When I tell people that, as a psychologist, one of my main areas of interest is interpersonal attraction, I’m sometimes met with a certain condescension that still surprises me. Should psychologists really be wasting their time studying something as trivial and frivolous as attraction? Aren’t there more important things for social psychologists to be concerned about, like aggression or conformity? I usually have a number of stock answers to these questions, one of which is that the things that most people take for granted about attraction turn out to not actually be true. As we’ll see over the coming months, for example, opposites very rarely attract, but the only reason why we know that is because someone somewhere took the time to test the idea.

Another of my favorite responses is that the study of interpersonal attraction isn’t as trivial as most people think. Underpinning the way in which we form interpersonal relationships is what social psychologists call our “need to belong.” Although there are times when we want nothing more than to be on our own, most people have a pervasive need to form and maintain enduring, close relationships with others.

We are, according to Aristotle, “social animals.” And there is a good reason for this: People who have more reliable networks of social ties have higher self-esteem than those who live more isolated lives. They also tend to be happier and more satisfied with life, physically healthier, and less likely to die a premature death. Studying attraction just became a little more important.

Perhaps the best way of testing whether we really are “social animals” is to examine what happens when we’re isolated from others. Harry Harlow’s famous (or, depending on your point of view, infamous) experiments on newborn rhesus monkeys provide a useful starting point. In one of Harlow’s experiments, baby monkeys were separated from their mothers at birth and raised in isolation for up to 12 months. Some monkeys were provided with artificial mothers that consisted of no more than a wire frame, or a wire frame covered with towelling cloth and with a primitive face. Harlow found that baby monkeys spent considerably more time with the cloth mothers than the wire mothers, which he took as evidence of the importance of contact comfort in the formation of mother-child bonds.

More controversially, perhaps, Harlow’s research was extended to baby monkeys that were totally isolated from contact with any living thing for up to 12 months. He found that these monkeys were emotionally damaged. Most began biting themselves, rocked back and forth repetitively, refused to play with other monkeys and failed to defend themselves from physical attacks.

As adults, the monkeys isolated at birth were sexually incompetent and, as parents (achieved through artificial insemination), they exhibited poor parenting behaviour (one monkey bit her baby to death). In short, rhesus monkeys isolated at birth failed to make a satisfactory adjustment to social life as adults.

Human infants show similar social and mental deficits if they experience prolonged social deprivation following birth. The Hungarian psychoanalyst René Spitz coined the term “hospitalism” to describe the psychological condition of babies who had been left in an overcrowded institution, where they were fed but were rarely handled and where they spent most of their time in their cots. Not only were these babies found to be mentally and socially less advanced than institutionalized children who had been given adequate care, they were also more likely to suffer premature deaths. In more extreme cases, children who have been totally deprived of human contact for a period of several years sometimes behave as if they have been reared in the wild, which is why they are referred to as “feral children.”

Of course, these are extreme examples, but the work of child psychiatrist John Bowlby supports the idea that we have a need to be with others. His ground-breaking work on the attachment behavior showed that infants try and maintain physical proximity with their mothers. If that proximity was disrupted, infants exhibited “signal behaviors” such as crying, clinging or following, which Bowlby attributed to an innate affiliative drive. In other words, needing to affiliate with others appears to be an important and basic human motive.

Among adults, too, social deprivation can have adverse consequences. The case of Rear Admiral Richard Byrd provides a useful example from the field: Byrd volunteered to spend several months alone at an Antarctic weather station in 1934. After only about a month, Byrd wrote that he began to feel extremely lonely and bewildered, and that he passed the time by imagining he was among familiar people. After two months, he dwelt on “the meaning of life” and returned to the idea that he was not alone, writing, “Though I am cut off from human beings, I am not alone.” After three months, he was severely depressed and apathetic, experienced hallucinations, and was in poor physical health (the state his rescuers found him in).

As the example of Byrd suggests, loneliness and social deprivation can have adverse effects on our wellbeing. Interestingly, loneliness is most likely to occur during periods of transition—moving away to college, after breaking up with a romantic partner or when a close companion moves away.

The end of a relationship appears to be particularly important when it comes to loneliness. People who are recently widowed, divorced or separated appear to experience greater loneliness than those who have never been married. And interestingly, the loneliest groups in American society appear to be young adults, particularly those between the ages of 18 to 30—a phenomenon that Harvard professor of public policy Robert Putnam laments in his book, “Bowling Alone.”

Of course, individuals will differ in their need for affiliation or their desire to establish contact with others. In general, however, most people are motivated to establish and maintain a level of contact that is optimum for themselves. Human beings, like laboratory rats, are more likely to approach others after a period of isolation or social deprivation and are less likely to approach others after prolonged contact. Some researchers have suggested that rats, and possibly also humans, have built-in “sociostats” or “social thermostats” that regulate our need for affiliation. In general, we are fairly successful at managing our personal needs when it comes to social contact.

So, here’s the bottom line: Studying and understanding our affiliative needs isn’t as trivial as it would seem. Being denied opportunities to engage in social interaction can have detrimental effects on our wellbeing. Similarly, we get incredibly distressed when we are neglected by others, ostracised, excluded or rejected. In other words, when we experience “social death.” Conversely, forming and maintaining social relationships fills us with joy and can provide some of the best experiences in our lives. It really should come as no surprise to learn that social relationships, along with employment status and physical and mental health, is one of the most important predictors of an individual’s level of happiness.

Understanding affiliation and our need to belong is a necessary first step in the study of interpersonal attraction. Next month, we’ll begin the more difficult task of understanding why we are drawn to some people more than others.