The World Health Organization identifies three pillars of health: physical, mental, and social. On all three fronts, the warning signs are impossible to ignore.
Physically, hypertension, diabetes, and cancer continue to climb. Inflammatory bowel disease is surging. On the mental health front, depression and bipolar disorder have become almost routine diagnoses, while schizophrenia, anxiety disorders, sleep disorders, and obsessive-compulsive disorder are all rising at alarming rates. And socially, the picture may be most concerning of all. The growth of single-person households, declining marriage and birth rates, and a rapidly aging population have created an epidemic of isolation. Elderly people living alone, dying alone, their passing unnoticed for days or weeks. For more than a decade running, South Korea has held the grim distinction of the highest suicide rate among OECD nations. Television is filled with programs about marital conflict and generational friction. Tensions between neighbors, between regions, between genders — and now, piled on top of everything, the social distancing mandated by COVID-19. The health of our nation is under threat from every direction.
Are we really happy right now?
Let me share something that happened a long time ago. One day I scolded the senior student representative in my research lab. What I was hoping was that this student would rally the team: Let's get ourselves together and do the work properly. What actually happened was that the student I had reprimanded turned around and snapped at the other students, blaming them and venting frustration. The lab atmosphere, predictably, went downhill fast. I told myself I had been calm and rational in delivering my criticism. The truth was simpler and uglier: I was overwhelmed with my own workload and had vented my irritation. This student just happened to be in the line of fire. It became one of the worst memories of my career as an advisor — my pointless outburst rippling outward. Those graduate students probably went home that evening and took their anger out on parents, siblings, or partners, straining even more relationships.
This is how life works. We do not exist in isolation. We live woven into relationships with other people, and our emotions are remarkably contagious. Spend time with someone who is happy, and happiness rubs off on you. Spend time with someone who is down, and you start to feel heavy too. Be around someone whose oxytocin is high, and your own levels rise. Live alongside someone whose cortisol is chronically elevated, and your cortisol starts spiking in sympathy.
Now imagine the reverse. A person with naturally high oxytocin joins your team at work. This person listens attentively to their boss, trusts their colleagues, and is consistently kind. They share food, maintain warm eye contact during conversations, and think of others first. When someone like this joins a department, the oxytocin levels of everyone around them would climb significantly. Even when tough situations arise or unexpected problems hit, the work would feel lighter and more manageable. And the effect would not stop at the department's walls — it would spread to other teams, to those employees' families, to partner organizations, outward and outward.
This is not wishful thinking. Nicholas Christakis and James Fowler, authors of Connected, tracked more than 12,067 individuals across over 50,000 social connections for years. They showed that obesity does not just spread to your friends — it spreads to your friends' friends, and even to your friends' friends' friends. If every reader of this book practiced the oxytocin lifestyle at home, the positive effects would reach not only spouses, parents, friends, and colleagues, not only the stranger you happen to meet today, but outward through the groups and communities you belong to, and eventually into the fabric of society itself. This is not arithmetic growth. It is exponential.
Recently I sat down with Professor Seo Eun-guk, author of The Origin of Happiness, and we spent a long evening discussing the relationship between extraversion and happiness, with oxytocin woven into the conversation throughout. He admitted, with a shrug and a smile, that he had not been aware of all the connections between oxytocin and social relationships, physical health, and mental well-being explored in this book. But, he added, he was not the slightest bit surprised that oxytocin was involved in all of them. Oxytocin is the hormone of cheug-eun-ji-sim (compassion for the suffering of others), yeok-ji-sa-ji (the ability to put yourself in someone else's shoes), and i-sim-jeon-sim (heart-to-heart understanding without words) — three principles that have guided Korean life for centuries.
Whether you explain this through the lens of social evolution — kind people survived because their kindness earned them help when they needed it most — or through a religious lens — we were created to love and care for one another, and that is why we feel truly happy only when we do — the core truth remains the same. Oxytocin is at the center of it all. Which of these two worldviews is correct is a question beyond the scope of this book. But imagine a country where more and more people have high oxytocin, and more and more of them share its benefits with those around them. How much more beautiful and happy would that country be?
Carrying this vision, I — as a researcher devoted to health — began thinking years ago about how lifestyle changes could improve both individual well-being and the health of communities. That search led me to oxytocin. There was a kind of serendipity to it: my doctoral research in Canada had focused on the endocrine system, and my postdoctoral work at Harvard centered on the feeding center, the hypothalamus, and the pituitary gland — all of which gave me a strong foundation for understanding this remarkable hormone. And as I read paper after paper on oxytocin, I found it impossible not to be drawn in. What first surprised me was the discovery that oxytocin is fundamentally a hormone of sociality and connection. What surprised me a second time was its deep links to the diseases of modern life.
"Let Us Meet, Share, and Love — Earnestly."
Oxytocin is produced when we meet people, look into each other's eyes, talk, touch, and love. When it runs low, we do not just become unhappy — we get sick. The painful reality is that people in this country are gradually losing the ability to meet, talk, and love. Chronic disease and mental illness are climbing steeply. The COVID-19 pandemic turned isolation into official policy, and as rapid aging and automation advance together, ordering a bowl of soup at a restaurant now means tapping a kiosk screen, and getting noodles delivered to your door is entirely contactless. It is genuinely sad. The massive popularity of the Korean variety show I Live Alone tells us how many people see themselves in a solitary existence. The emergence of the word untact — contactless — signals that we are standing at the tail end of a dystopian inheritance in which meeting another person face to face has become the thing that feels strange.
And yet: all life and all happiness begin with human touch. No matter how far society pushes into social networks, the metaverse, and the latest advances in artificial intelligence, one truth remains fixed. Every meeting and relationship grounded in our physical bodies is what built the enormous structure we call civilization. In the film Ready Player One, the dying Dr. Halliday delivers his final message to the protagonist lost in a virtual world: "Go back to reality. That's the only place where you can get a decent meal." In an age that has moved beyond the nuclear family into the era of the "nuclear individual," we need to rewrite the narrative of connection — the oxytocin story — if we want to build healthier people and happier communities.
Put this book down. Right now. Call up a friend you have not seen in far too long and drag them out for a drink. Take a plate of pajeon — Korean scallion pancakes — to a neighbor you have grown awkwardly distant from. Go on a proper downtown date with your spouse, the kind you have not had since the two of you drifted into sleeping in separate rooms. I would love to see that.
Over the six months I spent writing this book, my own oxytocin was almost certainly higher than it has ever been. I noticed it only afterward: I had been listening more attentively to my elders, looking more carefully into the eyes of the people I talked with, treating my family with more tenderness, holding them more often, and showing more patience and care to colleagues and students. They say that knowledge is power, and that you see as much as you know. As I finish this manuscript, my deepest hope is that this book broadens your perspective — even a little — and helps make this wonderful country of ours a happier place to live.
And I pray that this book — even if it amounts to no more than a speck of dust, even if it is as small as a single mustard seed — plants something that grows toward a healthier, more loving nation.
Thank you.