Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler Flashcards
simplest social network of all: a pair of people, a dyad. 21
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
How did humans come together to accomplish what they could not do on their own? 39
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
if your friend’s friend’s friend gained weight, you gained weight. We discovered that if your friend’s friend’s friend stopped smoking, you stopped smoking. And we discovered that if your friend’s friend’s friend became happy, you became happy. 44
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A network of humans has a special kind of life of its own. 55
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we began to think of them as a kind of human superorganism. 61
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Just as brains can do things that no single neuron can do, so can social networks do things that no single person can do. 67
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
For decades, even centuries, serious human concerns, such as whether a person will live or die, be rich or poor, or act justly or unjustly, have been reduced to a debate about individual versus collective responsibility. 68
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Scientists, philosophers, and others who study society have generally divided into two camps: those who think individuals are in control of their destinies, and those who believe that social forces (ranging from a lack of good public education to the presence of a corrupt government) are responsible for what happens to us. 70
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
believe that our connections to other people matter most, 74
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
To know who we are, we must understand how we are connected. 77
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Notions of collective guilt and collective revenge that underlie cascades of violence seem strange only when we regard responsibility as a personal attribute. Yet in many settings, morality resides in groups rather than in individuals. 106
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Two-thirds of the acts of interpersonal violence in the United States are witnessed by third parties, and this fraction approaches three-fourths among young people.4 108
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
In the United States, 75 percent of all homicides involve people who knew each other, often intimately, prior to the murder. 116
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Social-network ties can—and, as we will see, usually do—convey benefits that are the very opposite of violence. 136
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Social networks spread happiness, generosity, and love. 144
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
If each person acts independently, then your house will surely be destroyed. Fortunately, this does not happen because a peculiar form of social organization is deployed: the bucket brigade. 154
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
It’s amazing to be able to increase the effectiveness of human beings by as much as an order of magnitude simply by arranging them differently. 161
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A group can be defined by an attribute (for example, women, Democrats, lawyers, long-distance runners) or as a specific collection of individuals to whom we can literally point (“those people, right over there, waiting to get into the concert”). 167
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A social network is altogether different. While a network, like a group, is a collection of people, it includes something more: a specific set of connections between people in the group. These ties, and the particular pattern of these ties, are often more important than the individual people themselves. They allow groups to do things that a disconnected collection of individuals cannot. 169
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A company of one hundred soldiers is typically organized into ten tightly interconnected squads of ten. 176
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The telephone tree also vastly reduces the number of steps it takes for information to flow among people in the group, minimizing the chance that the message will be degraded. 194
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
An article in the Los Angeles Times from 1957, for example, describes the use of a phone tree to mobilize amateur astronomers, as part of the “Moonwatch System” of the Smithsonian Astrophysical Observatory, to track American and Russian satellites.8 197
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A network community can be defined as a group of people who are much more connected to one another than they are to other groups of connected people found in other parts of the network. 214
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Four different ways to connect one hundred people. Each circle (“node”) represents a person, and each line (“tie”) a relationship between two people. Lines with arrows indicate a directed relationship; in the telephone tree, one person calls another. Otherwise, ties are mutual: in the bucket brigade, full and empty buckets travel in both directions; in military squads, the connections between the soldiers are all two-way. 218
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
a social network is an organized set of people that consists of two kinds of elements: human beings and the connections between them. 221
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
On average, each student is connected to six other close friends, but some students have only one friend, and others have many. 226
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
having better-connected friends literally moves you away from the edges and toward the center of a social network. 231
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
In this natural network of close friendships among 105 college students living in the same dormitory, each circle represents a student, and each line a mutual friendship. 236
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A network’s shape, also known as its structure or topology, is a basic property of the network. 241
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Visualization software tries to show this in two dimensions and to reveal the underlying topology by putting the most tangled buttons in the center and the least connected ones on the edges. 253
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
First, there is connection, which has to do with who is connected to whom. 262
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Second, there is contagion, which pertains to what, if anything, flows across the ties. 268
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
RULE 1: WE SHAPE OUR NETWORK 274
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
homophily, the conscious or unconscious tendency to associate with people who resemble us (the word literally means “love of being alike”). 275
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we also choose the structure of our networks in three important ways. First, we decide how many people we are connected to. 278
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Second, we influence how densely interconnected our friends and family are. 280
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
third, we control how central we are to the social network. 282
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
three thousand randomly chosen Americans. And we found that the average American has just four close social contacts, with most having between two and six. Sadly, 12 percent of Americans listed no one with whom they could discuss important matters or spend free time. At the other extreme, 5 percent of Americans had eight such people. 294
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Sociologist Peter Marsden has called this group of people that we all have a “core discussion network.” 298
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
a national sample of 1,531 Americans studied in the 1980s, he found that core-discussion-network size decreases as we age, that there is no overall difference between men and women in core-network size, and that those with a college degree have core networks that are nearly twice as large as those who did not finish high school.9 299
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
this relationship is transitive—the three people involved form a triangle. 306
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Those with high transitivity are usually deeply embedded within a single group, while those with low transitivity tend to make contact with people from several different groups who do not know one another, making them more likely to act as a bridge between different groups. 308
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
typical American, the probability that any two of your social contacts know each other is about 52 percent. 310
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
RULE 2: OUR NETWORK SHAPES US 322
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Our place in the network affects us in turn. A person who has no friends has a very different life than one who has many. 322
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Transitivity can affect everything from whether you find a sexual partner to whether you commit suicide. 333
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Being more central makes you more susceptible to whatever is flowing within the network. 342
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
your centrality affects everything from how much money you make to whether you will be happy. 346
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
RULE 3: OUR FRIENDS AFFECT US 347
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Students with studious roommates become more studious. 354
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
RULE 4: OUR FRIENDS’ FRIENDS’ FRIENDS AFFECT US 356
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
hyperdyadic spread, or the tendency of effects to spread from person to person to person, beyond an individual’s direct social ties. 363
