I first met my wife when I went to Canada for a language program. At church, we were simply oppa and dongsaeng — the older-brother, younger-sister dynamic that Koreans fall into so naturally — and nothing more. It was only when I returned to the University of Alberta as an exchange student that we started dating. I had decided to extend my stay by one extra semester, and that single decision changed my life in ways I never could have predicted. My relationship with my wife set off an enormous butterfly effect. From October 1994, we dated with marriage in mind, getting to know each other deeply, spending nearly every waking moment together until the following March, when I had to fly back to Korea for my senior year.
And then came the agony of distance. Every morning, I wrote her a letter. Every night, I ended my day listening to her voice over an outrageously expensive international phone call. To cover those bills, I worked three separate part-time jobs.
I missed her so badly I thought it might actually kill me. Looking back now, I realize the separation anxiety and emptiness were making me physically and emotionally sick — body and mind, all at once. The one consolation was that this painful stretch lasted only three months, cut short by my sudden decision to pursue graduate school abroad. In April of that year, I decided to go. By May, I had my admissions letter in hand and, in a whirlwind, both families' blessings for our marriage. It all happened so fast it felt like bungaetbul-e kong guweo meongneunda — roasting beans over a bolt of lightning, as the Korean expression goes. In June, my wife flew to Korea for the wedding. We married in July and by August were heading back to Canada together. I had entered the country alone; I left it as half of a family. That September, I began my master's program, launching what would become eight years of student life in Canada.
This longing to be near the person you love, this calm that washes over you the moment you are together again — it is not just a romantic feeling or a psychological notion. It is a biologically proven phenomenon. Scientists call it attachment theory. Attachment takes many forms: between parent and child, between siblings, between friends, and between lovers. These bonds exert a lasting influence on personality and temperament, and they reach deep enough to shape both psychological and physical health.
The Importance of Attachment
John Bowlby, the British psychiatrist who founded attachment theory, built his framework on two foundations: the wounds of his own childhood and the clinical experience he gained from treating adolescents with personality disorders. When Bowlby was born, the British upper classes believed that physical affection and emotional warmth would spoil a child. In most well-to-do homes, it was the nanny — not the parent — who raised the children. Bowlby's own parents lived apart; his mother left her children behind to spend half of each year with her husband.
That absence carved a deep wound in the boy's heart. Until the age of four, young Bowlby was cared for by a kind-hearted nanny — but when she left, a much colder, sterner replacement took over. Bowlby later wrote that losing this nanny felt as devastating as losing his own mother. Then, when he was just five, shattering news arrived: his father — a man he had rarely seen — had been killed in the Second Boer War. Through the shock of these losses, Bowlby came to understand, from the inside out, just how vital attachment is for a child.
As an adult, Bowlby opened a psychiatric practice in London, where he encountered a generation of children who had been evacuated from their families during World War II to escape German bombing raids — and who later developed personality disorders. From these observations, he published Forty-Four Juvenile Thieves, classifying the children into six types: normal, depressive, circular, hypomanic, affectionless, and schizoid. Among the forty-four subjects, seventeen had been separated from their parents for more than six months before the age of five. Of the fourteen classified as "affectionless," a striking twelve had endured such early separation. These findings proved instrumental in establishing attachment theory's central claim: that early caregiving, environment, and the process of forming bonds with parents profoundly shape a child's character.
Bowlby's work had a deep influence on the American psychologist Harry Harlow. Though Harlow is now synonymous with primate research, he did not originally set out to study monkeys. When he was hired as an assistant professor at the University of Wisconsin, the animal laboratory had been dismantled, leaving him with nowhere to work. He began by observing monkeys at a nearby zoo, and eventually launched a primate research program of his own. When the zoo monkeys kept dying from infectious disease, Harlow had no choice but to separate infant monkeys from their mothers immediately after birth and raise them in isolation.
