Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 1

simplest social network of all: a pair of people, a dyad. 21

Answer 1

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 2

How did humans come together to accomplish what they could not do on their own? 39

Answer 2

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 3

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

Answer 3

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 4

A network of humans has a special kind of life of its own. 55

Answer 4

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 5

we began to think of them as a kind of human superorganism. 61

Answer 5

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 6

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

Answer 6

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 7

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

Answer 7

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 8

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

Answer 8

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 9

believe that our connections to other people matter most, 74

Answer 9

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 10

To know who we are, we must understand how we are connected. 77

Answer 10

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 11

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

Answer 11

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 12

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

Answer 12

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 13

In the United States, 75 percent of all homicides involve people who knew each other, often intimately, prior to the murder. 116

Answer 13

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 14

Social-network ties can—and, as we will see, usually do—convey benefits that are the very opposite of violence. 136

Answer 14

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 15

Social networks spread happiness, generosity, and love. 144

Answer 15

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 16

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

Answer 16

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 17

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

Answer 17

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 18

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

Answer 18

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 19

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

Answer 19

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 20

A company of one hundred soldiers is typically organized into ten tightly interconnected squads of ten. 176

Answer 20

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 21

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

Answer 21

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 22

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

Answer 22

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 23

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

Answer 23

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 24

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

Answer 24

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 25

a social network is an organized set of people that consists of two kinds of elements: human beings and the connections between them. 221

Answer 25

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 26

On average, each student is connected to six other close friends, but some students have only one friend, and others have many. 226

Answer 26

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 27

having better-connected friends literally moves you away from the edges and toward the center of a social network. 231

Answer 27

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 28

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

Answer 28

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 29

A network’s shape, also known as its structure or topology, is a basic property of the network. 241

Answer 29

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 30

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

Answer 30

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 31

First, there is connection, which has to do with who is connected to whom. 262

Answer 31

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 32

Second, there is contagion, which pertains to what, if anything, flows across the ties. 268

Answer 32

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 33

RULE 1: WE SHAPE OUR NETWORK 274

Answer 33

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 34

homophily, the conscious or unconscious tendency to associate with people who resemble us (the word literally means “love of being alike”). 275

Answer 34

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 35

we also choose the structure of our networks in three important ways. First, we decide how many people we are connected to. 278

Answer 35

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 36

Second, we influence how densely interconnected our friends and family are. 280

Answer 36

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 37

third, we control how central we are to the social network. 282

Answer 37

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 38

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

Answer 38

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 39

Sociologist Peter Marsden has called this group of people that we all have a “core discussion network.” 298

Answer 39

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 40

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

Answer 40

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 41

this relationship is transitive—the three people involved form a triangle. 306

Answer 41

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 42

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

Answer 42

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 43

typical American, the probability that any two of your social contacts know each other is about 52 percent. 310

Answer 43

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 44

RULE 2: OUR NETWORK SHAPES US 322

Answer 44

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 45

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

Answer 45

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 46

Transitivity can affect everything from whether you find a sexual partner to whether you commit suicide. 333

Answer 46

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 47

Being more central makes you more susceptible to whatever is flowing within the network. 342

Answer 47

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 48

your centrality affects everything from how much money you make to whether you will be happy. 346

Answer 48

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 49

RULE 3: OUR FRIENDS AFFECT US 347

Answer 49

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 50

Students with studious roommates become more studious. 354

Answer 50

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 51

RULE 4: OUR FRIENDS’ FRIENDS’ FRIENDS AFFECT US 356

Answer 51

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 52

hyperdyadic spread, or the tendency of effects to spread from person to person to person, beyond an individual’s direct social ties. 363

Answer 52

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 53

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

Answer 53

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 54

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

Answer 54

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 55

a stimulus crowd of five people was able to induce almost as many passersby to look up as fifteen people did. 392

