Thank you very much, Ira.
Prof. CHRISTAKIS: You are welcome.
FLATOW: And here with me in New York, James Fowler. He is an associate professor in the Center for Wireless and Population Health Systems in the Political Science Department at UC San Diego. As I say, he's here in our studios in New York. Welcome back…
Professor JAMES FOWLER (UC San Diego): I'm glad to be here.
FLATOW: …to SCIENCE FRIDAY. Going through, you've written magazine articles, stuff about that, and now the book is out. And - and the message seems to be that some big health issues - obesity, smoking - can be spread just like a disease. Is that right?
Prof. FOWLER: That's absolutely correct. And it's - it's actually bigger than that. It's bigger than being big. It's really about how everything that we do is influenced by our social networks. And so we have research that's come out over the last few years that shows that if your friend's friend's friend becomes obese, it increases the likelihood that you will be obese as well. And this can be a person that you don't know and have never met before. And so we get these chain reactions going from one person to another through close friendships where one person can be affected by other people. But we find this not just for obesity.
We find it for happiness, we find it for smoking, for depression, for loneliness, for drinking behavior, and a wide array of other things we talked about in the book.
FLATOW: Hmm. And Nicholas, why is that? Have you figured out why that is or you just know that it is?
Prof. CHRISTAKIS: Well, I mean, I think the basic point to stress is that in some sense we're all embedded in these vast social networks and that - and that the fact that human beings live out their lives in these intricate, extensive social networks is not a coincidence. Some other work that James and I have done suggests that there are ancient genetic roots to this kind of connectedness. And in a way we think of networks as a kind of - as a kind of matrix in which we're all embedded, or if you will, like the Force in "Star Wars," you know, it surrounds us, it affects us all, it's there everywhere. And, you know, most people nowadays are accustomed to talking about networks and they think about online networks that they can see but what they may not realize is that they're actually embedded in these living, breathing networks that surround us all, all the time, and have always done so.
FLATOW: Do you find that your spouse is one who is most influential or going to be someone else? How do - how do you, you know - or is it different for different kind of things?
Prof. CHRISTAKIS: Yeah, it's different for different kinds of things. And James and I often misunderstood when we are talking about this work that somehow we think everything spreads in networks, that's not true. Some things do and some things don't spread. And not everything that spreads spreads by the same mechanism. And different things spread differently. And so devil is often in the details. So spouses might be very important for certain phenomena but not for others. And in fact we do find variation between different categories of people with whom you might interact.
Prof. FOWLER: Right. So just for example, when we look at happiness, loneliness and depression, these are emotions or affective states. And there it seems like physical proximity is very important. You - in order for you to be influenced by someone who is close to you, they have to literally be physically close. But when it comes to behaviors and behavioral outcomes, like obesity or smoking or drinking, we found a remarkable result, that your friends who live hundreds of miles away have just as big an impact on you as your friends who live next door. And so there it seems like it's not just face-to-face contact. You know, with obesity it's not just sharing a meal with somebody…
FLATOW: Right.
Prof. FOWLER: …it's really sharing ideas, things that can cross the miles.
FLATOW: And you discovered…
Prof. CHRISTAKIS: So what…
FLATOW: I'm sorry, go ahead.
Prof. CHRISTAKIS: No, I was just going to say, so in essence what we are saying is that what really matters to a lot of these phenomena is who you know, not where you are. And these kinds of phenomenon, these social phenomenon that might spread, let's say, via social contagion, require a network path so they can reach from person to person and person to person to person and person to person to person. And I should stress, if I might, that many of the things that we talk about might seem very intuitive, that, you know, for example, what you're - the people you're in direct contact with might affect your behaviors is really not too surprising.
But what I think is surprising about some of the work that we've done is that we're able to show that larger groupings of people, people who don't even know each other, as you alluded to at the opening, might simultaneously show similar behaviors. Like a - like a herd of buffalo stampeding in one direction or other, for example, groups of humans might begin to show similar behaviors without coordinating those behaviors with each other deliberately.
