>> hinojosa: how much are we influenced by our friends? can happiness, obesity, and altruism really be socially infectious? a look at the surprising power of our social networks. internationally renowned physician and social scientist nicholas christakis. i'm maría hinojosa. this is one-on-one. dr. nicholas christakis, it's so nice to have you here on the show. >> it's nice to see you. >> hinojosa: so you wrote... you co-wrote this book. it's called connected: the surprising power ofour social networks and how they shape our lives. and it's a fascinating book because basically what you're saying is something that is really controversial, which is why the book has gotten a lot of attention, and therefore, you...

you're basically saying that our small little social networks, the personal networks, can determine so much about the rest of our lives. and when so many of us, at least in this country, are kind of made to believe that we can do this on our own, it's... you know, "pull yourself up by your bootstraps and you can do this," you're basically saying it really is true-- who you know and how they influence you has everything to do with what's going to happen with your life. >> okay, that's right, but the first thing i would emphasize is that people... okay, so most people, when they hear the words "social networks" nowadays think, you know, online networks like facebook and myspace and orkut, even, in brazil, and so forth. but actually, the kinds of social networks that james fowler, my coauthor, and i are interested in are the real old-fashioned social networks that human beings have been making actually for tens of thousands, hundreds of thousands of years. so i have friends, i have relatives, i have neighbors, i have colleagues and coworkers, and they in turn have relatives and friends and colleagues and coworkers, and as a result of that, we assemble ourselves into these very ornate, almost

baroque structures. they look like tangled christmas tree lights-- you know, these incredibly intricate structures where every light might be a person and the wires represent connections. and we'll assemble ourselves into these very expansive, elaborate, and complex structures, and then we proceed to live out our lives embedded in these structures, such that i'm connected to the people i know directly, and they are in turn connected to still other people, who are in turn connected to still other people. and as a result of this, i come to be indirectly connected to strangers, people i don't know, and it turns out that because things can spread in social networks, i can come to be affected by those people. so if your friend's friend, or your friend's friend's friend, for example, quit smoking or gains weight or becomes happy or acts kindly or votes, those types of behaviors that these strangers to us display or practice can ripple through the network and come to affect us. >> hinojosa: and so why is this important? what does it matter that we know

these things? because a lot of people are probably saying... well, yeah, there was this great shampoo commercial on a bazillion years ago. >> that's right. >> hinojosa: you know, "if you tell two friends and then they'll tell two friends," and then it just kind of pops up and the whole screen is filled with people who are now using this shampoo because you talked about it. >> that's right. >> hinojosa: so i think this is something that we know, but why is it important to understand it? >> okay, so we know it in two levels. first of all, most people are... would take it as self-evident that we are affected by our... the people to whom we're directly connected, but it is quite another thing to demonstrate that we are also affected by the people to whom we're indirectly connected. strangers to us can affect us. if i tell you your taste in clothes might depend on the taste in clothes that your friends have, or whether you quit smoking might be affected by whether your best friend quits, most people would accept that, although it's interesting to quantify that and to see to what extent is that the case. but if i were to tell you that actually, your taste in clothes or your propensity to quit smoking could be affected also by people that you don't know, then it becomes a little bit more interesting to be able to

demonstrate how that happens, first and second... >> hinojosa: but i'll tell you that my immediate reaction is just like, "i don't know how i feel about that." >> right, okay. >> hinojosa: i'm not so sure... i mean, i like this community feeling, but the fact that they actually may have an influence in determining my decisions? >> okay, good, so first... one little twig, and then we'll come back to that point. and the second thing is is that people are affected not only about... not only with respect to things like their taste in music or fashions, or things that people might think of as being kind of, um, phenomena or desires that are affected by others, but even in things that they might think of as very deeply personal, like their body size or their beliefs or their emotional state. so there are two moves here. first, we're saying that it's not just that you're affected by the people to whom you're directly connected, you're also affected by these other people that are strangers. and second, you're not just affected by these kind of routine things-- you think, "oh, what music i listen to"-- you're even affected when it comes to things like your emotions or your body size or things like that. and the reason that that's interesting, among several

