Connected: The Amazing Power of Social Networks and How They Shape Our Lives

The locations and circumstances under which people meet partners have been changing over the past century. Our best data on this come from a study conducted in France. Looking across a broad range of venues where people meet spouses, including nightclubs, parties, schools, workplaces, holiday destinations, family gatherings, or simply “in the neighborhood,” the investigators traced the change across time. For example, 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 as a consequence of modernity and urbanization.

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Geography is even less important with the rise of the Internet. In 2006, one in nine American Internet-using adults—all told, about sixteen million people—reported using an online dating website or other site (such as Match.com, eHarmony.com, or the wonderfully named PlentyofFish.com, as well as countless others) to meet people.

(#litres_trial_promo) Of these “online daters,” 43 percent—or nearly seven million adults—have gone on actual, real-life dates with people they met online, and 17 percent of them—nearly three million adults—have entered long-term relationships or married their online dating partners, according to a systematic national survey.

(#litres_trial_promo) Conversely, 3 percent of Internet users who are married or in long-term committed relationships reported meeting their partners online, a number that will likely rise in the coming years.

(#litres_trial_promo) 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.

My Partner Is Just Like Me

With the decline in importance of meeting people in the neighborhood in recent years, people no longer search geographic space for partners. Nevertheless, they still search social space. Rather than going from house to house or town to town, we jump from person to person in search of the perfect mate. We see if anyone near us in our network (e.g., our friends, coworkers) would be a suitable partner, and if not, we look farther away (e.g., our friends’ friends, our coworkers’ siblings). And we often seek out circumstances, such as parties, that are likely to result in meeting friends of friends and people still farther away in our network.

We have “weak ties” to friends of friends and other sorts of people we do not know very well. But, as we will discuss in chapter 5 (#litres_trial_promo), these kinds of ties can be incredibly valuable for connecting us to people we do not know at all, thereby giving us a much greater pool of people to choose from. So 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. A friend’s friend or a friend’s friend’s friend may be just the person to introduce you to your future spouse.

Some societies have richly prescriptive procedures for partner search, and although they severely limit personal choice for the betrothed, they still exploit network connections. Such marriages are often arranged for legal or economic reasons rather than from a desire to find a suitable partner (in the Western sense), and they are common in the Middle East and Asia. In some cultural settings, customs prescribe that the prospective partners be introduced to each other, and the parents take an active role in vetting the family and the potential spouse. In other settings, however, the marriage is a settled matter from the first meeting, and no courtship is allowed. Across cultures, there is considerable variation in who the matchmakers are (parents, professionals, elders, clergy), what pressures the matchmakers can exert, what qualifications the spouses must have (reputation, wealth, caste, religion), and what sanctions can be imposed if the couple refuses (disinheritance, death).

These practices are not immutable, however, even in societies where arranged marriage was formerly the norm. For example, the percentage of women living in Chengdu in Sichuan, China, who had arranged marriages shrank from 68 percent of those married between 1933 and 1948 to 2 percent of those wed between 1977 and 1987.

(#litres_trial_promo) Nevertheless, social-network ties still remain crucial; 74 percent of respondents in Chengdu report that the primary network that connects young people to potential mates is friends and relatives in the same age group.

Regardless of what kind of network people use, whether real or virtual, the process of searching for a mate is usually driven by homogamy, or the tendency of like to marry like (just as homophily is the tendency of like to befriend like). People search for—or, in any case, find—partners they resemble (in terms of their attributes) and partners who are of comparable “quality.” The Chicago Sex Survey, for example, shows that the great majority of marriages exhibit homogamy on virtually all measured traits, ranging from age to education to ethnicity. Other studies show that spouses usually have the same health behaviors (like eating and smoking), the same level of attractiveness, and the same basic political ideology and partisan affiliation (with rare, notable exceptions like Clinton adviser James Carville and Republican strategist Mary Matalin). We would expect more homophily in long-term relationships and less in short-term relationships (one is less finicky when it comes to sexual partners than potential spouses), and to some extent this is indeed the case: 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.

(#litres_trial_promo) In addition, as we shall see, spouses also become more similar over time because they influence each other (for example, in political affiliation, smoking behavior, or happiness).

