The connection between social pain and physical pain illustrates the links between our emotions and the physiological processes of the body. Social rejection doesn’t just cause emotional pain; it affects our physical being. In fact, social relationships are so important to humans that a lack of social connection constitutes a major risk factor for health, rivaling even the effects of cigarette smoking, high blood pressure, obesity, and lack of physical activity. In one study, researchers surveyed 4,775 adults in Alameda County, near San Francisco.6 The subjects completed a questionnaire asking about social ties such as marriage, contacts with extended family and friends, and group affiliation. Each individual’s answers were translated into a number on a “social network index,” with a high number meaning the person had many regular and close social contacts and a low number representing relative social isolation. The researchers then tracked the health of their subjects over the next nine years. Since the subjects had varying backgrounds, the scientists employed mathematical techniques to isolate the effects of social connectivity from risk factors such as smoking and the others I mentioned above, and also from factors like socioeconomic status and reported levels of life satisfaction. They found a striking result. Over the nine-year period, those who’d placed low on the index were twice as likely to die as individuals who were similar with regard to other factors but had placed high on the social network index. Apparently, hermits are bad bets for life insurance underwriters.
SOME SCIENTISTS BELIEVE that the need for social interaction was the driving force behind the evolution of superior human intelligence.7 After all, it is nice to have the mental capacity to realize that we live in a curved four-dimensional space-time manifold, but unless the lives of early humans depended on having a GPS unit to locate the nearest sushi restaurant, the capability to develop such knowledge was not important to the survival of our species and, hence, did not drive our cerebral evolution. On the other hand, social cooperation and the social intelligence it requires seem to have been crucial to our survival. Other primates also exhibit social intelligence, but not nearly to the extent that we do. They may be stronger and faster, but we have the superior ability to band together and coordinate complex activities. Do you need to be smart to be social? Could the need for innate skill at social interaction have been the reason we developed our “higher” intelligence—and could what we usually think of as the triumphs of our intelligence, such as science and literature, be just a by-product?
Eons ago, having a sushi dinner involved skills a bit more advanced than saying, “Pass the wasabi.” It required catching a fish. Before about fifty thousand years ago, humans did not do that; nor did they eat other animals that were available but difficult to catch. Then, rather abruptly (on the evolutionary scale of time), humans changed their behavior.8 According to evidence uncovered in Europe, within the span of just a few millennia people started fishing, catching birds, and hunting down dangerous but tasty and nutritious large animals. At about the same time, they also started building structures for shelter and creating symbolic art and complex burial sites. Suddenly they had both figured out how to gang up on woolly mammoths and begun to participate in the rituals and ceremonies that are the rudiments of what we now call culture. In a brief period of time, the archaeological record of human activity changed more than it had in the previous million years. The sudden manifestation of the modern capacity for culture, ideological complexity, and cooperative social structure—without any change in human anatomy to explain it—is evidence that an important mutation may have occurred within the human brain, a software upgrade, so to speak, that enabled social behavior and thereby bestowed on our species a survival advantage.
When we think of humans versus dogs and cats, or even monkeys, we usually assume that what distinguishes us is our IQ. But if human intelligence evolved for social purposes, then it is our social IQ that ought to be the principal quality that differentiates us from other animals. In particular, what seems special about humans is our desire and ability to understand what other people think and feel. Called “theory of mind,” or “ToM,” this ability gives humans a remarkable power to make sense of other people’s past behavior and to predict how their behavior will unfold given their present or future circumstances. Though there is a conscious, reasoned component to ToM, much of our “theorizing” about what others think and feel occurs subliminally, accomplished through the quick and automatic processes of our unconscious mind. For example, if you see a woman racing toward a bus that pulls away before she can get on it, you know without giving it any thought that she was frustrated and possibly ticked off about not reaching the bus in time, and when you see a woman moving her fork toward and away from a piece of chocolate cake, you assume she’s concerned about her weight. Our tendency to automatically infer mental states is so powerful that we apply it not only to other people but to animals and even, as the six-month-olds did in the wooden disk study I described above, to inanimate geometrical shapes.9
It is difficult to overestimate the importance to the human species of ToM. We take the operation of our societies for granted, but many of our activities in everyday life are possible only as a result of group efforts, of human cooperation on a large scale. Building a car, for example, requires the participation of thousands of people with diverse skills, in diverse lands, performing diverse tasks. Metals like iron must be extracted from the ground and processed; glass, rubber, and plastics must be created from numerous chemical precursors and molded; batteries, radiators, and countless other parts must be produced; electronic and mechanical systems must be designed; and it all must come together, coordinated from far and wide, in one factory so that the car can be assembled. Today, even the coffee and bagel you might consume while driving to work in the morning is the result of the activities of people all over the world—wheat farmers in one state, bakers most likely in another, dairy farmers yet elsewhere; coffee plantation workers in another country, and roasters hopefully closer to you; truckers and merchant marines to bring it all together; and all the people who make the roasters, tractors, trucks, ships, fertilizer, and whatever other devices and ingredients are involved. It is ToM that enables us to form the large and sophisticated social systems, from farming communities to large corporations, upon which our world is based.
Scientists are still debating whether nonhuman primates use ToM in their social activities, but if they do, it seems to be at only a very basic level.10 Humans are the only animal whose relationships and social organization make high demands on an individual’s ToM. Pure intelligence (and dexterity) aside, that’s why fish can’t build boats and monkeys don’t set up fruit stands. Pulling off such feats makes human beings unique among the animals. In our species, rudimentary ToM develops in the first year. By age four, nearly all human children have gained the ability to assess other people’s mental states.11 When ToM breaks down, as in autism, people can have difficulty functioning in society. In his book An Anthropologist on Mars, the clinical neurologist Oliver Sacks profiled Temple Grandin, a high-functioning autistic woman. She had told him about what it was like to go to the playground when she was a child, observing the other children’s responses to social signals she could not herself perceive. “Something was going on between the other kids,” he described her as thinking, “something swift, subtle, constantly changing—an exchange of meanings, a negotiation, a swiftness of understanding so remarkable that sometimes she wondered if they were all telepathic.”12