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Psychologist Stanley Milgram’s famous sidewalk experiment illustrates the importance of reinforcement from multiple people.12 On two cold winter afternoons in New York City in 1968, Milgram observed the behavior of 1,424 pedestrians as they walked along a fifty-foot length of street. He positioned “stimulus crowds,” ranging in size from one to fifteen research assistants, on the sidewalk. On cue, these artificial crowds would stop and look up at a window on the sixth floor of a nearby building for precisely one minute. There was nothing interesting in the window, just another guy working for Milgram. The results were filmed, and assistants later counted the number of people who stopped or looked where the stimulus crowd was looking. While 4 percent of the pedestrians stopped alongside a “crowd” composed of a single individual looking up, 40 percent stopped when there were fifteen people in the stimulus crowd. Evidently, the decisions of passersby to copy a behavior were influenced by the size of the crowd exhibiting it. 382
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
While one person influenced 42 percent of passersby to look up, 86 percent of the passersby looked up if fifteen people were looking up. 391
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
a stimulus crowd of five people was able to induce almost as many passersby to look up as fifteen people did. 392
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
RULE 5: THE NETWORK HAS A LIFE OF ITS OWN 394
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
1986 World Cup in Mexico. In this phenomenon, originally called La Ola (“the wave”), 401
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
waves usually rolled in a clockwise direction and consistently moved at a speed of twenty “seats per second.”13 404
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
there is no central control of the movement of the group, but the group manifests a kind of collective intelligence that helps all within it to flee or deter predators. 413
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
This behavior does not reside within individual creatures but, rather, is a property of groups. 414
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the flock’s collective choice is better than an individual bird’s would be.14 416
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
social networks have emergent properties. Emergent properties are new attributes of a whole that arise from the interaction and interconnection of the parts. 419
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Stanley Milgram masterminded another, much more famous experiment showing that people are all connected to one another by an average of “six degrees of separation” 425
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
small-world effect originally characterized by de Sola Pool and Kochen, 431
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
in 2002, physicist-turned-sociologist Duncan Watts and his colleagues Peter Dodds and Roby Muhamad decided to replicate Milgram’s experiment on a global scale using e-mail as the mode by which people communicated.16 434
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
spread of influence in social networks obeys what we call the Three Degrees of Influence Rule. 443
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Everything we do or say tends to ripple through our network, having an impact on our friends (one degree), our friends’ friends (two degrees), and even our friends’ friends’ friends (three degrees). Our influence gradually dissipates and ceases to have a noticeable effect on people beyond the social frontier that lies at three degrees of separation. 443
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we are influenced by friends within three degrees but generally not by those beyond. 446
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
There are three possible reasons our influence is limited. First, like little waves spreading out from a stone dropped into a still pond, the influence we have on others may eventually peter out. 451
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
We call this the intrinsic-decay explanation. 456
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Second, influence may decline because of an unavoidable evolution in the network that makes the links beyond three degrees unstable. Ties in networks do not last forever. Friends stop being friends. 456
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
We call this the network-instability explanation. 461
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Third, evolutionary biology may play a part. As we will discuss in chapter 7, humans appear to have evolved in small groups in which everyone would have been connected to everyone else by three degrees or less. 462
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we may not be able to influence people four degrees removed from us because, in our hominid past, there was no one who was four degrees removed from us. We call this the evolutionary-purpose explanation. 465
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the observation that there are six degrees of separation between any two people applies to how connected we are, the observation that there are three degrees of influence applies to how contagious we are. 478
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
properties, connection and contagion, are the structure and function of social networks. They are the anatomy and physiology of the human superorganism. 480
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Social networks have value precisely because they can help us to achieve what we could not achieve on our own. 488
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
a social network is like a commonly owned forest: we all stand to benefit from it, but we also must work together to ensure it remains healthy and productive. 493
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
two different kinds of inequality in our society: situational inequality (some are better off socioeconomically) and positional inequality (some are better off in terms of where they are located in the network). 499
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
If we want to understand how society works, we need to fill in the missing links between individuals. 513
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
“endwara yokusheka,” which means simply, “the illness of laughing.” 539
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
emotions have a collective and not just an individual origin. How you feel depends on how those to whom you are closely and distantly connected feel. 543
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
First, we usually have a conscious awareness of our emotions: when we are happy, we know it. 546
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Second, emotions typically affect our physical state: we show how we feel on our faces, in our voices, even in our posture; 546
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Third, emotions are associated with specific neurophysiological activity; if you are shown a scary picture, the flow of blood to structures deep in your brain instantly changes. 548
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Finally, emotions are associated with visible behaviors, like laughing, crying, or shrieking.2 549
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Experiments have demonstrated that people can “catch” emotional states they observe in others over time frames ranging from seconds to weeks.3 550
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
When college freshmen are randomly assigned to live with mildly depressed roommates, they become increasingly depressed over a three-month period.4 551
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
When waiters are trained to provide “service with a smile,” their customers report feeling more satisfied, and they leave better tips.5 553
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Given the organization of early hominids into social groups, the spread of emotions served an evolutionarily adaptive purpose.6 Early humans had to rely on one another for survival. 559
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The development of emotions in humans, the display of emotions, and the ability to read the emotions of others helped coordinate group activity by three means: facilitating interpersonal bonds, synchronizing behavior, and communicating information. 563
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Emotions and emotional contagion probably first arose to facilitate mother-infant pair bonding and then evolved to extend to kin members and ultimately to nonkin members. 565
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
positive emotions may work especially well to increase group cohesiveness (“I’m happy; stay with me”) and that negative emotions may work well as communication devices (“I smell smoke; I’m scared”). 573
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Emotions may be a quicker way to convey information about the environment and its relative safety or danger than other forms of communication, and it seems certain that emotions preceded language. 574
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Emotions spread from person to person because of two features of human interaction: we are biologically hardwired to mimic others outwardly, and in mimicking their outward displays, we come to adopt their inward states. 583
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Nowhere do we show our emotions more than on our faces. 587
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Humans have an extraordinary knack for detecting even small changes in facial expressions. This ability is localized in a particular area of the brain and can even be lost, a condition tongue-twistingly known as prosopagnosia. 597
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Even as early as 1759, it was apparent to founding economist and philosopher Adam Smith that conscious thought was one way we could feel for others and hence feel like others: “Though our brother is upon the rack… by the imagination we place ourselves in his situation, we conceive ourselves enduring all the same torments, we enter as it were into his body, and become in some measure the same person with him, and thence form some idea of his sensations, and even feel something which, though weaker in degree, is not altogether unlike them.”8 600
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