FLATOW: So it's like how do all these school of fish know how to turn at the same time?
Prof. FOWLER: That's exactly right. That's exactly right. And the great thing about that is, is that, you know, we know from great studies now that the way that works is that the fish - they're not watching the whole school, they're just watching the fish next to them. And with human beings at the same, except that for us it's not physical proximity. It's social proximity. It's who we know, who we're connected to that really matters in terms of cohering the whole group.
FLATOW: And is that now being expanded because we have Internet, social groups, that who you - proximity means something different than it used to be physically living next door to one other? Could it be the proximity to your friends on, let's say, Facebook?
Prof. FOWLER: Well, one of the things that we do as we talk about the biological basis of our networks and then try to think about how is this going to affect our life online, and so we have a chapter in the book called "Hyper-connected…"
FLATOW: Right.
Prof. FOWLER: …which I think really characterizes the state of the world that we've been living in for about the last 10 years or so. And we make a number of arguments in that chapter, but the basic idea is that everything is different but the same, and I know this sounds a little pithy, but the idea is that -that just for example, we weren't built to have one hundred close friends, and so when someone tells you that they have a hundred friends on Facebook or a thousand friends…
FLATOW: Yeah.
Prof. FOWLER: …on Facebook, they're really not talking about the kinds of people who have influence over them. They're talking about acquaintances, not friends.
FLATOW: Right. Well, if you say something like obesity is contagious, and we have this giant outbreak of obesity in this country, are there key players in, you know, like, if you think of a disease being contagious, somebody is spreading it, are there key players in the social network that if you get to them and get them to lose weight, then all the other people might ripple through that? And then you'd - you know, you have the most effect by, sort of, I guess I'd call it leveraging, you know? Should you be looking for those folks, James, you know, to try to conquer this obesity epidemic?
Prof. FOWLER: Well, absolutely. And it's not just figuring out who to target, but it's also seeing how the structure of these relationships influences this spread. And so another thing we talk about in the book is sexually transmitted diseases…
FLATOW: Right.
Prof. FOWLER: …for example. There's been a lot of really great work by some of our colleagues on this, where what they're able to show is that different populations are connected in different ways. And it has enormous implications for - for how many different people will catch a disease and also for - for how widely a disease will spread. And these behaviors and emotions, they're really no different from diseases, because we transmit those things from person to person in very similar ways.
FLATOW: Well, let's talk about…
Prof. CHRISTAKIS: Could I?
FLATOW: Please - sure…
Prof. CHRISTAKIS: You know, I - what I was going to say was that on the obesity thing, I mean, when we started doing our work, it's important to emphasize we picked obesity to study first, not so much because it was a public health problem, although it is, and not so much because we were curious about the way the use of the language, the obesity epidemic, we were curious about whether obesity was epidemic more than metaphorically, could there be a transmission, but also - actually ironically - simply because it was something that was easy to measure, people's height and weight.
And when we started the work, we kind of thought that maybe we would be able to find, you know, Patient Zero, as it were, of the obesity epidemic, and actually we realized fairly early in the work that that was very naive, that in fact obesity was a multi-centric epidemic and that there were lots of places in the network where it was simultaneously popping up and then diffusing from the network.
Mr. FOWLER: And we have these great videos, right, that show this, that show this.
FLATOW: Go ahead, you were going to say the reason, Nicholas?
Mr. CHRISTAKIS: Well, no, what I was going to say - yeah, I mean, I don't know how much time to take describing this video moment…
(Soundbite of laughter)
Mr. CHRISTAKIS: Where James and I - it was - I tell this story all the time. It was, like, the most exciting and the most depressing moment of my scientific career, seeing that video for the first time. But to pick up the other point, though, is that leaving aside for a moment this issue that, okay, obesity is spreading, it's multi-centric, some other investigators have come along and done some computer modeling of the epidemic and evaluated different kinds of strategies that are informed by a deep understanding of network structure about how we might arrest or turn around this or any other health-related epidemic, in like cutting behavior in teens or smoking behavior or whatever you're interested in, and there are various strategies you can use.