Answer 55

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 56

RULE 5: THE NETWORK HAS A LIFE OF ITS OWN 394

Answer 56

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 57

1986 World Cup in Mexico. In this phenomenon, originally called La Ola (“the wave”), 401

Answer 57

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 58

waves usually rolled in a clockwise direction and consistently moved at a speed of twenty “seats per second.”13 404

Answer 58

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 59

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

Answer 59

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 60

This behavior does not reside within individual creatures but, rather, is a property of groups. 414

Answer 60

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 61

the flock’s collective choice is better than an individual bird’s would be.14 416

Answer 61

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 62

social networks have emergent properties. Emergent properties are new attributes of a whole that arise from the interaction and interconnection of the parts. 419

Answer 62

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 63

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

Answer 63

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 64

small-world effect originally characterized by de Sola Pool and Kochen, 431

Answer 64

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 65

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

Answer 65

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 66

spread of influence in social networks obeys what we call the Three Degrees of Influence Rule. 443

Answer 66

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 67

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

Answer 67

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 68

we are influenced by friends within three degrees but generally not by those beyond. 446

Answer 68

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 69

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

Answer 69

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 70

We call this the intrinsic-decay explanation. 456

Answer 70

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 71

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

Answer 71

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 72

We call this the network-instability explanation. 461

Answer 72

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 73

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

Answer 73

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 74

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

Answer 74

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 75

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

Answer 75

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 76

properties, connection and contagion, are the structure and function of social networks. They are the anatomy and physiology of the human superorganism. 480

Answer 76

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 77

Social networks have value precisely because they can help us to achieve what we could not achieve on our own. 488

Answer 77

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 78

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

Answer 78

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 79

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

Answer 79

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 80

If we want to understand how society works, we need to fill in the missing links between individuals. 513

Answer 80

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 81

“endwara yokusheka,” which means simply, “the illness of laughing.” 539

Answer 81

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 82

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

Answer 82

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 83

First, we usually have a conscious awareness of our emotions: when we are happy, we know it. 546

Answer 83

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 84

Second, emotions typically affect our physical state: we show how we feel on our faces, in our voices, even in our posture; 546

Answer 84

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 85

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

Answer 85

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 86

Finally, emotions are associated with visible behaviors, like laughing, crying, or shrieking.2 549

Answer 86

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 87

Experiments have demonstrated that people can “catch” emotional states they observe in others over time frames ranging from seconds to weeks.3 550

Answer 87

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 88

When college freshmen are randomly assigned to live with mildly depressed roommates, they become increasingly depressed over a three-month period.4 551

Answer 88

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 89

When waiters are trained to provide “service with a smile,” their customers report feeling more satisfied, and they leave better tips.5 553

Answer 89

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 90

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

Answer 90

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 91

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

Answer 91

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 92

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

Answer 92

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 93

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

Answer 93

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 94

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

Answer 94

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 95

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

Answer 95

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 96

Nowhere do we show our emotions more than on our faces. 587

Answer 96

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 97

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

Answer 97

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 98

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

Answer 98

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 99

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

Answer 99

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 100

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

Answer 100

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 101

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

Answer 101

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 102

we are always poised to feel what others feel and to do what others do. 620

Answer 102

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 103

laughter like the Bukoba outbreak. 627

Answer 103

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 104

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

Answer 104

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 105

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

Answer 105

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 106

The diagnosis was epidemic hysteria. 666

Answer 106

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 107

The astonishing reality is that our own anxiety makes us sick, but so does the anxiety of others. 671

Answer 107

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 108

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

Answer 108

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 109

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

Answer 109

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 110

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

Answer 110

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 111

smell and emotion are both regulated by a part of the brain called the orbitofrontal cortex.17 704

Answer 111

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 112

Proust phenomenon, after the author who described a poignant memory inspired by the scent of a cookie. 708

Answer 112

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 113

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

Answer 113

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 114

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

Answer 114

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 115

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

Answer 115

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 116

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

Answer 116

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 117

a person is about 15 percent more likely to be happy if a directly connected person (at one degree of separation) is happy. 793