People imitate the facial expressions of others, then, as a direct result, they come to feel as others do. This is called affective afference, or the facial-feedback theory, 606
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
telephone operators are trained to smile when they work, even though the person at the other end of the line cannot see them. This theory also explains why it helps to smile when your heart is breaking. 609
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
emotions (and behaviors) contagious may be the so-called mirror neuron system in the human brain.9 Our brains practice doing actions we merely observe in others, as if we were doing them ourselves. 611
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we are always poised to feel what others feel and to do what others do. 620
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
laughter like the Bukoba outbreak. 627
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
When emotions spread from person to person and affect large numbers of people, it is now called mass psychogenic illness (MPI) rather than the old-fashioned and more poetic epidemic hysteria. 627
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A relatively recent example of MPI occurred at the Warren County High School in McMinnville, Tennessee. At the time, the school had 1,825 students and 140 staff members. On November 12, 1998, a teacher believed she smelled gasoline, which caused her to complain of headache, shortness of breath, dizziness, and nausea. Seeing her response, some of her students soon developed similar symptoms. 644
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The diagnosis was epidemic hysteria. 666
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The astonishing reality is that our own anxiety makes us sick, but so does the anxiety of others. 671
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The problem is that while public health professionals often suspect that an outbreak is psychogenic, they feel they have no choice but to conduct an unreasonably thorough investigation because of intense anxiety in the community. 673
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
One systematic review of cases of epidemic hysteria identified seventy outbreaks that occurred between 1973 and 1993 and found that 50 percent of them took place in schools, 40 percent in small towns and factories, and only 10 percent in other settings.15 The outbreaks usually involved at least thirty people, and often hundreds. Most outbreaks lasted less than two weeks, but 20 percent lasted more than a month. 680
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
For some reason that is not well understood, smells, both real and imagined, are frequent triggers of modern outbreaks of MPI. This may have to do with the well-established connection between olfaction and emotions. 703
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
smell and emotion are both regulated by a part of the brain called the orbitofrontal cortex.17 704
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Proust phenomenon, after the author who described a poignant memory inspired by the scent of a cookie. 708
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
MPI is a pathological phenomenon, but it takes advantage of a nonpathological process that is fundamental in humans, namely, the tendency to mimic the emotional state of others. 746
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
experience-sampling method. This method uses a series of alerts (such as signals sent to a beeper or cell phone) at unexpected times to prompt subjects to document their feelings, thoughts, and actions while they are experiencing them.23 751
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
There was a strong association between a player’s own happiness and the happiness of his teammates, independent of the state of the game; further, when a player’s teammates were happier, the team’s performance improved. 768
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
unhappy people cluster with unhappy people in the network, and happy people cluster with happy people. Second, unhappy people seem more peripheral: they are much more likely to appear at the end of a chain of social relationships or at the edge of the network.26 787
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
a person is about 15 percent more likely to be happy if a directly connected person (at one degree of separation) is happy. 793
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The happiness effect for people at two degrees of separation (the friend of a friend) is 10 percent, and for people at three degrees of separation (the friend of a friend of a friend), it is about 6 percent. At four degrees of separation, the effect peters out. 794
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
having happy friends and relatives appears to be a more effective predictor of happiness than earning more money. 800
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
having more friends and relatives is much more likely to put a smile on your face than having more cash.27 804
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we are hardwired to seek out social relationships, so it is not surprising that we feel pleasure or reward when we spend time with friends and family. Second, friends and relatives make us susceptible to emotional contagion, so our friends’ emotional states affect our own (the third rule of social networks). 807
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
each happy friend a person has increases that person’s probability of being happy by about 9 percent. Each unhappy friend decreases it by 7 percent. 810
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
having more friends is not enough—having more happy friends is the key to our own emotional well-being. 814
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
When we measured the centrality of each person in the social network, we found that people with more friends of friends were also more likely to be happy. 817
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the more friends your friends have (regardless of their emotional state), the more likely you are to be happy. 819
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
So having a wide social circle can make you happy, but being happy does not necessarily widen your social circle. Being located in the middle of the network leads to happiness rather than the other way around. The structure of your network and your location in it matter. 823
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
when a friend who lives less than a mile away becomes happy, it can increase the probability that you are happy by 25 percent. In contrast, the happiness of a friend who lives more than a mile away has no effect. 829
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A happy sibling who lives less than a mile away increases your chance of happiness by 14 percent, but more distant siblings have no significant effect. 832
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the importance of proximity among people whose emotions influence each other, and the impact of immediate neighbors suggests that the spread of happiness may depend as much on frequent face-to-face interaction as on deep personal connections. 834
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
each of us tends to stay put in a particular long-term disposition; we appear to have a set point for personal happiness that is not easy to change. 860
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
personal happiness appears to be strongly influenced by our genes. 862
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Behavior geneticists have used these studies to estimate just how much genes matter, and their best guess is that long-term happiness depends 50 percent on a person’s genetic set point, 10 percent on their circumstances (e.g., where they live, how rich they are, how healthy they are), and 40 percent on what they choose to think and do.31 863
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
In some sense, loneliness is the opposite of connection—it is the feeling of being disconnected. 874
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
psychologist John Cacioppo has shown that loneliness is a complex set of feelings experienced by people whose core needs for intimacy and social connection are not met.32 875
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Psychological research suggests that feelings of loneliness occur when there is a discrepancy between our desire for connection to others and the actual connections we have. 879
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
People with more friends are less likely to experience loneliness. Each extra friend reduces by about two days the number of days we feel lonely each year. 885
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
on average (in our data) people feel lonely forty-eight days per year, having a couple of extra friends makes you about 10 percent less lonely than other people. Interestingly, the number of family members has no effect at all. 886
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
feelings of loneliness are much more closely tied to our networks of optional social connections than to those handed to us at birth. 890
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
People who feel lonely all the time will lose about 8 percent of their friends, on average, over two to four years. Lonely people tend to attract fewer friends, 892
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
loneliness is both a cause and a consequence of becoming disconnected. 893
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
loneliness spreads three degrees, just like happiness. 905
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
you are about 52 percent more likely to be lonely if a person you are directly connected to (at one degree of separation) is lonely. The effect for people at two degrees of separation is 25 percent, and for people at three degrees of separation, it is about 15 percent. At four degrees of separation the effect disappears, in keeping with the Three Degrees of Influence Rule. 907
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
If we are concerned about combating the feeling of loneliness in our society, we should aggressively target the people at the periphery with interventions to repair their social networks. By helping them, we can create a protective barrier against loneliness that will keep the whole network from unraveling. 913