Some of them are quite subtle. They're not just about targeting particular individuals. They have to do with the way groups are approached.
FLATOW: Is it better to be in the middle of the group or on the fringe of the group, or does it make any difference?
Mr. CHRISTAKIS: Well, let me ask you this. Okay, let me ask you this. Let me conjure up in your mind and in the minds of listeners an image of a network. Most people nowadays have seen this. It's become pop culture, and these networks have particular patterns. They're kind of dense knit of ties in the middle and a kind of thinning out in the end, kind of like Christmas tree lights, like a mass of Christmas tree lights on the floor. They're a big knot in the middle and they're kind of loose on the edges.
Okay, imagine every light is a person, and all the ties between them are the little, you know, wires that connect the Christmas tree lights. And now let me ask you this. A deadly germ is spreading through the network. Would you rather be a light on the edge or a light in the middle? Would you rather be a node on the edge of the network or in the middle?
FLATOW: I'd like to be on the edge. I want to get away, yeah.
Mr. CHRISTAKIS: Of course, of course, because in the middle you're buffeted on all sides by this epidemic, but this germ that's passing.
Now, what if a valuable piece of information were spreading through the network? Now where would you rather be?
FLATOW: Yeah, you'd like to be in the central location. You'd like to be the first to hear about it.
Mr. FOWLER: Right, and what this means is that if you think about these things over a very long period of time, you know, in evolutionary time, what we would expect to find is we would expect to find variation, that some people are going to be on the edge and some people are going to be in the center, and this is one of the reasons why we're starting to find even a genetic basis for our social-network locations.
FLATOW: All right, we're going to take a break and come back and talk lots more with Nicholas Christakis and James Fowler, author of "Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives." Our number, 1-800-989-8255. We'll talk a bit about more things that might be connected. Stay with us.
(Soundbite of music)
FLATOW: You're listening to SCIENCE FRIDAY from NPR News. I'm Ira Flatow. We're talking about how social networks work with Nicholas Christakis and James Fowler, authors of "Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives." Our number, 1-800-989-8255.
Last time you were on, James, you were talking about happiness spreading.
Mr. FOWLER: Yeah, that's right.
FLATOW: That was a little tidbit you gave us on the way to writing the book being published.
Mr. FOWLER: That's right, that's right.
FLATOW: That happiness can spread in different ways than we think it can spread.
Mr. FOWLER: Well, absolutely. I mean, a couple of the main things that we found out in the happiness study is that happiness spreads three degrees of separation, like many of these other things that we've been studying and other researchers have been studying, but also that happiness is an example of why you want to be in the center of the network, because the people in the center tend to be happier then people on the edges.
And along with other evidence that we found in a paper, we think that the reason why this is is because there are competing waves of emotions that run through the network. There are happy waves and there are unhappy waves, and what we find is that the happy waves actually spread more reliably than the unhappy waves.
FLATOW: When you say they spread…
Mr. FOWLER: Yes.
FLATOW: Give us a concrete idea by spreading. We know disease has a germ, it has a vector, it spreads that way. How does happiness spread through a third party, not even a second party?
Mr. FOWLER: Right, so just for example, you get married, right? And for most people, that's a happy event, and then you have friends, friends who share in your happiness, right? And so maybe as a consequence of you getting married, you get to spend more time with your friends, maybe you get to spend time with your friend's spouse, who you really like, and then that also changes your feelings. And then once you become happier, then the effect might spread even, you know, one more degree of separation.
And happiness can spread through a couple of ways. One is, like, we can share resources with other people, and we talk about this in the book, but another way that it can spread is that there's actually imitation between humans, this emotional contagion we talk quite a bit about in the book.
Just for example, we document a laughter epidemic that happened in Africa in the 1960s. It's a great story and it still puzzles scientists to this day. There was a group of girls in a school that started laughing uncontrollably, and it spread to several other villages, and we really don't know what the source was, but we were able to - the scientists were able to document just how far the laughter epidemic spread.
