The Harvard Study of Adult Development, one of the world’s longest studies of adult life, has produced a wealth of data on physical and mental health of human over time. When scientists began tracking the health of 268 Harvard sophomores in 1938 during the Great Depression, they hoped the longitudinal study would reveal clues to leading healthy and happy lives.

“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.”

Close relationships, more than money or fame, are what keep people happy throughout their lives, the study revealed. Those ties protect people from life’s discontents, help to delay mental and physical decline, and are better predictors of long and happy lives than social class, IQ, or even genes.

“When we gathered together everything we knew about them about at age 50, it wasn’t their middle-age cholesterol levels that predicted how they were going to grow old,” said Waldinger in a popular TED Talk. “It was how satisfied they were in their relationships. The people who were the most satisfied in their relationships at age 50 were the healthiest at age 80.”

“When the study began, nobody cared about empathy or attachment. But the key to healthy aging is relationships, relationships, relationships.” George Vaillant, director of the study from 1972-2004.

(Note: this page is under construction. Additional content and citations to be built out further)