reasons that that's interesting, is, as you're suggesting, it's a little creepy. it suggests that, you know... >> hinojosa: so you recognize the creepiness of it. >> i do recognize the creepiness, but i also want to say that it's not... we don't want to set up a kind of false dichotomy, like either we have free will or there's destiny, and, like, you know, we have no control over our lives. both are the case. and many people have read our work and said that it delivers a kind of whack to free will, that what our work does is it suggests that actually people are less in control of their own lives than they think. we're all part of this human superorganism-- part of this creature that is social networks-- and, as a result, we have less agency. we have less ability to determine our own destiny. and that's true. it's true that our work supports that claim, but equally it's true that our work lifts up the notion of free will, because what our work shows is that when you make a positive change in your life-- when you lose 20 pounds or you quit smoking or you become happy or you act kindly-- it doesn't just benefit you, and in fact, it doesn't just affect your friends, it affects dozens, hundreds, sometimes thousands of other

people. so these ripple effects go both ways; not only are you affected by others, but you affect others. >> hinojosa: so does that mean that, essentially, all of us have the capacity to be leaders? because, you know, for example, i go out and i do a lot of public speaking, and people who come then say, "wow, that's a fascinating story. i feel inspired." and one of the reasons why i love doing this is because when you know that you have actually inspired someone, another human being, to perhaps believe in themselves, it's an extraordinary thing. and what i like to say is that that means that everybody has the capacity to do that to somebody else. so, in a sense, you have the capacity to be a leader because you don't realize that if you do lose weight or you do quit smoking or you decide to run every day, that somewhere out there, somebody is going to feel that positive vibe and do the same thing. >> okay, so i think it's important that we distinguish different kinds of leadership and influence. so the kind of influence that

someone that is a public figure might have, or that gives a speech might have, is rather different than the kind of personal, interpersonal influence that we were talking about right now. so i might, for example, make a pronouncement or lecture to my students or write an article that is read widely in the newspaper, or send a tweet out to twitter followers, for example. >> hinojosa: because you do... you tweet, you twitter. >> well, we tweet from the book, "connected_book" is our tweet handle, but i don't personally tweet. i mean, i tweet, but i don't have, like, a nicholas christakis account. james and i share that account. but my point is that that's a different kind of interpersonal influence than the kind we're speaking about right now. so the kind that i'm interested in is the kind of face-to-face kind of way in which we affect each other. so it's the difference between the effect that, sort of, president obama has on his daughters versus the effect president obama has on all kids in the country, right? so the president can get up and everyone will pay attention to

him and he'll make some kind of pronouncement. he might have a weak effect over hundreds of thousands of people, or he could have a very strong, powerful, direct effect over someone he knows personally, face-to-face. and so both are important, but, um... i can actually illustrate this with a little analogy, okay? okay, so people have asked us how it is the case that there is... how there can be a kind of interpersonal influence when it comes to weight gain and obesity, for example, even though the models on the covers of magazines are as thin as they ever were. and that illustrates the difference between the two. so on the one hand, the thin model on the cover of a magazine has some kind of influence on us, but it's totally swamped by the weight gain amongst the people that we're directly connected to. so if all your friends are gaining weight, even if the ideal, let's say, as characterized by the, you know, cover models, is thin, still, that's not as powerful as the personal influence we experience by the people we know directly. >> hinojosa: so if somebody around you-- for example, a