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
there is one emotion central to human experience that we have not yet considered and that is key to understanding social connection: love. 922
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
anthropologist Helen Fisher has argued, the sensibility of being in love may be broken down into lust, love, and attachment, all of which likely served evolutionary purposes.34 924
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we lose sight of the extraordinary degree to which our choice of a partner is determined by our surroundings and, in particular, by our social network. 978
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Roughly 68 percent of the people in the study met their spouses after being introduced by someone they knew, while only 32 percent met via “self-introduction.” 991
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Even for short-term sexual partners like one-night stands, 53 percent were introduced by someone else. 992
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
people ask family members for introductions to possible marriage partners and rely on their own resources to meet short-term partners. 1001
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
from 1914 until 1960, 15 to 20 percent of people reported meeting their future spouses in the neighborhood, but by 1984 this percentage was down to 3 percent, reflecting the decline of geographically based social ties 1035
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Gone are the days of the girl next door. People increasingly meet their partners through (offline and online) social networks that are much less constrained by geography than they used to be. 1045
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the best way to search your network is to look beyond your direct connections but not so far away that you no longer have anything in common with your contacts. 1054
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
homogamy, or the tendency of like to marry like (just as homophily is the tendency of like to befriend like). 1068
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
72 percent of marriages exhibit homophily (based on a summary measure involving several traits), compared to 53 to 60 percent for other types of sexual relationships.10 1074
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
people often care more about their relative standing in the world than their absolute standing. 1098
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
economist John Kenneth Galbraith argued in 1958, many consumer demands arise not from innate needs but from social pressures.11 1099
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
People assess how well they are doing not so much by how much money they make or how much stuff they consume but, rather, by how much they make and consume compared to other people they know. 1100
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
are comparing themselves to those from whom they are three degrees removed. They do not compare themselves to strangers. Instead, they seem intent on impressing people they know. 1102
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
people reported that they would rather work at a company where their salary was $33,000 but everyone else earned $30,000 than at another, otherwise identical company where their salary was $35,000 but everyone else earned $38,000.12 1103
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
We would rather be big fish in a small pond than bigger fish in an ocean filled with whales. 1106
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A: Your physical attractiveness is 6; others average 4. B: Your physical attractiveness is 8; others average 10. Overall, 75 percent of people preferred being in situation A than in situation B. 1109
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
relative standing is important if it has what is known as an instrumental payoff: a more appealing physique than others is a means to an end. 1116
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
“I don’t need to outrun the bear; I just need to outrun you.” 1121
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the networks in which we are embedded function as reference groups, which is a social scientist’s way of saying “pond.” 1137
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
comparative effects (how we or others evaluate ourselves), influence effects (the way others dictate our behaviors and attitudes), or both.15 1139
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Having unattractive social contacts may make us feel superior (comparison) but may also make us take worse care of ourselves (influence). These two effects may work at cross-purposes in our quest to find a partner. 1140
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
There is thus a kind of unconscious social contagion in perceptions of attractiveness from one woman to another. 1163
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Daniel Gilbert has shown that a woman can do a better job of predicting how much she will enjoy a date with a man by asking the previous woman who dated him what he is like than by knowing all about the man.20 1168
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
College-age women were more likely to rate a man as attractive if shown a photograph of him surrounded by four women than if shown a photograph of him alone. But college-age men were less likely to rate a woman as attractive if she was shown surrounded by four men than if she was shown alone. 1177
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
sociologists Peter Bearman, Richard Udry, Barbara Entwisle, and Kathleen Harris, designed and launched an ongoing, nationwide social-network study of American adolescents in 1994. Known as the Add Health study, 1190
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
girls with a close relationship with their fathers were less likely to become sexually active.22 1201
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the number of friends, the age and gender of those friends, and their academic performance all affect the onset of sexual activity.23 1202
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
In a small number of “open” schools, where most opposite-sex friendships and romantic ties occur with individuals outside the school, more pledgers indeed meant delayed sexual debut. Surprisingly, though, in “closed” schools, where most ties occur inside the school, more pledgers meant a greater likelihood of sexual debut. These findings suggest that the pledge movement is an identity movement and not solely about abstaining from sex. 1211
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
if pledging becomes the norm, the psychological benefits of a unique identity are diminished, and the effect is lost. 1215
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
It’s not just the pledge itself that constrains behavior; it’s whether the pledge confers a unique status. 1216
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Adolescents who believe that their peers would look favorably on being sexually active are more likely to have casual, nonromantic sex.26 1219
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
decisions about how many children to have and whether to use contraception spread across social ties.30 1229
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the health benefits of marriage, and, conversely, the adverse health consequences of never marrying or of becoming widowed. As Farr 1260
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
married people seemed healthier due to a selection bias. Unhealthy people were less likely to get married, and healthy people were more likely to get married. 1275
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
which came first, health or marriage? Nineteenth-century observers could not tell. Scientific confusion persisted for a hundred years until the 1960s, 1282
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
mortality rate was 40 percent higher than expected for the first six months after a spouse’s death and then returned to the expected rate shortly thereafter. 1287
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
evidence that the risk of heart attack rises immediately after the death of a spouse.35 Something about being connected to a spouse affects our bodies and our minds. 1307
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
three explanations—homogamy, confounding, and a true causal effect—are 1309
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
being married adds seven years to a man’s life and two years to a woman’s life—better benefits than most medical treatments.36 1318
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The emotional support spouses provide has numerous biological and psychological benefits. Being near a familiar person—even 1324
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Spouses provide social support to each other and connect each other to the broader social network of friends, neighbors, and relatives. 1326
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the main way marriage is helpful to the health of men is by providing them with social support and connection, via their wives, to the broader social world. Equally important, married men abandon what have been called “stupid bachelor tricks.”40 1333
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
process of social control, with wives modifying their husbands’ health behaviors, appears to be crucial to how men’s health improves with marriage. 1337
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Conversely, the main way that marriage improves the health and longevity of women is much simpler: married women are richer. 1338
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
that perhaps this is just the age-old story of “trading sex for money”: women give men intimacy and a sense of belonging, and men give women cash. 1340
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
When men get married, they experience a sharp and substantial decline in their risk of death (the prompt elimination of stupid bachelor tricks). Women, on the other hand, do not derive an immediate health benefit. 1348
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
When a wife dies, the husband’s risk of death rises abruptly and dramatically, so that men who lose their wives are between 30 percent and 100 percent more likely to die during the first year of widowhood. 1351
