The Harvard Study of Adult Development is an 84-year longitudinal study that has tracked the lives of over 700 men since 1938. It was started by researchers who wanted to understand what factors contribute to a fulfilling and healthy life. The study has found that good relationships are the single most important factor for happiness and wellbeing.

The study began with two separate groups - 268 Harvard sophomores and 456 disadvantaged inner-city boys from Boston. The groups were later combined into one study that followed participants across their entire adult lives. Extensive data has been collected through interviews, questionnaires, medical records and more.

One of the key findings is that people who have warm, satisfying relationships are happier and live longer than those who are more isolated. The quality of relationships matters more than the quantity. Even unhappy marriages can negatively impact health. People who were satisfied with their relationships at age 50 were the healthiest at age 80. Relationships act as a protection against the hardships of life.

This finding mirrors ancient wisdom - philosophers and religions for thousands of years have promoted the idea that good relationships are fundamental to human flourishing. Although culture and technology change rapidly, the basic human need for connection endures.

The study confirms that it's never too late to improve relationships and increase happiness. Our childhoods shape us but don't define our fate. With effort, people can increase their social connections at any age.

The Harvard Study and similar longitudinal studies provide a rare window into entire lives over time. By following individuals from youth to old age, we can discover patterns and predictors of wellbeing that aren't apparent in short-term studies. The lives of the study participants demonstrate that the good life is complicated but within reach for all of us. It starts with nurturing our relationships.