coworker or two coworkers-- suddenly kind of go up in weight, like maybe ten or 15 pounds, you look at yourself and you're like, "hmm..." >> it's not so bad, right, it changes your ideas... >> hinojosa: "maybe it's not so bad, i could maybe do this." >> that's right, or the same kind of thing might happen... this is a bit more of an extreme example, but if you think about the behavior of people who are responsible for the care of prisoners. so we might have an ideal in this country that says we take care of prisoners, and we have a bill of rights, and we have habeas corpus, and we don't abuse prisoners. but if you're a prison guard and all the guards around you are abusing prisoners, even if you know the ideal, even if there are public figures that are making pronouncements, you're more affected by these personal connections than these abstract ideals. so both are important, but they're different phenomena. the public figure making a pronouncement can have some effect, maybe a weak effect over many people, but for a given individual, we're much more affected by these face-to-face interactions. and this is what i meant earlier when we said that we live out our lives in these complex

structures. to me, it's nothing short of amazing. we form, actually, something like ant colonies, but on a phenomenal scale. we have these little relationships and we make this very intricate pattern of ties, that as a result of that connects us to all these people we don't know personally and who nevertheless affect us. and james and i don't think it's a coincidence. we think that we as a species have actually evolved to do this, have evolved to have social networks, and have evolved to have particular kinds of social networks. >> hinojosa: all right, so a couple of things, because you brought up the issue of guards, and it's one that i've been looking actually very closely at, the issue of guards and people in detention. and you do say that what can happen is that there can be this, and i find you to be this eternal optimist. >> (laughs) yeah, yeah, yeah. >> hinojosa: we're happy for optimists, we're happy they're out there. but you also say, you know, other things that can spread in these social networks can be anger... >> yes. fascism. >> hinojosa: fascism. fear.

>> yes. >> hinojosa: violence. >> yes. >> hinojosa: suicide. >> yes. >> hinojosa: so help us out here. how do we... how do we go to the altruism, the losing weight, the quitting cigarettes, and that's what takes over all of this other negative stuff? >> okay, so the crucial thing to understand... there are a couple of crucial ideas here. the first idea is that, um, networks are agnostic. they will magnify whatever they are seeded with. the network itself doesn't give rise to these phenomena. the network is like a magnifying glass: something else impinges on the system and causes people... causes this thing to take off, and the network then magnifies it. so if you can imagine, for instance, that there's a person... a group of people on an isolated island in the pacific, there are 100 people, and they're all disconnected from each other, they're all living as hermits, and then all of a sudden a sailor washes up on the shore and he has an infection. if he interacts with the first person on the island, if the people on the island aren't interconnected, that first person gets sick and there's no epidemic. but if the people are interconnected into a network, all 100 of them will get sick.

but if the sailor hadn't washed up on the shore, nobody would have gotten sick. the network doesn't give rise to the epidemic. something seeds the network, and then because of the connections, instead of one person getting sick, 100 get sick. first point. second point, networks will magnify both good and bad things. so they will magnify fascism or drug use or deadly germs, but equally, they will magnify happiness or altruism or love and so forth. and the argument we make in the book is that on balance, the benefits of a connected life outweigh the costs. in fact, what happens as humans is that we pay a price for our interconnection. by being connected to you, i am subject to you potentially being violent, you infecting me with a germ, you making me unhappy. but also, simultaneously, i get all these benefits. and the argument is that overall, the benefits of interconnection outweigh the costs. >> hinojosa: so when you talk about living a connected life... you know, i feel like there's an increasing movement to want to be disconnected, but disconnected from our computers,

disconnected from those, you know, thousands of friends and followers on twitter and all that stuff. but to actually be disconnected... but you're saying it's okay to disconnect from those social networks on the internet. what you really want to focus on is on your social networks that are this, this... >> okay, so... >> hinojosa: i mean, everybody thinks, like, "i'm so connected," right? "i've got friends all over the world, i've got people following me, that's important." >> okay, so i want to draw, again, a distinction between these online interactions and and it's the latter that i'm especially interested in. and i also want to make sure that we don't confuse... >> hinojosa: i know you're interested in it, but you have to know, nicholas, there are a lot of people who think, like, "look, what matters now is exactly that. what's happening on your social media? i don't care about your friends at home, what's your social media?" >> first of all, these people are not your friends, okay? so these hundreds of friends... >> hinojosa: (laughs) oh, my god! >> they're not. at best, they're your acquaintances. and, in fact, i kind of resent the way facebook has co-opted this word "friend" and applied it to all of these individuals who are actually not your friends.