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
when men die, the thing they brought to the marriage that had the greatest impact on their spouse’s health, namely money, is still around—in the form of assets such as a house and a pension. Conversely, when women die, the thing they brought to a marriage that most affected their partner’s health, namely, emotional support, a connection to others, and a well-run home, disappears. 1361
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Marriage to a younger woman is good for a man whereas marriage to a younger man is not good for a woman. 1372
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the bigger the age difference (up to certain limits) between an older husband and a younger wife, the better for both parties when it comes to the health benefits of marriage.42 1373
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
white couples suffer a widowhood effect, but black couples do not. 1385
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
men married to black women did not experience a widowhood effect, whereas men married to white women did, regardless of the man’s own race.44 But how could a wife’s race affect her husband’s mortality during widowhood? 1389
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the difference in marriage benefits between women and men is very likely to be a consequence of the greater ability of women to keep their spouses connected. 1397
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The tendency to have several kinds of relationships (and sometimes many kinds of relationships with the same person) is called multiplexity. 1409
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A person’s risk of illness depends not merely on his own behavior and actions but on the behavior and actions of others, some of whom may be quite distant in the network. 1477
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
They cannot meaningfully influence the overall shape of the network, even though it certainly influences them 1499
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
No one is interested in the battle for the bronze medal at the Olympics, and nobody wants to hook up with their ex-lover’s lover’s ex-lover. 1509
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the more paths that connect you to other people in your network, the more susceptible you are to what flows within it. 1534
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
whites with many partners tend to have sex with other whites with many partners, and whites with few partners tend to have sex with whites with few partners. This keeps STDs in the core of active white partners. On the other hand, blacks with many partners have sex with other blacks with many and few partners. Hence, STDs spread more widely through the black population. 1545
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
safe-sex campaigns would be most effective if messages were directed at high-activity members (the cores, or hubs, of the networks) rather than targeted equally to all members of a community. 1551
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
focus on the architecture of a person’s social network, namely their structural position rather than their socioeconomic position. 1553
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Studies of social networks are showing that people are placed at risk not so much because of who they are but because of who they know—that is, where they are in the network and what is going on around them. 1555
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
people randomly assigned to be seated near strangers who eat a lot wind up doing the same, and the effect can be so subconscious that it has been called “mindless eating.”13 It seems that we just can’t help imitating others. 1587
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the word epidemic has two meanings. First, it means that there is a higher-than-usual prevalence of a condition. Second, it connotes contagion, suggesting that something is spreading rapidly. 1593
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
From 1990 to 2000, the percentage of obese people in the United States increased from 21 percent to 33 percent, and fully 66 percent of Americans are now overweight or obese. 1597
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Framingham Heart Study that has been ongoing in Framingham, Massachusetts, just west of Boston, since 1948. 1605
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Three Degrees of Influence Rule: 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. 1623
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
If a mutual friend becomes obese, it nearly triples a person’s risk of becoming obese. 1646
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
mutual friends are twice as influential as the friends people name who do not name them back. 1646
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
people are not influenced at all by others who name them as friends if they do not name them back. 1647
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the obesity epidemic does not have a patient zero; it is not a unicentric epidemic but a multicentric epidemic. 1666
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we now know that obesity is contagious. Since the publication of our study, we and three other independent teams have identified obesity contagion in other populations.15 1676
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
social critic Eric Hoffer once opined, “When people are free to do as they please, they usually imitate each other.” 1681
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Behavioral imitation can be either conscious or subconscious. 1685
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
when we see someone eat or run, our mirror neurons fire in the same part of the brain that would be activated if we ourselves were eating or running. It is as if our brains practice doing something that we have merely been watching. 1685
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
It is deeply rooted in our biological capacity for empathy and even morality, and it is connected to our origins as a social species, 1690
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
What spreads from person to person is what social scientists call a norm, which is a shared expectation about what is appropriate.17 1694
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
there can be a concordance of norms even if there is not a concordance of behaviors. 1704
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
obesity can spread even between socially close people who are very far apart geographically. 1708
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Norms can spread even if they do not affect a person’s behavior. Some people can be carriers of an idea without themselves exhibiting the behavior related to the idea. 1715
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
people detect and imitate local network norms about the acceptability of weight gain when our society as a whole still appears to privilege thinness? 1722
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
People see images of ideal body types in the media, but they are less influenced by such images—by this ideology—than they are by the actions and the appearance of the very real people to whom they are actually connected. 1725
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Ellen Goodman put it: “Professional anorexics such as Kate Moss, Calista Flockhart, and Victoria Beckham may present an incredibly shrinking ideal. But in real life we measure ourselves against our friends. Inch for inch.”18 1726
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Over the past forty years, smoking among adults has decreased from 45 percent to 21 percent of the population. 1740
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
There is a kind of synchrony in time and space when it comes to smoking cessation that resembles the flocking of birds or schooling of fish. Whole interconnected groups of smokers, who may not even know one another, quit together at roughly the same time, as if a wave of opposition to smoking were spreading through the population. 1747
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Decisions to quit smoking are not solely made by isolated individuals; rather, they reflect the choices made by groups of individuals connected to one another both directly and indirectly. 1750
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
as more and more people quit smoking over time, the smokers were forced to the periphery of their networks, just as they are now forced outdoors to smoke, even in the freezing cold. And it’s not just that they became less popular; they also tended to be friends with people who were less popular, which helped to speed up the dramatic increase in their social isolation. 1761
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
More connections within groups (in what is known as a concentrated network) can reinforce a behavior in the groups, but more connections between groups (in what is known as an integrated network) can open up a group to new behaviors and to behavioral change—for better or for worse. 1767
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
drinking appears to be greatly influenced by women. If a woman starts drinking heavily, both her male and her female friends are likely to follow suit. But when a man starts drinking more, he has much less effect on either his female friends or his male buddies down at the bar. 1778
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Not all social ties are equal. 1789
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
friends affect each other more than spouses do in the spread of obesity. 1789
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
more susceptible to influence by peers of the same sex than by peers of the opposite sex. 1791
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Harvard students were 8.3 percent more likely to get a flu shot if an additional 10 percent of their friends got a flu shot.22 1794
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The rate of lower back pain among working-age people is 10 percent in the United States, 36 percent in the United Kingdom, 62 percent in Germany, 45 percent in Denmark, and 22 percent in Hong Kong.24 1804