On the one hand, homogamy makes intuitive sense. People like being around others who are similar to them. Most people find it comforting to imagine that partners resemble each other because it gives them hope that they, too, will someday be happy in a warm and loving relationship with a kindred spirit. On the other hand, think about the odds of finding someone just like you. Personal ads are full of complex laundry lists that must be very difficult, if not impossible, to satisfy: Wanted: frisky, down-to-earth, nonsmoking, leftist Democrat salsa dancer who likes guns, Bollywood films, NASCAR races, Ouija boards, beach sunsets, Cosmopolitans, country drives, and triathlons.

Indeed, the uniqueness of each human being has implications for how many people out there are a perfect fit in this sense. The age-old debate about whether you have one soul mate or a million rests in part on how picky you are. But even if there are a million compatible people for you, that is just one of every six thousand people in the whole world. If you are choosing at random, you had better go on a lot of dates. The dispiritingly unromantic conclusion is that you will never, ever find Mr. or Ms. Right. Not without some help.

But the surprising power of social networks is that they bring likes together and serve up soul mates in the same room. Bigger and broader social networks yield more options for partners, facilitate the flow of information about suitable partners via friends and friends of friends, and provide for easier (more efficient, more accurate) searching. Hence, they yield “better” partners or spouses in the end. The odds of finding that soul mate just improved substantially.

Given the structure of social networks, our tendency to be introduced to our partners, and our innate comfort with people we resemble, it is not surprising that we generally wind up meeting, having sex with, and marrying people like ourselves. The choice of a partner is constrained by the same social forces that create network ties in the first place. Who we befriend, where we go to school, where we work—all these choices largely depend on our position in a given social network. No matter where people search, their network generally acts to bring similar people together. The fact that spouses are so often similar manifestly disproves the idea that people meet and choose their partners by chance.

Big Fish, Little Pond

American satirist H. L. Mencken famously observed that wealth is “any income that is at least one hundred dollars more per year than the income of one’s wife’s sister’s husband.” With this statement, he captured an idea that is well known to most people but strangely unpopular in the formal study of economics: namely, that people often care more about their relative standing in the world than their absolute standing. People are envious. They want what others have, and they want what others want. As economist John Kenneth Galbraith argued in 1958, many consumer demands arise not from innate needs but from social pressures.

(#litres_trial_promo) 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.

An essential truth in Mencken’s quip is that the two men 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. In a classic experiment investigating this phenomenon, most 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.

(#litres_trial_promo) Even though their absolute income is less at the first job, they think they would be happier working there than at the second. We would rather be big fish in a small pond than bigger fish in an ocean filled with whales.

Perhaps not surprisingly, this is also true of our desire to be attractive. In one creative experiment, respondents were asked which of the following two states they would rather be in:

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. For most people, their relative attractiveness was more important than their absolute attractiveness.

(#litres_trial_promo) We have repeated this experiment with Harvard undergraduates, and their responses were even more skewed: 93 percent preferred situation A, and 7 percent situation B. And, of course, any bridesmaid forced to wear an unflattering dress understands this point.

These results show that our preference for relative attractiveness is more extreme than our preference for relative income. People realize how crucial it is to have sex appeal if they are to have sex. And they realize how important it is to be more attractive than their prospective mate’s other choices. In other words, 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.

This preference for relative standing brings to mind another classic anecdote: Two friends are hiking in the woods and come to a river. They take off their shoes and clothes and go for a swim. As they come out of the water, they spot a hungry bear that immediately starts to run toward them. One of the men starts fleeing immediately, but the other pauses to put on his shoes. The first man screams at the second, “Why are you putting on your shoes? They won’t help you outrun the bear!” To which the second man calmly responds: “I don’t need to outrun the bear; I just need to outrun you.”

It is this same reasoning that drives ever-larger numbers of people to have plastic surgery and with greater frequency. Liposuction might yield a physical advantage for early adopters, but when everybody gets it done, the advantage goes away. As a result, people then demand other kinds of plastic surgery in a kind of silicone arms race. The breadth of services demanded explodes to parallel the spread of services through the network.

Competition for mates can actually be quite stressful. One investigation we conducted suggests that the higher the male-to-female ratio at a time when a man reaches his early twenties, the shorter his life. A man who is surrounded by other men has to work harder to find a partner, and this environment of elevated competition has long-term consequences for his health. In this regard, we are no different from a number of animal species. In one analysis, we examined the effect of the gender ratio in a sample of high-school seniors in Wisconsin in 1957—a total of 4,183 young men and 5,063 young women in 411 high schools. We found that men in high-school graduating classes with lopsided gender ratios (of more men) wound up with shorter life spans fifty years later. In another analysis of more than 7.6 million men from throughout the United States, we found that the availability of marriageable women again had a durable impact on men’s health, affecting their survival well into their later years.