and, in fact, we've done some studies that show that amongst the, on average, 150 friends that people have on facebook, across the half billion people that are on facebook, actually only about five or six of them are your real friends. most of these people are not your friends any more than you might have a couple of real neighbors where you live, but you have many "neighbors" in your community, and those other neighbors don't really affect you, but your immediate neighbors, or your real neighbors, might. now, i think that it's really important to understand the difference between these tenuous online interactions and the face-to-face interactions, first point. and second point, i think it's very important to, um, understand that the medium is not the relationship. so let me give you an example by this. if i could interview my great-grandmother and ask her, when she was a little girl in greece, when she was eight or ten, how many friends she had, she would say, "i had one best friend," you know, "maria. and there were four or five of us girls that were a really tight community of girls.

we always played together. i remember them really well," she would say to me. and if i could talk to my current daughter, who is 13, as i have, and ask her, "lena, tell me about your friendships?" she would say, "i have my best friend, takina, and i have two or three other girls, jessie and claire and suzie, that are my friends," okay? so here we have my daughter, who has a cell phone in her pocket, who can skype with her friends at night, who has all this technology, and yet something very fundamental hasn't changed. she has the same sense of a best friend and the same sense of a close set of friends. so the technology has evolved hugely in 100 years, but the human spirit hasn't changed. in fact, what we're arguing in the book is that there's something very deeply fundamental about human connection and about human influence that is so deep and fundamental that we can study it scientifically, that we can understand things about it that are not obvious, and that these things are not... do not change just because we have new technologies. >> hinojosa: so does that mean that, for example, across the

world, it's the same kind of thing? you know, that suddenly, you know, the group of bangladeshi girls who maybe are quite poor, but they go to school, they have the same thing. they have this friend and these, you know... and do you see that actually replicated across the world? >> there are... there's no doubt that human beings, i mean, vary cross-culturally tremendously, in all kinds of ways-- the way we dress, the languages we speak, the beliefs that we have, and so forth. but there are other aspects of our humanity that tend not to vary so much. and one of the things that james fowler and i are so interested in is the very deep and fundamental way that social network interactions and social influence is encoded. the sense in which there's something so fundamental about our social relationships that, even though the details will vary from place to place, actually the fundamental reality doesn't change. and, in fact, as we show in the book and as we argue elsewhere in other work we've done, there's a very fundamental... actually, there are sort of mathematical rules that describe

how human beings interact, and these rules, these mathematical descriptions, don't change much from place to place. it's true that if you go to some places, people will have slightly more friends than other places. it's true that in some places, people's friends will be more likely to know each other than in other places. it's true if you go to some countries, intergender friendships are not permitted. you know, in saudi arabia, it would be very uncommon for a male to identify an unrelated female as a personal friend, something which we wouldn't think of as so weird in our country, for example. so there's variation, there's no doubt, but we are much more united in our common humanity in this fact of having friends and in this fact of affecting each other than we are divided by the details and how these inter... these phenomena vary from place to place. >> hinojosa: all right, so if you are a very outgoing person and you enjoy the face-to-face and you do it well, then that's one particular kind of person. but what about those people who, you know, they have a hard time interacting, and face-to-face is

just difficult? >> yes, yes, that's right. >> hinojosa: and i feel like, you know, in your work you're saying, "look, if you're able to go and network with people, be face-to-face, which is so important in terms of the professional world"... what about the people who have a hard time just doing that? >> okay, so that's... so that's very important to emphasize as well, and what's fascinating to us is that, as you describe, people vary in their interest and ability to have social interactions, which also is very fascinating. we all have evolved to have what is known as genetic fixation. we have particular traits that we all have. two eyes, to pick a trivial example, for instance. we don't vary in the number of eyes we have-- that's a cartoon example, but just to pick one-- but we vary in how many friends we have, and we vary in our height, for instance. some people are shorter, some people are taller. and this variation, how many friends we have, we also believe has significance. we've quantified this a little bit. so, for instance, if you look at a random sample of americans and you ask them two very basic questions, "who do you spend