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
suggest that back pain can be seen as a culture-bound syndrome—a disease recognized in one society but not others, 1807
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Koro, a condition that is seen in some Asian countries and that involves intense anxiety arising from the conviction among afflicted men that their penises are receding into their bodies and might disappear, and that they might die as a result. The treatment consists of asking trusted family members to hold the penis twenty-four hours a day for some number of days to prevent it from receding. 1809
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
one study of sororities, women who were binge eaters actually became more popular and moved to the center of the social network, 1823
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Suicide contagion is perhaps the most devastating illustration of the power of social networks. 1827
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
suicide contagion occurs almost exclusively among the young. Adults older than twenty-four show little, if any, excess likelihood of killing themselves if someone they know has done so or if they simply read about a suicide in the paper.31 1873
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Internet suicide clubs in Japan, the United Kingdom, the United States, and many other developed nations, which are formed by two or more strangers for the purpose of killing themselves together or simultaneously).34 1922
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
having a friend who committed suicide increased the likelihood of suicidal ideation. 1926
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
1997 study found that 13 percent of American adolescents seriously considered suicide in the previous year, and 4 percent of adolescents actually attempted it.37 Moreover, 20 percent of adolescents reported having a friend who had attempted suicide in the previous year. From 1950 to 1990, the rate of successful suicide for people fifteen to twenty-four years of age increased from 4.5 to 13.5 per 100,000.38 1940
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
connections that can make us happy can also make us suicidal. 1947
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
people are more influenced by the people to whom they are directly tied than by imaginary connections to celebrities. 1978
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
identify the hubs in the social network (who might or might not be poor or smokers) and target them with smoking-cessation messages. Early results with such approaches have documented success in fostering better diets and safer sex.43 1983
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
In addition to focusing, for example, on whether people are poor or where they live, we might focus on who they know and what kinds of networks they inhabit. 1988
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Computer models of the obesity epidemic confirm that targeting central individuals in the network to encourage healthy weight can be an effective strategy, whether these central people are overweight or not.45 1999
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
at both the individual and the population levels, it is more effective for you to lose weight with friends of friends than with friends. The problem is this: If you attempt to lose weight with your friends, you might succeed, but this tiny cluster of you and your friends is surrounded by a large group of people exerting pressure to gain weight again. In all likelihood, both you and your friends will thus regain weight. 2002
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A choice informed by network science could be seven hundred times more effective and efficient.47 2018
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Kelly and O’Grada found that social networks were the single most important factor in explaining the closure of accounts during both panics, even more so than the size of the accounts or the length of time they had been opened. Thus, financial panics may result from the spread of emotions or information from person to person. 2101
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
individually rational behavior can lead to communally irrational behavior. We are all capable of thinking with our heads, but our hearts keep in touch with the crowd, and sometimes this leads us to disaster. 2108
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
in 1998, a database consultant from Brookline, Massachusetts, named Hank Eskin figured out a way to satisfy this curiosity. He started a website called Where’s George? (WheresGeorge.com). 2122
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
As of 2008, more than 133 million bills had been tracked, with a total value of over $729 million (the site accepts all denominations). One user, Gary Wattsburg, has entered almost a million of those bills himself, but the majority of the bills are reported by newcomers to the website. 2129
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
it took more than three years for the plague to move from the southern part of Europe to its northern reaches, with an average speed of movement of two or three miles a day.11 2159
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
one of the people involved in the 2003 SARS outbreak carried the infection eight thousand miles (from China to Canada) in a single day! 2161
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The overall pattern indicates two important features of human interaction. First, bills stay much closer to home for a much longer time than previous models of human movement had predicted. Our regular routine involves straying little and spending cash locally. Yet, when bills do jump from one place to another, the distance they jump is typically much longer than previous models of human behavior had predicted. 2183
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the jumps follow a mathematical pattern poetically called a Lévy flight, after the French mathematician Paul Pierre Lévy. 2186
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The random walk (left) shows five thousand steps of equal length in a random pattern of movement. In contrast, the Lévy flight (right) shows five thousand steps of varying length, sometimes with a “flight,” in a random pattern of movement. 2193
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
markets tend to oscillate near a given price for a while and then jump to a new one. 2215
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Human social networks thus have economic moods. 2238
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The economic boom in the 1890s in Boston and New York gave rise to the decade’s moniker “the gay nineties,” and we use equally evocative expressions when we speak of economic downturns as “panics” and “depressions.” 2239
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
“Vox Populi” (Latin for “voice of the people”), a 1907 article in Nature by polymath statistician Francis Galton.15 Galton visited the West of England Fat Stock and Poultry Exhibition, a county fair where there was a contest to guess the weight of a fattened ox. Participants had to pay six cents to guess, and the closest guesses won prizes. Galton managed to acquire the cards on which people had made their guesses, and he showed that most guesses were quite bad. However, when he ordered them from the lowest guess to the highest guess, he found that the median guess (1207 pounds) was extremely close to the actual weight of the ox (1198 pounds). Galton concluded, to his own surprise, that democratic decision making might not be as bad as previously thought. 2246
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
When faced with the challenge of identifying the correct weight of the ox, most individuals would get it wrong, but the group as a whole could get it right. 2252
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
compared market predictions with what actually happens, and they have shown that election markets predict outcomes better than other available methods, such as polling.16 2259
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
economists will point to markets like these to emphasize the triumph of the invisible hand, it is important to note that they are, in fact, special cases of group activities. In the fattened ox example, individual guesses were made independently. 2264
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Whether groups of people are able to reach a correct decision about something (the value of a product, the number of jelly beans in a jar, the weight of an ox) depends on whether decisions are made at the same time or sequentially. 2274
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
present in this community than in others nearby. The people in Tigua Loma had a problem. They didn’t talk to one another. 2314
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Strong ties may bind individuals together into groups, but weak ties bind groups together into the larger society 2347
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
“Prior to switching employers, how often did you see the person who helped you get the new job?” He found that only 17 percent responded “often,” while 55 percent said “occasionally”; the remaining 28 percent said “rarely.” Most workers found jobs via old college friends, past workmates, or previous employers. 2351
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
most of his subjects had acquired their jobs by (nearly) relying on the kindness of strangers. These were distant friends or friends of friends who passed their names to an employer or who passed information about jobs to the prospective employee. 2357
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
We might trust socially distant people less, but the information and contacts they have may be intrinsically more valuable because we cannot access them ourselves. 2366
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
people who have many weak ties will be frequently sought out for advice or offered opportunities in exchange for their information or access. In other words, people who act as bridges between groups can become central to the overall network and so are more likely to be rewarded financially and otherwise. 2367