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These results suggest that the people who surround us are not only a source of partners or of information about partners; they also are our chief competitors. As a result, the social network in which we find ourselves defines our prospects. It does so by defining whom we meet, by influencing our taste in what is deemed desirable in a partner, and, finally, by specifying how we are perceived by others and what competitive advantages and disadvantages we have. You don’t need to be the most beautiful or most wealthy person to get the most desirable partner; you just need to be more attractive than all the other women or men in your network. In short, the networks in which we are embedded function as reference groups, which is a social scientist’s way of saying “pond.”

In the 1950s, Robert K. Merton, a very influential social scientist, codified the basic ways that reference groups affect us: they can have comparative effects (how we or others evaluate ourselves), influence effects (the way others dictate our behaviors and attitudes), or both.

(#litres_trial_promo) 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.

For decades, reference groups have been seen as abstract categories: people often compare themselves to other “middle-class Americans” or other “members of their grade at school” or other “amateur soccer players.” But exciting advances in network science are now enabling us to map out exactly who these references group are for each person. Many people may be more attractive than we are, but our only real competitors are the people in our intended’s social network.

Everyone Else Is Doing It

People we know influence how we think and act when it comes to sex. To begin with, both friends and strangers affect our perceptions of a prospective partner’s attractiveness, consciously and unconsciously. These effects go beyond basic tendencies that men and women have to make judgments about appearance; for example, it has repeatedly been shown that men find women with low waist-to-hip ratios more attractive, and women value certain facial features in men. Until recently, most research on partner choice and assessments of attractiveness has focused on an individual’s independent preferences. Yet there are good biological and social reasons to suppose that perceptions of attractiveness can spread from person to person.

An experiment suggests how. First, investigators took pictures of men who were rated equally attractive by a group of women.

(#litres_trial_promo) Then, they presented pairs of pictures of two equally attractive men to another group of women, but between each pair of pictures, they inserted a picture of a woman who was “looking” at one of the men. This woman was smiling or had a neutral facial expression. The female subjects were much more likely to judge a man to be more attractive than his competitor if the woman interposed between the photos was smiling at him than if she was not.

In another study, a group of women again rated photographs of men for attractiveness. The photos were accompanied by short descriptions, and when the men were described as “married,” women’s ratings of them went up.

(#litres_trial_promo) In still another study, men in photographs with attractive female “girlfriends” were judged to be more attractive when the “girlfriend” was in the photo than when she was not. Having a plain “girlfriend,” however, did not enhance a man’s appeal as much.

(#litres_trial_promo) And, astoundingly, women’s preferences for men who are already attached may vary according to where the women are in their menstrual cycles. When they are in the fertile phase of the cycle, they have a relative preference for men who are already attached to other women.

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There is thus a kind of unconscious social contagion in perceptions of attractiveness from one woman to another. This makes perfect sense from an evolutionary perspective. Copying the preferences of other women may be an efficient strategy for deciding who is a desirable man when there is a cost (in terms of time or energy) in making this assessment or when it is otherwise hard to decide. While a woman can, with a glance, assess for herself various attributes of a man that might be associated with his genetic fitness (his appearance, his height, his dancing ability), other traits related to his suitability as a reproductive partner (his parenting ability, his likelihood of being sweet to his kids) can require more time and effort to evaluate. In those cases, the assessment of another woman can be very helpful. In fact, psychologist 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.

(#litres_trial_promo) This fact has been exploited for commercial purposes: there is a matchmaking website that only allows men to post if they are “recommended” by a former girlfriend.

In direct mate choice, you choose who you like, but in indirect mate choice of the sort we have been considering, you choose who others like. Indirect mate choice can even lead people to choose mates with characteristics that they did not previously care about. A slight preference by some women for men with tattoos, for example, can lead hordes of men to get tattoos and inspire other women to want men who have them.

Perhaps not surprisingly, men react differently to social information. While they clearly have shared norms about what is attractive in a woman, contextual cues in men can actually operate in the opposite way.

(#litres_trial_promo) 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. This makes evolutionary sense: when selecting mates, males tend to be less choosy than females and so are less concerned with the opinions of anyone else to begin with. But the presence of other men conveys information of a different sort, namely, that there might be time-consuming (and stressful) competition to secure the woman’s interest.