Answer 117

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 118

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

Answer 118

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 119

having happy friends and relatives appears to be a more effective predictor of happiness than earning more money. 800

Answer 119

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 120

having more friends and relatives is much more likely to put a smile on your face than having more cash.27 804

Answer 120

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 121

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

Answer 121

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 122

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

Answer 122

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 123

having more friends is not enough—having more happy friends is the key to our own emotional well-being. 814

Answer 123

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 124

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

Answer 124

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 125

the more friends your friends have (regardless of their emotional state), the more likely you are to be happy. 819

Answer 125

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 126

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

Answer 126

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 127

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

Answer 127

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 128

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

Answer 128

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 129

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

Answer 129

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 130

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

Answer 130

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 131

personal happiness appears to be strongly influenced by our genes. 862

Answer 131

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 132

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

Answer 132

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 133

In some sense, loneliness is the opposite of connection—it is the feeling of being disconnected. 874

Answer 133

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 134

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

Answer 134

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 135

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

Answer 135

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 136

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

Answer 136

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 137

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

Answer 137

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 138

feelings of loneliness are much more closely tied to our networks of optional social connections than to those handed to us at birth. 890

Answer 138

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 139

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

Answer 139

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 140

loneliness is both a cause and a consequence of becoming disconnected. 893

Answer 140

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 141

loneliness spreads three degrees, just like happiness. 905

Answer 141

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 142

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

Answer 142

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 143

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

Answer 143

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 144

there is one emotion central to human experience that we have not yet considered and that is key to understanding social connection: love. 922

Answer 144

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 145

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

Answer 145

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 146

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

Answer 146

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 147

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

Answer 147

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 148

Even for short-term sexual partners like one-night stands, 53 percent were introduced by someone else. 992

Answer 148

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 149

people ask family members for introductions to possible marriage partners and rely on their own resources to meet short-term partners. 1001

Answer 149

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 150

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

Answer 150

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 151

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

Answer 151

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 152

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

Answer 152

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 153

homogamy, or the tendency of like to marry like (just as homophily is the tendency of like to befriend like). 1068

Answer 153

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 154

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

Answer 154

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 155

people often care more about their relative standing in the world than their absolute standing. 1098

Answer 155

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 156

economist John Kenneth Galbraith argued in 1958, many consumer demands arise not from innate needs but from social pressures.11 1099

Answer 156

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 157

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

Answer 157

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 158

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

Answer 158

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 159

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

Answer 159

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 160

We would rather be big fish in a small pond than bigger fish in an ocean filled with whales. 1106

Answer 160

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 161

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

Answer 161

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 162

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

Answer 162

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 163

“I don’t need to outrun the bear; I just need to outrun you.” 1121

Answer 163

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 164

the networks in which we are embedded function as reference groups, which is a social scientist’s way of saying “pond.” 1137

Answer 164

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 165

comparative effects (how we or others evaluate ourselves), influence effects (the way others dictate our behaviors and attitudes), or both.15 1139

Answer 165

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 166

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

Answer 166

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 167

There is thus a kind of unconscious social contagion in perceptions of attractiveness from one woman to another. 1163

Answer 167

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 168

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

Answer 168

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 169

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

Answer 169

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 170

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

Answer 170

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 171

girls with a close relationship with their fathers were less likely to become sexually active.22 1201

Answer 171

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 172

the number of friends, the age and gender of those friends, and their academic performance all affect the onset of sexual activity.23 1202

Answer 172

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 173

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

Answer 173

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 174

if pledging becomes the norm, the psychological benefits of a unique identity are diminished, and the effect is lost. 1215

Answer 174

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 175

It’s not just the pledge itself that constrains behavior; it’s whether the pledge confers a unique status. 1216

Answer 175

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 176

Adolescents who believe that their peers would look favorably on being sexually active are more likely to have casual, nonromantic sex.26 1219