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Wealthy individuals and big businesses shape their networks according to their financial and economic goals, and in turn, the shape of their networks has a big impact on whether they can achieve those goals. The good ol’ boys circle together and take care of their own. 2379
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Although today corporations rarely seal deals through intermarriage, they do share executives on their boards of directors. 2398
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
real-world interactions are often based on personal relationships between businesses that are embedded (strongly connected) in stable networks of trust and reciprocity. 2414
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
too much embeddedness can be a bad thing. An unconditional commitment to a particular business partner (a strong tie) can be disastrous if it causes a firm to completely ignore opportunities with other firms (weak ties). Thus, there is a trade-off 2419
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
building stable relationships with a certain group of partners and being willing to leave those relationships when changes in the market cause them to lose viability. It is important to have a mix of strong and weak ties, 2421
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
small-world networks is that they exhibit two important features: low average path length (people can easily reach others in the network through a small number of intermediaries, as Stanley Milgram’s Nebraska mail experiment illustrated) and high transitivity (most of a person’s friends are friends with one another). 2431
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
sweet spot that combines the diversity of new team members with the stability of previously formed relationships. 2440
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Breakthroughs are created in collaborative circles, and networks can amplify talent 2448
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Using citation as a measure of quality, Uzzi found that, on average, team efforts were judged to be better and more important science than efforts by individuals. 2454
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
“thirty-foot rule.” This rule states that people collaborate only with others within thirty feet of them. 2456
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
physical distance is becoming less of a constraint on scientific collaboration. 2459
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
small differences in the overall patterns of connection in the network can matter a great deal to the performance of the group. 2481
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
those with the most neighbors were able to drive the entire network to their preferred color. The investigators called this the minority-power effect. A small group of influentially positioned individuals can consistently get their way. 2498
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
although social networks may help us do what we could not do on our own, they also often give more power to people who are well connected. 2501
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
those with the most connections often reap the highest rewards. 2502
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Social networks help distribute risk and help groups cope more effectively with unexpected events 2526
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Yunus: “A sense of intergroup and intragroup competition also encourages each member to be an achiever.”33 2535
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
women are much more likely than men to invest in improving the lives of children via schooling and improved health services. Women are also more likely to invest in their husbands than men are in their wives. 2538
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Obama succeeded because these “working men and women” felt connected. 2575
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Many have commented on Obama’s remarkable ability to connect with voters, but even more impressive was his ability to connect voters to each other. 2577
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Dean’s campaign raised a lot of money but failed to mobilize supporters because they were not yet connected to one another. 2583
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Hughes built the social networking site My.BarackObama.com, which logged 1.5 million accounts at its peak. 2586
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Rationally speaking, each vote doesn’t count. The reason we vote, it turns out, has a lot to do with our embeddedness in groups and with the power of our social networks. 2603
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The closest was an election for the representative for New York’s 36th congressional district in 1910, when the Democratic candidate won by a single vote, 20,685 to 20,684. However, a subsequent recount in that election found a mathematical error that greatly increased the margin, meaning there are actually no examples of single-vote wins. 2649
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
How much would you hand over to be the kingmaker, the one person who chooses who runs the country for the next four years? One dollar? Ten dollars? One million dollars? When undergraduates answer this question, they usually give amounts of less than $10, 2665
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
A large body of evidence suggests that a single decision to vote in fact increases the likelihood that others will vote. 2705
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
when you decide to vote it also increases the chance that your friends, family, and coworkers will vote.10 2706
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
social connections may be the key to solving the voting puzzle. 2710
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the media does not reach the masses directly. Instead, a group of “opinion leaders” usually acts as an intermediary, filtering and interpreting the media for their friends and family who pay less attention to politics. 2731
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Several election studies show that we typically talk to only a few people about politics; in one study in which people were asked to name their “discussion partners,” about 70 percent reported fewer than five (on any topic).14 2753
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
if you vote, then it increases the likelihood that your friends’ friends vote as well. 2767
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
If you knew you could get lots of people to support your favorite candidate just by voting, you would probably be more likely to do it than if you thought your vote would get canceled out by a mix of people from the Left and Right. 2781
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
in ideologically polarized environments, the incentive to vote might be magnified by the number of like-minded individuals you could motivate to go to the polls. 2782
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the total number of people voting had virtually no effect on how far the cascades would spread in our computer model. 2795
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
we discovered that turnout cascades are primarily local phenomena, occurring in small parts of the population within a few degrees of separation from each individual. 2797
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the power of one individual to influence many is limited by the effect of competing waves of influence that emanate from everyone else in the network. 2798
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Putnam argues that highly clustered network ties improve information flow and increase reciprocity at a societal level because everyone is looking out for everyone else. In other words, more tightly knit connections are better for society. However, our work shows that, at a certain point, networks can become so transitive that norms and information simply circulate within groups rather than traveling between them. 2816
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
democratic citizens work best in “small worlds” where some of our friends know one another and others do not. 2820
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The big surprise, however, was in the behavior of the people who did not answer the door. As it turns out, the other person in the household was about 6 percent more likely to vote. In other words, 60 percent of the effect on the person who answered the door was passed on to the person who did not answer the door. 2829
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
many of our friends already know one another, which means the effect might bounce around between the same people and never reach others who are socially distant from us. 2846
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Instead of each of us having only one vote, we effectively have several and are therefore much more likely to have an influence on the outcome of an election. 2851
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Typically, about 20 to 30 percent of the people who say they voted in an election actually did not. 2860
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
politicians tend to manipulate their networks for political advantage. 2885
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
bills with many cosponsors (sometimes called “Mom and Apple Pie” bills by political scientists) are frequently supported by legislators who had no contact with the sponsor. 2961
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the best-connected representatives were able to garner ten more votes than average (out of 435 representatives), while the best-connected senators were able to garner sixteen more (out of 100 senators). 3004
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
if a bill is introduced by a person in the middle of the network, it would pass; but if the same bill were introduced by someone just outside of the middle, it would fail. Connectedness matters. 3007
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
But Keith was in greater danger of being voted out of the competition, and so he said to Tina, “I need this one,” and she willingly dropped into the water. 3165
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
I knew that for the good of our team, I had to let Keith win.” 3167