Mr. CHRISTAKIS: So I mean, most people are familiar with the idea of a transient or brief spread of an emotional state from one person to another. For example, James and I were giving a talk, and we said you know how when you're on the sub - in New York City, and we said, you know how when you're on the subway and one person smiles at you and then you just instinctively smile back? And people looked at us and said, no, we don't do that in New York.
(Soundbite of laughter)
Mr. CHRISTAKIS: Everywhere else that's a normal behavior. It's instinctive. In fact, Jane Goodall has done work with a play face in chimpanzees. One chimp will show a play face, then the other will, and there have been experiments as well, economist at Dartmouth Bruce Sakerdote(ph) - actually, no, this was work done by someone else, I think, on depression transmission in roommates.
And a variety of studies have looked at the transient spread of emotions, Elaine Hatfield(ph) and others, the transient spread of emotions from one person to another. But what James and I were interested in was not just the dyadic or person-to-person spread of emotions but what we call the hyper-dyadic or person-to-person-to-person or person-to-person-to-person spread of emotions, and we were interested in how this might be over a longer period of time, and the mechanism of this spread is multifarious.
There are many. They are biological, psychological and social, but the key idea from our perspective is that it becomes possible to think about human emotions as having a collective existence and not just an individual existence.
So most people think about how they feel as being something very personal in their bodies, and what we're arguing in essence is that you can begin to think about emotions the way you might think about a buffalo stampede.
So if you could fly over a stampeding herd of buffalo and talk to one of the buffalos and say why are you running to the left, the buffalo would say, well, I'm not running to the left, the whole herd is running to the left, and in a way that is sort of what's happening with human emotions.
The whole herd of people in one region of the network comes to evince a particular emotional state at a particular time, and in essence this is the core argument that we're making, that many phenomena, including, surprisingly, emotions, can have a kind of collective existence.
FLATOW: Can they be then mathematically modeled and be predictable?
Mr. FOWLER: Yes, I mean, absolutely. In our academic papers, that's what we do.
(Soundbite of laughter)
FLATOW: So people are not - are people going to say, oh, now you've taken my free will away from me, I'm just a herd of buffalo? I mean, are we like E.O. Wilson's ants now?
Mr. FOWLER: I have actually a very different take on this. So on the one hand, we're saying there are all these people out there, that some of who you don't know and have never met are going to have an influence on your life. But turn that on its head.
When you tell someone that they have an influence on people who are three degrees removed from them, you're telling them that they have an effect on, you know, 10 friends, their 100 friends of friends, their 1,000 friends of friends of friends, suddenly you're telling them that they're responsible not just for themselves but a whole host of people, some of whom they don't even know, and I think that a lot of people, the way they react to that sense of responsibility, is I'm going to actually try to work harder to exert my own will over my own life.
FLATOW: And have a positive influence on other people.
Mr. FOWLER: Yeah.
Mr. CHRISTAKIS: Yeah, I mean, in essence, actually, we run - we have this tension in the book. I mean, that is one of the ideas animating the book, this notion of free will, and we do actually talk about E.O. Wilson's work, and we do make the argument that in some sense it's possible to understand human society as a kind of super-organism and that in many ways these networks are living, breathing entities, which have a memory, which are able to have things flow through them, which survive and transmute, and these networks actually can be seen in some sense as a super-organism.
But just as James said, on the one hand while that would seemingly subvert the notion of free will, that we are just responding to the things that are happening around us, it also increases the importance of free will, makes it even more important that we think about how our actions are affecting others.
FLATOW: These are great thoughts, great topics. It's a terrific book. It's a great read. We've run out of time.
I want to thank Nicholas Christakis and James Fowler, author of "Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives." Thank you, gentlemen, for taking time to be with us today. Good luck on the book.
Mr. FOWLER: Thank you very much.
Mr. CHRISTAKIS: Thank you.
FLATOW: You're welcome. Transcript provided by NPR, Copyright NPR.