Answer 176

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 177

decisions about how many children to have and whether to use contraception spread across social ties.30 1229

Answer 177

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 178

the health benefits of marriage, and, conversely, the adverse health consequences of never marrying or of becoming widowed. As Farr 1260

Answer 178

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 179

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

Answer 179

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 180

which came first, health or marriage? Nineteenth-century observers could not tell. Scientific confusion persisted for a hundred years until the 1960s, 1282

Answer 180

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 181

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

Answer 181

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 182

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

Answer 182

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 183

three explanations—homogamy, confounding, and a true causal effect—are 1309

Answer 183

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 184

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

Answer 184

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 185

The emotional support spouses provide has numerous biological and psychological benefits. Being near a familiar person—even 1324

Answer 185

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 186

Spouses provide social support to each other and connect each other to the broader social network of friends, neighbors, and relatives. 1326

Answer 186

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 187

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

Answer 187

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 188

process of social control, with wives modifying their husbands’ health behaviors, appears to be crucial to how men’s health improves with marriage. 1337

Answer 188

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 189

Conversely, the main way that marriage improves the health and longevity of women is much simpler: married women are richer. 1338

Answer 189

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 190

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

Answer 190

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 191

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

Answer 191

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 192

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

Answer 192

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 193

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

Answer 193

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 194

Marriage to a younger woman is good for a man whereas marriage to a younger man is not good for a woman. 1372

Answer 194

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 195

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

Answer 195

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 196

white couples suffer a widowhood effect, but black couples do not. 1385

Answer 196

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 197

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

Answer 197

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 198

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

Answer 198

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 199

The tendency to have several kinds of relationships (and sometimes many kinds of relationships with the same person) is called multiplexity. 1409

Answer 199

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 200

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

Answer 200

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 201

They cannot meaningfully influence the overall shape of the network, even though it certainly influences them 1499

Answer 201

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 202

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

Answer 202

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 203

the more paths that connect you to other people in your network, the more susceptible you are to what flows within it. 1534

Answer 203

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 204

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

Answer 204

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 205

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

Answer 205

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 206

focus on the architecture of a person’s social network, namely their structural position rather than their socioeconomic position. 1553

Answer 206

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 207

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

Answer 207

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 208

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

Answer 208

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 209

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

Answer 209

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 210

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

Answer 210

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 211

Framingham Heart Study that has been ongoing in Framingham, Massachusetts, just west of Boston, since 1948. 1605

Answer 211

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 212

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

Answer 212

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 213

If a mutual friend becomes obese, it nearly triples a person’s risk of becoming obese. 1646

Answer 213

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 214

mutual friends are twice as influential as the friends people name who do not name them back. 1646

Answer 214

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 215

people are not influenced at all by others who name them as friends if they do not name them back. 1647

Answer 215

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 216

the obesity epidemic does not have a patient zero; it is not a unicentric epidemic but a multicentric epidemic. 1666

Answer 216

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 217

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

Answer 217

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 218

social critic Eric Hoffer once opined, “When people are free to do as they please, they usually imitate each other.” 1681

Answer 218

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 219

Behavioral imitation can be either conscious or subconscious. 1685

Answer 219

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 220

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

Answer 220

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 221

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

Answer 221

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 222

What spreads from person to person is what social scientists call a norm, which is a shared expectation about what is appropriate.17 1694

Answer 222

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 223

there can be a concordance of norms even if there is not a concordance of behaviors. 1704

Answer 223

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 224

obesity can spread even between socially close people who are very far apart geographically. 1708

Answer 224

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 225

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

Answer 225

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 226

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

Answer 226

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 227

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

Answer 227

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 228

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

Answer 228

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 229

Over the past forty years, smoking among adults has decreased from 45 percent to 21 percent of the population. 1740