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Colby had chosen friendship over what seemed like certain victory. 3174
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Many people questioned Colby’s decision and claimed that he had miscalculated. But another plausible interpretation is that friendship and loyalty had trumped self-interest. 3176
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Like ants, bees, penguins, wolves, dolphins, and chimpanzees, human beings are social animals, living in close proximity to one another in groups. 3185
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Our embeddedness in social networks means that we must cooperate with others, judge their intentions, and influence or be influenced by them. 3190
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
humans don’t just live in groups, we live in networks. 3192
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
some species exhibit bucket-brigade behavior because it is an efficient adaptation to their environment; consider ants that pass food items from one worker to another, for example.2 3204
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Among early hominids, individuals who lived in social networks that enabled a group to acquire more food or to fend off attackers were more likely to survive and reproduce. As a result, over a long period of time, the individuals who naturally formed networks or who had specific traits conducive to forming particular kinds of networks would have had a selective advantage and might eventually have made up the largest part of the population. 3229
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
This is the puzzle of cooperation and altruism: people who are willing to help others should be, it might seem, less likely to survive than people who care only about themselves. 3239
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
cooperators who are willing to pay a personal cost to help a group of people are less likely to survive than free riders who do not pay a personal cost but benefit from the group’s activities. 3240
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
when humans learned to hunt large game hundreds of thousands of years ago, this gave a fitness advantage to the groups that knew how to do it. But if it is risky to take down a mastodon, why not let someone else do it? If you are the most selfish person in your group, then presumably you would be more likely to survive. 3242
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Ian McEwan, in Enduring Love, provides a vivid illustration of the problem of cooperation. A helium balloon is hovering near the ground in a green English field in strong winds. Curled up inside the basket is a frightened boy, and outside, hanging to a rope, is his grandfather, desperately trying to control the balloon before it is blown away. 3245
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
“enacted morality’s ancient, irresolvable dilemma: us, or me.”3 3254
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The good news is that people very often ignore their selfish tendencies when interacting with people to whom they are connected. 3255
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
evolutionary theory to whether it makes sense to help other people would be incorrect. Selfishness does not always pay. If it did, we would all be selfish. 3259
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Tina might have given up because she knew she would be competing with Keith in future challenges and would need his help. Evolutionary theorists call this direct reciprocity. If you have several opportunities to cooperate with the same person, one way to get that person to help you is to promise future cooperation. 3261
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
scientist Robert Axelrod showed that a cooperative strategy called “tit for tat” often is more effective than always cooperating or always being selfish.4 3264
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the first time you meet a selfish person you will cooperate with him but he won’t cooperate with you. You learned your lesson, and you will copy him in any future interaction, but that first meeting means he is a little more likely to do better since he got something from you on the very first interaction. 3270
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
what if they could choose not to interact? Rather than attempting to cooperate and risking being taken advantage of, a person could fend for herself. In other words, she could sever her connections to others in the network. Hauert called the people who adopt this strategy “loners.” 3276
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
in a world full of loners it is easy for cooperation to evolve because there are no people to take advantage of the cooperators that appear. 3279
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The loners fend for themselves, and the cooperators form networks with other cooperators. Soon, the cooperators take over the population because they always do better together than the loners. 3280
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
But once the world is full of cooperators, it is very easy for free riders to evolve and enjoy the fruits of cooperation without contributing 3281
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
cooperation can emerge because we can do more together than we can apart. But because of the free-rider problem, cooperation is not guaranteed to succeed. 3284
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
To deal with free riders, another type of person is needed: punishers. People everywhere feel the desire to enforce social norms they see being violated. 3285
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Cooperators connect to others in order to create more; free riders connect in order to leach off those who create; and punishers connect in order to drive away free riders. 3289
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
showed that small groups of interconnected, interacting cooperators and punishers could coevolve in a world of people who otherwise keep to themselves, and this pushes the whole population toward higher overall levels of cooperation and connection.7 3294
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the population was frequently in transition, meaning that we might expect to find different proportions of individuals of different types at any given moment. 3298
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
the model predicted two things: some people will cooperate, and others will not; and some people will be well connected to the social network, and others—the loners—will not. 3301
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The standard way of thinking about human beings in economics is that every person makes a decision without considering the interests of others (except insofar as the interests of others impinge on one’s own). 3304
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
incentive compatible: I scratch your back because I think you are going to scratch mine. 3306
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The expression Homo economicus, a slightly tongue-in-cheek construction, was first used at least one hundred years ago to describe a vision of our species as one that relies on self-interest to obtain the maximum personal good at the lowest possible cost. 3310
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
in 1836, philosopher John Stuart Mill was already propounding a model of “economic man” who “inevitably does that by which he may obtain the greatest amount of necessaries, conveniences, and luxuries, with the smallest quantity of labour and physical self-denial with which they can be obtained.”9 3312
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Implicit in this vision is that people are lazy and greedy but also rational and self-interested and self-directed. Such a model leaves no room for altruism. 3314
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Homo dictyous (from the Latin homo for “human” and the Greek dicty for “net”), or “network man,” 3317
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
This perspective allows our motivations to depart from pure self-interest. Because we are connected to others, and because we have evolved to care about others, we take the well-being of others into account when we make choices about what to do. Moreover, by stressing our embeddedness, this perspective allows us to formally include in our understanding of people’s desires a critical source: the desires of those around them. 3318
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
some of our tastes may be for things that are made more desirable when others desire them. 3325
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
In 1982, a group of economists developed a simple but clever experiment called the “ultimatum game” in which two players bargain over $10 given to them by the experimenter.10 3331
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
economists found that subjects frequently rejected low offers. Offers of $2 were rejected about half the time, and lower offers were rejected even more frequently. 3340
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
The most common offer was an exact fifty-fifty split, and, on average, the first player earned a little bit more than the second player, but not much more because rejected offers caused both players to lose everything. 3342
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
a new so-called dictator game 3348
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
In this game, the first player is given $10 and allowed to divide it between herself and the second player any way she likes. But now the second player can do nothing. 3348
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
economists expected that the first player would keep everything, and many did. But many more did not. The average first player gave away about $2 to the second player. The results of this extremely simple experiment were difficult to explain if we thought of behavior as being driven purely by self-interest. People were literally taking money out of their own pockets and giving it to anonymous strangers. 3350
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
Some people care only about themselves. But the majority of us take other peoples’ well-being and interests into account. 3357
Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler
