What Harvard’s Longest Study on Happiness Reveals About Jesus’ Command to Love

Nearly two thousand years ago, Jesus told us to love one another. Today, the Harvard happiness study is catching up, showing just how central relationships are to human happiness, health, and flourishing.

“Love one another. As I have loved you...” — John 13:34

We hear the word love so often that it is easy to reduce Jesus’ words to religious sentiment: be nice, care about people, try to get along. But modern psychology is discovering something much more interesting.

One of the longest-running studies of adult life has spent more than eight decades following people across their lives, examining their health, relationships, work, emotional well-being, and aging. The Harvard Study of Adult Development began in 1938 and eventually expanded beyond its original participants to include spouses and descendants. Its most enduring conclusion is remarkably straightforward:

The quality of our relationships matters enormously to the quality of our lives.

People who remain meaningfully connected to others tend to be happier and healthier, and strong relationships appear to help protect us as we age. Science did not prove the Gospel of John. But science may be discovering something about the kind of creature the Gospel has always understood us to be.

“The surprising finding is that our relationships and how happy we are in our relationships has a powerful influence on our health,” said Robert Waldinger, director of the study, a psychiatrist at Massachusetts General Hospital, and a professor of psychiatry at Harvard Medical School. “Taking care of your body is important, but tending to your relationships is a form of self-care too. That, I think, is the revelation.”

We Were Not Made to Live Alone

Modern culture places enormous emphasis on individual achievement. We pursue careers, money, education, status, recognition, possessions, and independence. None of those things is necessarily bad, and some are necessary parts of a responsible life. The problem begins when we expect them to provide something they cannot.

Robert Waldinger, who has directed the Harvard Study of Adult Development for more than two decades, has repeatedly emphasized the importance of relationships to health and happiness. The significant issue is not simply how many people we know, but whether we have relationships that provide connection, support, and a sense that we matter to someone. Harvard researchers are now also studying the biological mechanisms through which relationships may help protect us from the effects of stress.

Christianity should not find this especially surprising. The biblical account of the human person is relational from its opening chapters. Human beings are created for relationship with God and with one another. The Christian ideal is not the radically independent individual who needs nobody else. We are members of families, communities, friendships, marriages, parishes, and ultimately what St. Paul describes as one body.

Perhaps one of the mistakes of modern life is that we have confused independence with maturity. There is certainly a healthy independence that allows a person to take responsibility for his own life. But that is very different from isolation. Mature people do not need nobody; they learn how to need others without making others responsible for everything they feel.

 

"A new command I give you: Love one another. As I have loved you, so you must love one another. By this everyone will know that you are my disciples if you love one another.” — John 13:34-35

What Science Can Tell Us—and What It Cannot

The Harvard research is fascinating partly because it allows us to measure some of the consequences of human connection. Scientists can examine health outcomes, loneliness, stress, emotional well-being, aging, and other measurable variables. Increasingly, researchers are studying how relationships may influence the physiological systems involved in stress and resilience.

But there is an important boundary here.

Science can tell us a great deal about what tends to happen when people have strong relationships. It cannot, by itself, tell us why we ought to love another person. It cannot put human dignity under a microscope or determine whether sacrificing for another person is morally good. It can describe consequences and correlations, but the question of meaning belongs to a larger discussion about what a human being is and what a human life is for.

That distinction is central to my forthcoming book, The Science of the Cross: Stress, Suffering, and the Psychology of Transformation. The book examines places where psychology, neuroscience, philosophy, and Christian thought illuminate different dimensions of the same human experience. Psychology can tell us extraordinary things about how we function, but human beings cannot be fully explained by brain chemistry, behavior, or measurable outcomes alone.

The Science of the Cross

What Did Jesus Mean by Love?

One difficulty is that the English word love is asked to describe very different experiences. We love our spouse, our children, our closest friend, our country, our dog, and sometimes even our favorite restaurant. Obviously, we do not mean precisely the same thing in each case.

The classical Christian tradition inherited distinctions that help make sense of this. Eros refers broadly to romantic or desirous love, storge to familial affection, and philia to friendship. Christian thought has placed particular emphasis on agape, the self-giving love that seeks the good of another.

That last distinction matters because Christian love cannot be reduced to emotion. Feelings are real and important, but they change. A husband can love his wife while also being angry with her. A mother can love her child while feeling exhausted, frustrated, or disappointed. A person can choose to behave lovingly at the very moment when warm feelings are conspicuously absent.

Love therefore involves more than what happens to us emotionally. It also involves what we choose to do.

That is why relationships require work. Listening when we would rather defend ourselves, forgiving when resentment feels justified, remaining present when another person is suffering, apologizing when our pride wants to explain why we were technically right, and sacrificing our convenience for someone else's good are not merely feelings. They are actions.

Jesus Goes Further Than the Harvard Study

This is where the Gospel becomes more demanding than a study of happiness.

The Harvard findings can reasonably encourage us to invest in healthy relationships because relationships are associated with greater health and well-being. Jesus does something more. He does not simply say, “Build a supportive social network.” He says, “Love one another as I have loved you.”

Those words are spoken in the shadow of the Cross.

The Christian model of love is therefore not merely companionship, emotional support, or surrounding ourselves with people who make life more pleasant. Those things have real value, but the love Christ describes is self-giving. It is a love willing to bear a cost for the good of another person.

Anyone who has truly loved already understands something about this. Marriage brings companionship, but it also brings sacrifice. Raising children can produce extraordinary joy, but it also brings worry, exhaustion, responsibility, and sometimes heartbreak. Caring for an elderly parent may deepen a relationship while simultaneously making life considerably more difficult.

We often talk about love as though its purpose were to make us feel good. Christianity gives us a far more complicated picture. Love can enrich our lives while also making us vulnerable to suffering.

The people capable of giving us our greatest joy are often the same people whose suffering, rejection, illness, or death can cause us our greatest pain. Eliminating that vulnerability would require eliminating deep love itself.

The Christian Symbol of Love Is the Cross

This brings us to a paradox that interests me both psychologically and theologically. If good relationships contribute to human flourishing, why does Christianity so often associate love with sacrifice?

Because meaningful relationships inevitably ask something of us.

The Cross does not teach that pain is good for its own sake, nor does Christianity require us to romanticize abusive or destructive relationships. But the Cross does challenge the modern assumption that the good life is primarily a life from which discomfort has been removed.

Sometimes the most meaningful things we do are difficult precisely because something important is at stake.

A parent gets out of bed repeatedly for a sick child not because sleep deprivation is good, but because the child is worth the sacrifice. A spouse remains present during a frightening illness not because suffering is desirable, but because love gives the suffering a context and a meaning. A person forgives not because betrayal suddenly becomes acceptable, but because refusing to be permanently governed by resentment may be part of becoming free.

This is one of the themes I explore in The Science of the Cross. Human beings do not experience difficulty merely according to its intensity. Meaning, responsibility, interpretation, hope, and relationship all influence how burdens are carried. The question is not whether suffering is good. Much suffering is terrible and should be prevented where possible. The more interesting question is why some difficult experiences can become part of growth rather than merely sources of damage.

Relationships Can Change the Experience of Stress

The continuing Harvard research makes this connection particularly interesting. Waldinger and others are now examining the mechanisms through which supportive relationships may help regulate stress. The external difficulty does not necessarily disappear simply because someone is standing beside us, but our experience of that difficulty can change.

Most of us know this intuitively.

Facing a frightening medical diagnosis alone is different from facing it with a spouse who takes your hand and says, “Whatever happens, we will deal with it together.” Financial difficulty is still financial difficulty, but isolation can make the same problem feel more threatening. Grief remains painful even when surrounded by people who love us, yet grief carried within a community is different from grief carried entirely alone.

Psychology helps explain why this matters. Human beings do not respond only to events themselves. We also respond to what we believe those events mean, whether we think we possess the resources necessary to cope with them, and whether we expect to face them alone.

Christianity has always had a communal dimension for precisely this reason. The Church was never intended to be a collection of isolated individuals who happened to occupy the same building once a week. St. Paul calls Christians a body. The language implies dependence, responsibility, and connection.

Love Is Something We Practice

Relationships do not remain healthy simply because they once mattered to us. They require attention.

This may be another area where psychology and the traditional Christian understanding of virtue unexpectedly meet. We tend to become better at what we repeatedly practice. Patience develops through opportunities to be patient. Courage grows when we repeatedly confront things that frighten us rather than always avoiding them. Forgiveness becomes more possible when we learn how to move through anger without allowing it to dictate every decision.

Love develops in a similar way.

We do not need to wait until we feel perfectly loving before behaving lovingly. Sometimes the behavior precedes the feeling. We make the phone call. We listen. We show up. We apologize. We put down the phone and pay attention. We keep a promise that has become inconvenient.

Over time, repeated actions help shape the kind of person we become.

Christianity traditionally calls this the formation of virtue. Psychology may use different language, but both recognize that character is not produced by good intentions alone.

Perhaps Jesus Was Telling Us Something About Ourselves

The Harvard Study of Adult Development does not prove Christianity, and Christianity does not need a longitudinal research study to validate the words of Christ.

The overlap is nevertheless worth considering.

Religious commandments are sometimes treated as arbitrary restrictions imposed upon human beings by an external authority. Christianity makes a different claim. Its moral vision is grounded in an understanding of what a human being is and what ultimately allows human beings to flourish.

Seen from that perspective, Christ's command to love one another may be more than an obligation added to an already crowded list of religious duties. It may also be a revelation about ourselves.

We are relational creatures. We need others, and others need us. Healthy relationships appear to influence not only our happiness but also our physical well-being and our ability to cope with stress. Science is becoming increasingly sophisticated in explaining how some of this happens.

Christianity asks the question that remains after the measurements are complete: What kind of person must I become in order to truly love another person?

That question reaches beyond happiness. It reaches into sacrifice, responsibility, forgiveness, virtue, suffering, and ultimately the Cross. And perhaps that is why Jesus did not merely tell his disciples to love, he told them how:

“As I have loved you.”

The Science of the Cross

Stress, Suffering, and the Psychology of Transformation

My forthcoming book explores this same intersection between psychology and Christian thought: what science can tell us about stress, resilience, meaning, relationships, suffering, and change—and the questions about the human person that science alone cannot answer.

Learn more about The Science of the Cross