The desire to form social relationships is a fundamental part of human nature. We need to be part of stable, healthy bonds with family members, romantic partners, and friends in order to function normally. In fact, this very idea is central to why a subfield of psychology called social psychology first was developed.

It may seem obvious that people need other people, but appreciate that although we use the word need loosely in everyday language, in psychology the stakes are higher when we claim that something is a psychological need. It could be that close relationships are just nice, not necessary. (Consider: People may seek frequent, pleasant interactions with their computers, but they don’t need them.) What evidence is there that the motive to belong is inherent to our nature?

The Need to Belong Is Satiable

Biologically based needs work on the principle of homeostasis: You experience a deficiency (e.g., you’re hungry) that motivates thoughts and behaviors (you eat) until the need is satisfied (you’re full, stop eating). The same principle applies to close relationships. People do not need hundreds of relationships, just a few that are lasting and caring, and when they have them they are less motivated to form additional relationships. For example, although most college students have over 300 “friends” on Facebook, only a fraction of these are close friends or family (Manago et al., 2012). Intimate, face-to-face interactions might take place with only about six people (Wheeler & Nezlek, 1977).

The need to belong also resembles biologically based needs in that it can be satisfied in flexible ways. If your late-night hunger pangs motivate you to get up and search for cereal, and you discover that you are out of milk, you’ll find something else to eat. Similarly, when people are unable to satisfy their need to belong in their existing relationships, they turn to other relationships. For example, people in prison cope with the stressful separation from their biological family by forming substitute “families” with other prisoners (Burkhart, 1973).

All genetically inherited traits vary from person to person, and the need to belong is no different. People have different levels of this need and so differ in how many social relationships they want and how intimate they want them to be. Measures of need for affiliation (McAdams, 1989), need for intimacy (McAdams, 1980), need to belong (Leary et al., 2013), and attachment style (Hazan & Shaver, 1987) have been developed to capture this variability.

509

When the Need to Belong Is Satisfied, People Thrive

When people receive proper nutrition, shelter, sleep, and so on, they feel good psychologically and physically. In the same way, feeling connected to others promotes an individual’s mental and physical health. Compared with people who live more isolated lives, people who have pleasant interactions with a network of close friends, lovers, family members, and coworkers have higher self-esteem (Denissen et al., 2008; Leary & Baumeister, 2000), feel happier and more satisfied with their lives (Diener et al., 1999), and have better mental health (Kim & McKenry, 2002). Across different cultures, people who marry and stay married are happier overall than are those who are less committed to an intimate partnership (Diener et al., 2000). With regard to physical health, people who feel socially connected have stronger cardiovascular, immune, and endocrine systems, and they are less likely to die a premature death (Cacioppo & Patrick, 2008; House et al., 1988; Uchino, 2006; Uchino et al., 1996).

When the Need to Belong Is Chronically Unmet, Mental and Physical Health Decline

A hallmark of a need is that if it goes unsatisfied for a long time, people suffer negative consequences. It is in this respect that we see perhaps the strongest evidence for the claim that the need to belong qualifies as a true need. Hundreds of studies support the overall conclusion that when people are isolated for long periods of time, their mental and physical health deteriorates.

Many of these studies look at the experience of loneliness, or the feeling that one is deprived of human social connections (Cacioppo & Patrick, 2008). People find it very stressful to be entirely alone for a long period of time (Schachter, 1959). In fact, people claim to feel more fulfilled in an unhappy relationship than they do when in no relationship at all (Kamp Dush & Amato, 2005). Loneliness is such a miserable state that people often try to numb their pain by turning to alcohol or drugs (Rook, 1984). Over time, loneliness contributes to a range of mental health complications, including depression, eating disorders, and schizophrenia (Cacioppo et al., 2006; Segrin, 1998).

Loneliness also can take a toll on physical health. During times of loneliness, college students have weaker immune systems, making them more vulnerable to catching a cold or flu (Pressman et al., 2005). Looking across the life span, we see that people who have few friends or lovers are likely to die at a younger age than those who are happily connected to others. In one study, people who lacked close social bonds were two to three times more likely to die over a nine-year span (Berkman & Glass, 2000). In fact, when it comes to predicting people’s physical health, loneliness is as significant a risk factor as smoking and obesity (Hawkley et al., 2009).

Aside from feeling lonely, the experience of being rejected outright or pushed away by close others takes a serious toll on mental and physical health (Cohen, 2004; Ryff & Singer, 2000). When people are rejected or stigmatized, they report feeling very distressed (Leary, 2001; Smart Richman & Leary, 2009; Williams, 2007). They also have a great deal of difficulty concentrating on tasks (Baumeister et al., 2002). The effects of divorce provide another way to look at the consequences of separation and rejection. Compared with people who are happily married, those who just got divorced are much more likely to be admitted to hospitals for psychological problems (Bloom et al., 1979). After a divorce, people’s blood pressure increases, and their immune systems become weaker (Kiecolt-Glaser & Newton, 2001), and they are more likely to die an early death than individuals in long-term unions (Sbarra et al., 2011).