What he noticed next changed the field. These motherless baby monkeys not only showed stunted social skills but also developed an intense attachment to the cloth diapers lining their cages. This observation sparked what became his famous wire-and-cloth surrogate mother experiment. The question was deceptively simple: does an infant love its mother because she provides food, or for some other reason entirely? To find out, Harlow placed baby monkeys in cages with two surrogate mothers — one made of bare wire, the other covered in soft cloth. The wire mother held a bottle of milk, so the infant had to go to her to feed. The cloth mother offered nothing to eat — only the warmth and softness of something that felt like an embrace. Then Harlow watched to see which mother the babies chose.
The results were unambiguous. The baby monkeys spent overwhelmingly more time clinging to the cloth mother, visiting the wire one only when hunger forced them. The cloth surrogate won in a landslide. But Harlow was not finished. He pushed the experiment further, introducing a frightening robot monkey into the cage. Would the terrified infants run to the wire mother who fed them, or the cloth mother who only held them? Once again, the cloth mother won decisively. The babies scrambled into her soft arms and held on with everything they had. (Or more accurately, held her with everything they had.) And then something happened that even Harlow had not predicted. Safely pressed against the cloth mother, the baby monkey turned around to face the robot and started screaming at it — as if, with a powerful ally at its back, it had found the courage to stand up to anything. It was exactly the way a child who has always been intimidated by a bigger kid will suddenly talk back the moment his mother takes his hand. Bowlby and Harlow not only cited each other's work to complete their respective theories but also met in person in 1958. It goes without saying that both immediately declared themselves steadfast allies.1
Attachment Is Made of Oxytocin
When Bowlby and Harlow published their research on attachment and the importance of physical touch, the only known function of oxytocin was stimulating uterine contractions during labor. No one yet suspected that this same molecule played a direct role in human bonding. In truth, oxytocin is deeply intertwined with attachment. Mice that lack oxytocin receptors ignore their own pups entirely, but inject oxytocin into a virgin female mouse that has never given birth and she will suddenly begin nurturing newborn pups as tenderly as if they were her own. Conversely, give an oxytocin antagonist to a nursing mother who has been devotedly caring for her young, and she will abandon them without a backward glance. These findings make one thing clear: oxytocin plays a central role in forging the bond between mother and child.2
Similar patterns show up in humans. Mothers with higher oxytocin levels form deeper connections with their unborn babies during pregnancy and show their newborns greater warmth and affection after birth. They respond more sensitively to their baby's sounds — even from deep sleep — and are better at the intimate, wordless exchange of eye contact. That physical touch between mother and child is critical for normal brain development has been confirmed by study after study, in both animals and humans. And oxytocin matters just as much for fathers. In an experiment with thirty-three fathers and their infants aged four to eight months, fathers who inhaled oxytocin engaged in significantly more physical touch and social interaction with their children — and their children's oxytocin levels rose in tandem. The babies looked at their fathers more, smiled more, reached out more, and even displayed more adventurous behavior, boldly exploring unfamiliar objects. A boost in the father's oxytocin transformed the entire parent-child relationship into something richer and more meaningful.3
The influence of oxytocin on attachment goes well beyond the parent-child bond. A wealth of research has shown that oxytocin promotes positive emotions, a tendency toward gratitude, and healthier relationships with other people. You do not need to dig through dense academic journals to see this — the popular book Whale Done! makes the case plainly, showing that when you praise animals or people, the relationship reliably improves. It is, in many ways, an intuitively obvious finding.
Now imagine bringing that same spirit of praise and gratitude into your romantic relationship. How much happier and more positive might things become? Research shows that couples with higher oxytocin levels exhibit greater mutual empathy, deeper interest in each other, more positive emotions, and more frequent physical affection. Higher blood oxytocin also correlates strongly with more frequent hugging, and women who hugged more showed more stable blood pressure. Oxytocin does not merely add romance to a relationship — it actively safeguards both partners' health.4