free time with?" and "who do you discuss important matters with?"-- which are standard, old questions that are asked in this field to identify who their social contacts are-- on average, people identify four- and-a-half such people. >> hinojosa: is that good? is that normal? >> that's typical. >> hinojosa: it's kind of stayed the same in terms of the united states? >> it has stayed the same across time. it tends not to vary cross-culturally. people, on average, have about four-and-a-half personal connections, people that they identify when you ask questions like this. and this would include their spouse, if they're married, or their significant other, a couple of... a best friend, a couple other friends, maybe a coworker, a minister... their personal connections. but it varies even in our country. so about five percent have nobody. five percent of americans will say there's nobody with whom they can discuss intimate or important matters with or spend free time with. and at the other tail of the distribution, about, i can't remember now, five or ten percent have eight people, so it varies. now, some of it is by choice. some of us are shy, we're not interested in interacting with others.

some of us are gregarious, as you mentioned, we have social butterflies who interact with lots of people, but on average it's about four and a half. and actually, we've done some work looking at this cross-culturally from place to place, and this is pretty consistent, actually, which also says something, i think, fundamental about human beings. >> hinojosa: what about inequality? okay, i mean, it's a big issue, but if we're all kind of connected, then shouldn't we... shouldn't questions of poverty already have kind of been, you know, alleviated a little bit because we all know someone and we want to help uplift people? i mean... >> okay, so i would have two answers to that question. first of all, muhammad yunus won the nobel prize for microfinance, this idea that we can make small loans to people in very poor countries and kind of improve their well-being, and one of his key insights was that even poor people have friends, and in fact, those friends... >> hinojosa: which was like, amazing, that's it's like a key insight that even poor people have friends. >> that's right.

>> hinojosa: and actually... and poor people will pay you back. >> that's right, and that the friendship connections have value. they're a kind of collateral. so you can monetize that collateral. so what you do is, you form a little consortium of people who come, let's say, with their friends, and you say, "you are all jointly responsible for the repayment of this loan." so the first point is that everybody has friends, even the poorest person has friends, and that also is kind of fascinating, and again, it goes back to the point we were discussing earlier about our common humanity. second, however, sort of as a related idea and in some ways opposite to what we just said, is this notion of inequality that you mentioned. so on the one hand, yes, it's true everyone has friends; on the other hand, we're accustomed in our society to thinking about inequality in terms of race, for example, black and white, or wealth, you know, rich and poor, or where you're located, urban or rural, for example. but when you take social networks seriously, you can begin to think about other kinds of inequality. for instance, who's in the middle of the network and who's on the edge of the network? who has many friends and who has few friends? who belongs to what clique?

what region of the network are you a part of, and how does that place you at risk for certain outcomes regardless of your own personal attributes? so, for instance, let's say you're a person that's situated in a network surrounded by unhappy people. maybe your friends are happy, but maybe their friends are unhappy, so you've got this shell of unhappy people that's around you. it might be the case that this puts you at risk for becoming unhappy in the future, and that this is a kind of inequality compared to someone else that's located somewhere else in the network. this is a kind of network inequality, a positional inequality, that has previously not gotten a lot of attention, but we think it's important. >> hinojosa: all right, so can i change my life if i decide... if i change my social network? if i basically say, "you know what? i'm going to move away from all of these really depressed, overweight people." >> so no, wait, that's not what we're recommending, to be very, very clear. >> hinojosa: no, no. >> okay, and so we've looked at this a little bit. okay, so this is a little complicated, but the gist of it is this... here's the way to encapsulate that idea. let's say for the sake of argument... okay, so there are two things happening in networks.

one is this notion of connection, how we're connected to other people, and the other is the notion of contagion, what's flowing through the network. two distinct phenomena. what's the architecture of the ties around you, and then, given those ties, what kinds of things are moving through the network? you could have many friends or few friends, for instance, or you could have many friends who are infected with a germ, and the germ is spreading towards you, or many friends who are not infected with a germ, and the germ isn't spreading towards you. >> hinojosa: okay. >> two different ideas: what's the pattern of ties and what's flowing across them? in the case that you put on the table, for instance, of obesity, you might think that it might be beneficial to you to cut the tie to someone that's gaining weight, and it might interrupt some kind of input... >> hinojosa: sounds brutal. >> yeah, it sounds brutal and it is brutal, because any benefit that accrued to you from cutting this tie would be counteracted by the cost you paid in losing a friend. so any benefit that accrued to you from interrupting the contagion is counteracted by the cost you pay by interrupting the connection. so these are distinct phenomena, so it's not always obvious what might happen.

now, if all your friends are armed robbers, i think i can recommend you should disconnect from them, but it's not so simple as this, first point. second point, this... in some way, what james and i are arguing is that there's something so fundamental about human social networks and so deeply embedded in us as a species and as individuals, that we cannot by sheer strength of will just change our networks. you know, we live out our... any more than i could suddenly wake up and decide, "you know what? i'm going to be a brazilian from now on. i'm going to move to sao paulo and that's where i'm going to live for the rest of my life." >> hinojosa: the economy's growing. >> yeah, exactly, "and i'm just going to have new friends there, i'm going to get a new house, i'm just going to move my life." no, i'm embedded, right, in a community, in a society, in a location. i have a home and i have connections and i have work and so forth. it's not easy to pick up and move, and it's the same with networks. you can't just suddenly remove yourself from these social ties and teleport yourself to another part of the network, because you're embedded, and this embeddedness matters. >> hinojosa: all right, well, let's stay with the embeddedness, and the final thing that we're going to leave our viewers with is... so, what

do we do? so what does one do? like, what... if one wants to improve one's life... >> right. >> hinojosa: have more networking possibilities, improve your profession, improve your career, or improve your social life. because i kind of feel like... i'm like, you can do certain things but you can't do certain things. so what do you want our audience to say? >> all right, so i would turn that on its head and i would quote john f. kennedy and i would say, "ask not what your country can do for you-- ask what you can do for your country." so instead of saying, "how can i," you know, um... >> hinojosa: benefit. >> yeah, benefit from it, instead say to myself, "oh, my goodness, if i make a positive change in my life, if i'm kind to others, if i quit smoking, if i make an effort to be a happier person, this doesn't just have benefits for me. it can benefit the people that i love and that i'm connected to and the people to whom they're connected to, and dozens, hundreds, sometimes thousands of other people can come to be affected by the changes that we make." >> hinojosa: i'm going to go home and be really happy. >> excellent, me too.

>> hinojosa: and it's going to infect everybody. >> excellent, me too. >> hinojosa: dr. nicholas christakis, thank you so much for being here. >> thank you, maria. thank you for having me. >> hinojosa: continue the conversation at wgbh.org/oneonone yowy

- [voiceover] funding for overheard with evan smith is provided in part by: mfi foundation. improving the quality of life within our community. also, by hillco partners. a texas government affairs consultancy. and by the alice kleberg reynolds foundation. - hi, i'm evan smith. he's a 2016 democratic presidential candidate who formerly served as the governor of maryland and the mayor of baltimore. he's martin o'malley. this is overheard. (upbeat music) (applause) - [voiceover] let's be honest, is this about the ability to learn or is this about the experience of not having been taught properly? how have you avoided what has befallen other nations in africa and-- - you could say that he'd made his own bed, but you caused him to sleep in it. you know, you saw a problem and over time took it on and-- let's start with the sizzle before we get to the steak. are you gonna run for president? i think i just got an f from you actually. (applause) (upbeat music)