Research suggests that more than our eating and exercise habits, our social lives can predict how long we’ll live

By

SUSAN PINKER

Jun. 25, 2015 14:53 p.m. ET

See the column on the Wall Street Journal site

Personal independence is such an iconic American value today that few of us question it. In previous generations, retirees lived with family, but now that a large swath of older people can afford to live on their own, that’s what they choose. The convenience of digital devices means that we can now work, shop and pay our bills online, without dealing directly with other people. According to the U.S. Census, 10% of Americans work alone in remote offices and over 13% live alone, the highest rate of solo living in American history.

But is this go-it-alone ideal good for us? New research suggests that, even if you enjoy being by yourself, it just might kill you—or at least shorten your life.

A team led by Julianne Holt-Lunstad at Brigham Young University showed that living alone, or simply spending a lot of your time on your own, can compromise your physical and psychological resilience—whether or not you like your solitude. Published in Psychological Science in March, their data show that how much real social interaction you get is a good predictor of how long you will live.

If you fit into one of three categories—living alone, spending much of your time alone or often feeling lonely—your risk of dying within the next seven years is about 30% higher than it is for people who are otherwise like you. Based on a meta-analysis comprising 70 studies and over 3.4 million adults, the team’s findings reinforce a growing consensus: In-person interaction has physiological effects.

Scientists have long known that loners are likely to die well before their more gregarious neighbors. A landmark longitudinal study published in the American Journal of Epidemiology in 1979 followed nearly every resident of a northern California town for nine years; its results showed that people who not only had intimate partners but met regularly with others to play bridge or volunteer at church were twice as likely to outlive those who led solitary lives. Still, critics wondered whether social contact was the key. Perhaps the social butterflies were healthier to begin with, or the more isolated people had hidden problems, such as depression or disability, that cut their lives short.

Dr. Holt-Lunstad’s team controlled for these confounding factors. What’s more, they discovered that the effect isn’t always a matter of preference or state of mind. We used to think that subjective experience was all that mattered. You could be single or married, spend your days alone or in a throng of people; if you often felt lonely, the thinking went, your blood pressure would spike and your immune function would suffer.

The new research found, however, that objective measures of the amount of human contact you get are as critical to your survival as your opinion of your social life. “I’ve spent almost my whole career studying social support, and I absolutely know the strong effects that our perceptions have on our physiology,” Dr. Holt-Lunstad told me. “But there are other determinants of health that are independent of our perceptions. Even if we hate exercise or broccoli, they’re still good for you.” Our intuitions don’t always point us in the right direction either, she added. “There are things that we enjoy greatly that are bad for our health, like eating those rich, fatty desserts or that big, juicy burger. We take great pleasure in things that are not that great for our health.”

In fact, in a study from 2010 in PLOS Medicine, Dr. Holt-Lunstad showed that our social lives are more faithful predictors of how long we’ll last than our eating and exercise habits.

We are still left with the why question. One piece of the puzzle has to do with hormones. Oxytocin and vasopressin are secreted when we are near enough to hug someone—even if we just shake hands. These hormones reduce stress, kill pain and allow us to let down our guard, all of which contribute to long-term resilience. Real encounters can also switch on and off genes that control our immunity and the rate of tumor growth. But it isn’t all about neurochemistry. As Dr. Holt-Lunstad notes, “just having someone around to call 911 can be a matter of life or death.”