Answer 229

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 230

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

Answer 230

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 231

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

Answer 231

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 232

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

Answer 232

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 233

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

Answer 233

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 234

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

Answer 234

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 235

Not all social ties are equal. 1789

Answer 235

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 236

friends affect each other more than spouses do in the spread of obesity. 1789

Answer 236

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 237

more susceptible to influence by peers of the same sex than by peers of the opposite sex. 1791

Answer 237

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 238

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

Answer 238

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 239

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

Answer 239

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 240

suggest that back pain can be seen as a culture-bound syndrome—a disease recognized in one society but not others, 1807

Answer 240

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 241

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

Answer 241

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 242

one study of sororities, women who were binge eaters actually became more popular and moved to the center of the social network, 1823

Answer 242

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 243

Suicide contagion is perhaps the most devastating illustration of the power of social networks. 1827

Answer 243

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 244

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

Answer 244

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 245

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

Answer 245

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 246

having a friend who committed suicide increased the likelihood of suicidal ideation. 1926

Answer 246

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 247

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

Answer 247

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 248

connections that can make us happy can also make us suicidal. 1947

Answer 248

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 249

people are more influenced by the people to whom they are directly tied than by imaginary connections to celebrities. 1978

Answer 249

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 250

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

Answer 250

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 251

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

Answer 251

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 252

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

Answer 252

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 253

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

Answer 253

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 254

A choice informed by network science could be seven hundred times more effective and efficient.47 2018

Answer 254

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 255

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

Answer 255

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 256

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

Answer 256

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 257

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

Answer 257

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 258

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

Answer 258

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 259

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

Answer 259

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 260

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

Answer 260

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 261

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

Answer 261

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 262

the jumps follow a mathematical pattern poetically called a Lévy flight, after the French mathematician Paul Pierre Lévy. 2186

Answer 262

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 263

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

Answer 263

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 264

markets tend to oscillate near a given price for a while and then jump to a new one. 2215

Answer 264

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 265

Human social networks thus have economic moods. 2238

Answer 265

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 266

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

Answer 266

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 267

“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

Answer 267

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 268

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

Answer 268

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 269

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

Answer 269

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 270

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

Answer 270

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 271

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

Answer 271

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 272

present in this community than in others nearby. The people in Tigua Loma had a problem. They didn’t talk to one another. 2314

Answer 272

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 273

Strong ties may bind individuals together into groups, but weak ties bind groups together into the larger society 2347

Answer 273

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 274

“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

Answer 274

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 275

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

Answer 275

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 276

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

Answer 276

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 277

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

Answer 277

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 278

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

Answer 278

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 279

Although today corporations rarely seal deals through intermarriage, they do share executives on their boards of directors. 2398

Answer 279

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 280

real-world interactions are often based on personal relationships between businesses that are embedded (strongly connected) in stable networks of trust and reciprocity. 2414

Answer 280

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 281

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

Answer 281

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 282

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

Answer 282

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 283

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

Answer 283

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 284

sweet spot that combines the diversity of new team members with the stability of previously formed relationships. 2440

Answer 284

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 285

Breakthroughs are created in collaborative circles, and networks can amplify talent 2448

Answer 285

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 286

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

Answer 286

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 287

“thirty-foot rule.” This rule states that people collaborate only with others within thirty feet of them. 2456

Answer 287

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 288

physical distance is becoming less of a constraint on scientific collaboration. 2459

Answer 288

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 289

small differences in the overall patterns of connection in the network can matter a great deal to the performance of the group. 2481

Answer 289

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 290

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

Answer 290

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 291

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

Answer 291

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 292

those with the most connections often reap the highest rewards. 2502

Answer 292

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 293

Social networks help distribute risk and help groups cope more effectively with unexpected events 2526

Answer 293

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 294

Yunus: “A sense of intergroup and intragroup competition also encourages each member to be an achiever.”33 2535

Answer 294

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 295

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

Answer 295

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 296

Obama succeeded because these “working men and women” felt connected. 2575

Answer 296

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 297

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

Answer 297

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 298

Dean’s campaign raised a lot of money but failed to mobilize supporters because they were not yet connected to one another. 2583

