Yes, there’s scientific research on that too.
For many of us, the top of our life priority list might look something like this: family, work—maybe exercise. Time with friends can sometimes end up near the bottom.
That’s a mistake, says Lydia Denworth, a science journalist and the author of the new book “Friendship,” which was published last month by W.W. Norton & Co. Ms. Denworth interviews animal biologists studying baboons and rhesus macaque monkeys, anthropologists and neuroscientists to uncover just how important friendship is not only for happiness and emotional health, but, she argues, physical health, too. In fact, friends are key to our very survival, Ms. Denworth asserts.
Here are edited excerpts from an interview.
What does studying how animals relate to each other tell us about human friendships?
At its simplest, it’s just how critical quality social bonds and friendships are. In animals, the big measures that evolutionary biologists study are reproductive success, which they count as either how many babies you have or how long those babies live, and longevity, or how long you survive. Nonhuman primates have very structured hierarchies that they exist in, and everyone assumed that that must have more importance for how long you live and how many babies you have and how healthy they are. And it wasn’t. The most important thing was the strength of the social bonds, how positively and well and regularly an individual animal interacted with other animals. Scientists really couldn’t believe it.
How does friendship affect physical health?
Friendship literally improves your body’s cardiovascular functioning, how your immune system works, how you sleep. You can imagine the food you put in your body makes you healthy or not. But sitting in a coffee shop with someone and just chatting about what’s going on with your life, we always thought emotionally that made you feel good. But actually it really is doing much more.
A big study at Harvard of men across their lives from 20 to 80 found that the single best predictor of your health and happiness at 80 was not your wealth or your professional success. It was your relationships at 50.
What makes a good friendship?
The simple definition that biologists use is a friendship is positive, it makes you feel good, it is long-lasting and stable and it has reciprocity and cooperation in it. So there’s a little give and take. Friendship is about setting up your life so you have people you can rely on when you need them. Literally, it was for when the lions came hunting for your friends. Baboons and monkeys do better when they are together. It’s why humans were never really alone.
There’s not one way to do friendship. Some people are introverts and that’s fine. The difference between not having any close friends and having one is enormous in terms of your emotional health and physical health. Quality matters so much more than quantity. Most people only have an average of four really close friends.
Why do we become friends with one person and not another?
There’s this interesting chemistry to friendship. Just like in romance, you are more drawn to some people than you are others. Some of it is very straightforward: You are interested in the same things, you spend time in the same place. That’s one reason why we are close to relatives, because you have a head start, you spend more time with them than you do anyone else. We do tend to be better friends with people who are more like us.
Having a shared world-view turns out to be important. Scientists looked at all these people in a social network, showed them the same sets of videos and looked at how their brains responded to these videos. They could predict just by looking at the brain processing who was friends with whom. Literally, you hear and see the world more like the people you are friends with. The big question is: Is it cause or effect? Are you drawn to people who already see and process the world more similarly from the start or do you become more similar? Of course, as with so many things, the answer is probably both.
What impact is digital communication and social media having on friendships?
With relationships, it usually is net positive. One reason is just because people who are active on social media tend to have wider, bigger, more diverse social networks. What the research is showing is we tend to use social media as just an extra way to communicate with your good friends. And older adults, relationally, they absolutely benefit from social media because they have a harder time getting out or getting around or they’re further from their families. It really has opened up a new channel for people.
That doesn’t mean if you only operate online, you get all those benefits. You don’t. You need a lot of face-to-face time to get the health benefits. But it’s just not true that being online is automatically this big negative. The people for whom social media has a clearer negative effect seem to be people who are already suffering from depression maybe or loneliness.