Photograph by Peter Marlow / Magnum

When Nicolae Ceaușescu came to power, in the mid-nineteen-sixties, Romania saw the proliferation of leagăne—literally, “cradles,” otherwise known as institutional homes for the very young. Ceaușescu wanted to increase Romania’s industrial output, and he thought that that required a larger population. In 1966, he enacted Decree 770, which restricted contraceptives, banned almost all abortions for women who hadn’t had at least four children, and instituted a thirty-per-cent income tax on childless men and women who were over the age of twenty-five. In the span of a single year, the birth rate rose by thirteen per cent and the infant population nearly doubled. But even that wasn’t enough: in 1985, the dictator raised the minimum number of children to five and the age of the women covered by the decree from forty to forty-five. The result was one of the saddest natural experiments in modern psychology. Thousands of children, from birth to the age of three, grew up neglected in understaffed institutions, often experiencing severe sensory deprivation in their formative months.

Few people outside Romania initially knew about the leagăne. But when Ceaușescu was deposed, in 1989, images of the children reached television screens around the world. In 1994, Mary Carlson and her husband, Felton Earls, travelled to Romania to learn more about the effects of maternal deprivation on these children.* Carlson is a neurobiologist at Harvard Medical School, and Earls is a Harvard psychiatrist. A former student of Harry Harlow, the psychologist who is best known for his studies of socially deprived monkeys, Carlson, as she and Earls later wrote, found familiar “the muteness, blank facial expressions, social withdrawal, and bizarre stereotypic movements of these infants.” These behaviors “bore a strong resemblance” to the types of reactions that Carlson had seen in socially deprived monkeys and chimpanzees. She was also aware of studies of rats that showed how tactile stimulation could affect levels of the stress hormone cortisol during early development.

At a leagăne in the Romanian city of Iași, a child-development specialist named Joseph Sparling had organized a yearlong early-enrichment program for a group of infants, sparing them from the severe neglect and sensory deprivation typical of care in these institutions. The child-to-caregiver ratio for the children in the program was four to one, compared with the institutional standard of twenty to one. Carlson and Earls measured the cortisol levels of the enriched children, as well as of children in a control group. They took saliva samples multiple times a day, tracking how cortisol levels fluctuated over time and in response to stressful events. The levels of the children in the control group, they found, were off kilter, while the levels of the enriched children were more like those of Romanian children who had been home-reared. Cortisol in children who are home-reared tends to peak just before they wake up and then taper off; in the leagăne infants of the control group, cortisol peaked in the afternoon and remained elevated. That pattern, in turn, correlated with lower performance on numerous cognitive and physical assessments. By contrast, the children in Sparling’s enrichment program, who were receiving higher-quality care and more attention, performed better both physically and behaviorally.

In 1997, Carlson and Earls published their results. “The implications for the cognitive and social development of future generations of adults in this society are potentially serious when one considers that most Romanian children spend significant amounts of time in some form of institutional setting,” they wrote. In a subsequent interview, Carlson said of the study, “When the enriched kids returned to the typical conditions that involved little touching, the physical and behavioral advantage they had obtained faded. Although the enriched group showed a better response to stress as long as eighteen months later, they still were socially withdrawn and failed to respond normally to other children and adults.”

Touch is the first of the senses to develop in the human infant, and it remains perhaps the most emotionally central throughout our lives. While many researchers have appreciated its power, others have been more circumspect. Writing in 1928, John B. Watson, one of the originators of the behaviorist school of psychology, urged parents to maintain a physical boundary between themselves and their children: “Never hug and kiss them, never let them sit on your lap. If you must, kiss them once on the forehead when they say goodnight. Shake hands with them in the morning. Give them a pat on the head if they have made an extraordinarily good job on a difficult task.” Watson acknowledged that children must be bathed, clothed, and cared for, but he believed that excessive touching—that is, caressing—would create “mawkish” adults. An untouched child, he argued, “enters manhood so bulwarked with stable work and emotional habits that no adversity can quite overwhelm him.” Now we know that, to attain that result, he should have suggested the opposite: touch, as frequent and as caring as possible.

Like our other senses, touch comes in gradations. It is governed by an exquisite array of receptors that can distinguish minute variations in the external environment. Fast, slow, or in between? Hard, soft, or something else? Hot, cold, warm? Some receptors react only to caresses. Some send pain signals. Some tell us that we have an itch. Each type activates a different part of the brain, making us feel soothed or hurt, comfortable or distressed, angry or calm. In his recent book “Touch: The Science of Hand, Heart, and Mind,” the Johns Hopkins University neuroscientist David Linden cites “the electric touch of romantic love, the unsettling feeling of being watched, the relief of pain from mindful practice, or the essential touch that newborns need to thrive.” All of these diverse sensations, he writes, “flow from the evolved nature of our skin, nerves, and brain.”

The evolutionary psychologist Robin Dunbar has found that, among other primates, the frequency of grooming is a consistent proxy for group size and coherence. Similarly, among humans, touch might seem to serve as little more than a proxy for social bonds: if we often experience friendly or loving caresses, it’s safe to assume that we have a strong social network, which is itself one of the best predictors of happiness, health, and longevity. It’s easy to see how an elderly person who is regularly visited by a massage therapist might be happier and healthier than one who isn’t—even if the massage, as such, does nothing. In the case of the Romanian infants, it’s easy to imagine that a child who has a steady caretaker will be emotionally stronger than a child who languishes, abandoned, for long stretches of time—whether or not that caretaker takes particular pains to cuddle. It could be, in short, that the benefits of touch are really social benefits.

In fact, though, researchers have discovered that touch need not be social to be effective. In her more than thirty years of research on touch, Tiffany Field, the head of the Touch Research Institute at the University of Miami’s Miller School of Medicine, has sought repeatedly to disentangle the two. In one series of studies, one group of elderly participants received regular, conversation-filled social visits while another received social visits that also included massage; the second group saw emotional and cognitive benefits over and above those of the first. Field has found similar gains in both premature and full-term infants, pregnant women, children and adults with chronic pain conditions or emotional problems, and healthy adults. Even short bursts of touch—as little as fifteen minutes in the evening, in one of her studies—not only enhance growth and weight gain in children but also lead to emotional, physical, and cognitive improvements in adults. Touch itself appears to stimulate our bodies to react in very specific ways. The right kind can lower blood pressure, heart rate, and cortisol levels, stimulate the hippocampus (an area of the brain that is central to memory), and drive the release of a host of hormones and neuropeptides that have been linked to positive and uplifting emotions. The physical effects of touch are far-reaching.