the Grant Study at Harvard Medical School has been following a group of 268 men for over eighty years. The amount of data accumulated on them could fill rooms, and the insights about what makes for a long, happy life are plentiful. Yet when George Vaillant, who led the study for much of his own life, was asked what he learned from decades of studying these men, he replied with one sentence: That the only thing that really matters in life are your relationships to other people.