We hope you’re convinced by now that social relationships are essential for a good, long life. But an important question remains unanswered: Where did this need come from? Why do virtually all of us care so much about forming and maintaining relationships? A good answer is provided by considering how our species evolved its social needs.

510

From an evolutionary perspective, early humans who successfully formed close social bonds were more likely to survive and reproduce than were the loners, outcasts, and misanthropes. As a result, more and more people were born with gregari-ousness built into their genes. In this way, over thousands of generations, the need to belong came to be a basic characteristic of our species (Baumeister & Leary, 1995; Buss & Schmitt, 1993; Simpson & Kenrick, 1997).

What made it advantageous for our ancestors to form and maintain social relationships? To answer this question, try to envision yourself in the environments of our hominid ancestors—environments very different from the ones we live in today. You are in a desert or forested area, and every day you’re scrambling to find food (no pizza delivery), looking out for dangerous predators, and protecting yourself from illness and harsh climates.

In those environments, being embedded in a network of social relationships helped people survive and have children who would grow to maturity and also reproduce. Most obviously, heterosexual relationship bonds provide the opportunity to have sex, which obviously increases chances of reproduction. Also, hominid infants were especially vulnerable and dependent for many years after birth. Thus, infants with a tendency to form close attachments to their parents would have been more likely than aloof offspring to receive the care and protection they needed to survive until they could function on their own (Bowlby, 1969, 1973, 1980; Buss, 1994). Also, friendships were a means for non-kin to cooperate in finding food, build shelters, and explore the environment. They also helped people avoid the costs of competition and aggression (Fehr, 1996; Trivers, 1971). Such friendships might also have contributed to survival by improving individuals’ ability to defend against predators’ attacks.

In short, those early ancestors disposed to join in, lend a hand, listen to others, care, and be interdependent were more likely to enjoy all of the benefits of stable, affectionate connections to others. As a result, they were more likely to have offspring and to raise those offspring to maturity so that they could reproduce as well.

Although this evolutionary explanation for a need to belong makes sense, it relies on speculative assumptions about the primeval social environment in which our ancestors lived. Therefore, it is important to consider the evidence that the need to establish and maintain intimate bonds with others has an evolutionary basis. Here are four pieces of evidence:

The motive to belong is universal. In every culture that has been examined, people care deeply about forming and maintaining romantic bonds, parent-offspring attachments, and close relations with siblings, friends, and group members (e.g., Eibl-Eibesfeldt, 1989).

Innate affiliation behaviors. Soon after human infants exit the womb, they instinctively engage with other people (Murray & Trevarthen, 1986). They pay special attention to other people’s faces, and they delight in mimicking others’ facial expressions (Meltzoff & Moore, 1977). They also pay particular attention to human voices, especially when others use baby talk (Cooper & Aslin, 1990). These tendencies are seen in children born all over the world, and they are not seen in other species.

Rejection hurts—literally. Earlier we noted that the experience of social rejection causes a great deal of subjective distress. Here we add that the human nervous system responds to rejection with a stress response similar to our response to physical pain. Even minor forms of rejection—such as hearing someone spread unkind gossip about oneself—increases stress-related cardiovascular arousal and a flood of the stress hormone cortisol. Similarly, as we noted in chapter 6, when people experience rejection (for example, when they are playing an interactive computer game with others and they are ignored), they show increased activation of the anterior cingulate cortex, a region of the brain that processes physically painful stimuli (Eisenberger et al., 2003).

According to MacDonald and Leary (2005), the similarity of the stress responses to physical pain and social rejection makes perfect sense if we think about the need to belong as an evolved tendency. Those individuals who felt horrible pain when they were rejected were presumably more motivated to alleviate that pain by repairing their relationships, thereby increasing their chances of producing offspring who would survive and thrive. Those who were less rattled by social rejection simply may have gone off on their own, but such people would be less likely to survive and continue to contribute to the human gene pool. However, people who are too afraid of rejection—that is, high in rejection sensitivity—may avoid seeking social relationships so much that they become dysfunctional. Indeed, people especially high in sensitivity to rejection do not function well socially (Downey & Feldman, 1996).

511

Reproductive success. Adults who form stable close relationships are more likely to reproduce than those who fail to form them. Long-term relationships tend to increase the chances that the offspring will survive and reach maturity (Buss & Schmitt, 1993).