All of these studies, as well as our own Harvard Study, bear witness to the importance of human connections. They show that people who are more connected to family, to friends, and to community, are happier and physically healthier than people who are less well connected. People who are more isolated than they want to be find their health declining sooner than people who feel connected to others. Lonely people also live shorter lives. Sadly, this sense of disconnection from others is growing across the world. About one in four Americans report feeling lonely—more than sixty million people. In China, loneliness among older adults has markedly increased in recent years, and Great Britain has appointed a minister of loneliness to address what has become a major public health challenge.

This analysis echoes the findings of the study highlighted in the article in Science: across all age groups, genders, and ethnicities, strong social connections were associated with increased odds of living longer. In fact, Holt-Lunstad and her colleagues quantified the association: incredibly, social connection increased the likelihood of surviving in any given year by more than 50 percent. Across all of these studies, the mortality rate of individuals with the fewest ties was between 2.3 (men) and 2.8 (women) times higher than that of individuals with the most ties. These are very large associations, comparable to the effect of smoking on getting cancer. And smoking, in the United States, is considered the leading cause of preventable death.

The same is true for social fitness.

It’s not easy to take care of our relationships today, and in fact, we tend to think that once we establish friendships and intimate relationships, they will take care of themselves. But like muscles, neglected relationships atrophy. Our social life is a living system. And it needs exercise. You don’t have to examine scientific findings to recognize that relationships affect you physically. All you have to do is notice the invigoration you feel when you believe someone has really understood you during a good conversation, or notice the tension and distress after an argument, or the lack of sleep during a period of romantic strife.

Here is where Emmy Werner’s research, our own Harvard Study research, and many other pieces of research from across cultures and populations converge to show that a critical link between childhood experience and positive adult social connections is our ability to process

emotions.

It is from our relationships as children—especially our relationships with our family—that we first learn what to expect from others. This is when we begin to develop the emotional habits, so to speak, that will be with us for the rest of our lives. These habits often define the way we connect to others and our ability to engage others in mutually supportive ways.

A crucial point here is that our ability to process emotions is malleable. In fact, managing emotions is one of the things we actually get better at as we grow old. And there is strong evidence that we don’t have to wait until late in our lives for this to happen. With the right guidance and some practice, we can learn to be better at managing our feelings at any age.

What role did friendships play amid these challenges? Do their experiences have any lessons for us?

They do. Using participants’ firsthand accounts of their combat experiences and their connections to fellow servicemen, we found that those men who had more positive friendships with their fellow servicemen, and who served in combat units that were more cohesive and connected, were less likely to experience symptoms of PTSD after the war. Their friendships, in other words, were like a kind of protective armor. Having good and trusted friends buffered these men during some of the most difficult events of their lives.