Happiness is thus not merely a function of individual experience or choice; it is also a property of groups of people. Changes in individual happiness can ripple through social connections and create large-scale patterns in the network, giving rise to clusters of happy and unhappy individuals. Since our work was published, similar results on the spread of happiness have been observed in a sample of ten thousand rural Chinese villagers.28 Although we could not observe what causes happiness to spread, a variety of mechanisms are conceivable. Happy people may share their good fortune (e.g., by being pragmatically helpful or financially generous to others), change their behavior toward others (e.g., by being nicer or less hostile), or merely exude an emotion that is contagious. Being surrounded by happy people might have beneficial biological effects too. But whatever the mechanism, it seems clear that we need to change the way we think about happiness and other emotions.
Life on the Hedonic Treadmill
We all know people who are hedonists; they can never get enough of the good life. In fact, lasting happiness is difficult to achieve because people are on a “hedonic treadmill.” Although a change in a person’s circumstances may cause him to be happier (e.g., finding a partner, winning the lottery) or sadder (e.g., losing a job, becoming paralyzed), a broad body of research has shown that people tend to return to their previous level of happiness after such events.29 In fact, studies of lottery winners and spinal cord injury patients reveal that after a year or two, they are often no more happy or sad than the rest of us. Our surprise at this observation stems in part from our inability to anticipate that some things will not change. Lottery winners still have annoying relatives, and paralyzed patients can still fall in love. As psychologist Daniel Gilbert has shown, we tend to focus on only the most salient part of a situation when we are thinking about things that might befall us.30 Moreover, we overlook our ability to adapt to circumstances. So, a person trying to become happier is like someone walking up a downward-moving escalator. Although the effort to climb up and become happier is helpful, it is counteracted by the process of adaptation that forces one back to one’s original state.
Many people try to overcome this problem by intentionally engaging in activities to improve their happiness. We might change our behavior by exercising regularly or by trying to be kind to others or even by avoiding a long commute (which has been shown to be particularly deleterious to happiness). We might change our attitude by pausing to count our blessings or thinking about experiences in the most positive light (as Tibetan monks do). We might also devote effort to causes we find meaningful or strive to achieve important personal goals. Indeed, there is reason to suspect that a sustained effort to engage in such happiness-producing activities might help us progress up the downward-moving escalator.
But in spite of these efforts, 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. In fact, like other personality traits, personal happiness appears to be strongly influenced by our genes. Studies of identical and fraternal twins show that identical twins are significantly more likely to exhibit the same level of happiness than are fraternal twins or other siblings. 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 What we experience in life can, of course, change our moods for a period of time, but in most cases these changes are transitory.
What about the network spread of happiness? Does it obey this constraint, only making us happy for a while? Does the effect of having a friend become happy tend to wear off? In our study, we found that a person is 45 percent more likely to be happy if a friend became happy in the previous six months. In contrast, the effect is only 35 percent for friends who became happy within the previous year, and it disappears after longer periods of time. So, our friends’ happiness does have an effect on us, but it only lasts for about a year. Just as lottery winners get used to their newfound wealth, we get used to our friends being happy. But if different friends get happy at different points in time, they might give us a periodic boost, helping us to stay above our natural level of happiness.
Alone in the Crowd
If happiness can spread, at least for a while, what about other emotions? One feeling that directly concerns our social network is loneliness. In some sense, loneliness is the opposite of connection—it is the feeling of being disconnected. Work by 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 This often motivates most (but not all) people to redress their situation, suggesting that the function of loneliness is to promote reconnection (we will discuss the evolutionary purpose of loneliness in chapter 7).
Psychologists have identified the way that feelings of loneliness fit in with a broad set of other feelings and states, including self-esteem, anxiety, anger, sadness, optimism, and shyness. 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. This research has focused on the subjective perception of being alone, but feeling lonely is not the same thing. While studies have shown, unsurprisingly, that having a good friend can decrease loneliness, what has not previously been examined is the effect of the whole social network on our tendency to feel lonely even in a crowd.
Using the same network in which we studied happiness, we examined whether being alone was associated with feeling lonely and whether such feelings could spread.33 We found that real-world social connections do have an effect on how we feel. 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. Since 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. It is not clear why this is the case. Possibly, people in small families know they have a greater responsibility to spend time with one another since there are fewer people to take turns visiting. Or perhaps people in large families primarily feel close to a smaller core of their family, limiting the influence of additional connections. Regardless of the mechanism, it is clear that feelings of loneliness are much more closely tied to our networks of optional social connections than to those handed to us at birth.
Loneliness can actually shape the social network. 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, but they also tend to name fewer people as friends as well. What this means is that loneliness is both a cause and a consequence of becoming disconnected. Emotions and networks can reinforce each other and create a rich-get-richer cycle that rewards those with the most friends. People with few friends are more likely to become lonely, and this feeling then makes it less likely that they will attract or try to form new social ties.
Our study suggests that physical proximity matters as much for loneliness as it does for happiness. Friends and family who live nearby see each other more often, which should help decrease the likelihood that they feel lonely, but it also makes them more susceptible to one another’s feelings. For example, if a nearby friend has ten extra lonely days a year, it will increase the number of lonely days you experience by about three. If this person is a close friend, then the effect is stronger, and you’ll experience four extra days of loneliness. Loneliness also spreads between next-door neighbors, with ten extra days of loneliness