Answer 298

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 299

Hughes built the social networking site My.BarackObama.com, which logged 1.5 million accounts at its peak. 2586

Answer 299

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 300

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

Answer 300

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 301

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

Answer 301

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 302

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

Answer 302

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 303

A large body of evidence suggests that a single decision to vote in fact increases the likelihood that others will vote. 2705

Answer 303

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 304

when you decide to vote it also increases the chance that your friends, family, and coworkers will vote.10 2706

Answer 304

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 305

social connections may be the key to solving the voting puzzle. 2710

Answer 305

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 306

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

Answer 306

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 307

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

Answer 307

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 308

if you vote, then it increases the likelihood that your friends’ friends vote as well. 2767

Answer 308

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 309

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

Answer 309

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 310

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

Answer 310

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 311

the total number of people voting had virtually no effect on how far the cascades would spread in our computer model. 2795

Answer 311

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 312

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

Answer 312

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 313

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

Answer 313

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 314

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

Answer 314

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 315

democratic citizens work best in “small worlds” where some of our friends know one another and others do not. 2820

Answer 315

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 316

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

Answer 316

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 317

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

Answer 317

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 318

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

Answer 318

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 319

Typically, about 20 to 30 percent of the people who say they voted in an election actually did not. 2860

Answer 319

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 320

politicians tend to manipulate their networks for political advantage. 2885

Answer 320

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 321

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

Answer 321

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 322

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

Answer 322

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 323

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

Answer 323

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 324

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

Answer 324

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 325

I knew that for the good of our team, I had to let Keith win.” 3167

Answer 325

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 326

Colby had chosen friendship over what seemed like certain victory. 3174

Answer 326

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 327

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

Answer 327

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 328

Like ants, bees, penguins, wolves, dolphins, and chimpanzees, human beings are social animals, living in close proximity to one another in groups. 3185

Answer 328

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 329

Our embeddedness in social networks means that we must cooperate with others, judge their intentions, and influence or be influenced by them. 3190

Answer 329

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 330

humans don’t just live in groups, we live in networks. 3192

Answer 330

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 331

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

Answer 331

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 332

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

Answer 332

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 333

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

Answer 333

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 334

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

Answer 334

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 335

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

Answer 335

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 336

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

Answer 336

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 337

“enacted morality’s ancient, irresolvable dilemma: us, or me.”3 3254

Answer 337

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 338

The good news is that people very often ignore their selfish tendencies when interacting with people to whom they are connected. 3255

Answer 338

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 339

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

Answer 339

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 340

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

Answer 340

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 341

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

Answer 341

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 342

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

Answer 342

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 343

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

Answer 343

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 344

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

Answer 344

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 345

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

Answer 345

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 346

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

Answer 346

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 347

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

Answer 347

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 348

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

Answer 348

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 349

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

Answer 349

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 350

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

Answer 350

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 351

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

Answer 351

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 352

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

Answer 352

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 353

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

Answer 353

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 354

incentive compatible: I scratch your back because I think you are going to scratch mine. 3306

Answer 354

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 355

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

Answer 355

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 356

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

Answer 356

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 357

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

Answer 357

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 358

Homo dictyous (from the Latin homo for “human” and the Greek dicty for “net”), or “network man,” 3317

Answer 358

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 359

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

Answer 359

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 360

some of our tastes may be for things that are made more desirable when others desire them. 3325

Answer 360

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 361

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

Answer 361

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 362

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

Answer 362

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 363

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

Answer 363

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 364

a new so-called dictator game 3348

Answer 364

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 365

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

Answer 365

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 366

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

Answer 366

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler

Question 367

Some people care only about themselves. But the majority of us take other peoples’ well-being and interests into account. 3357

Answer 367

Connected: The Surprising Power of Our Social Networks by Nicholas A. Christakis, James H. Fowler