The key to survival: Find five people. Hold them close.

Close relationships—about five of them—are as essential as food and water, according to this author
(Illustration by Alisha Davidson)

Loneliness kills, and friendship preserves. There’s really nothing else—not exercise or even quitting smoking—that matches the positive effect on mental and physical health of having friends, writes the inventor of “Dunbar’s number” in Friends: Understanding the Power of Our Most Important Relationships. Quite simply, he says, friendship is “the best predictor of your chances of surviving from this moment into the future.”

Over a quarter-century ago, Robin Dunbar, the British psychologist who now heads Oxford’s Social and Evolutionary Neuroscience Research Group, established his famous cognitive limit to the number of people—150, give or take—with whom anyone can maintain stable social relationships. In his new book, Dunbar concentrates on humans’ inner circles to understand how those close friendships are made and how they differ in composition by family circumstance, age, gender and culture, while still almost universally capping out at another stable number—five.

By “friends,” says Dunbar in an interview, he means close relationships. “For most of us, the inner five, the shoulders-to-cry-on friends, are made up of two friends plus two extended family members, with the fifth sometimes [being] a friend and sometimes kin.”

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At 74 and deeply embedded in a globe-spanning web of former grad students and post-doctoral associates, Dunbar can cite reams of evidence to support his thesis about the importance of friendship, which the era of Big Data helped him arrive at. “It’s extraordinary,” he exclaims, “what you can learn from phone records.” In one study, some 18-year-olds—just entering into the “churn” years of their lives, when about 40 per cent of their relationships will change as they enter university or the workplace—were sending over 100 texts a day. The frequency and length of messages to new friends replaced, almost exactly, the attention once paid to others.

Dunbar points to an important difference between the kith and the kin in our social networks. Family is simply there, usually from birth, and is capable of withstanding long periods of neglect, benign or otherwise, without loss of a mutual sense of obligation—what Dunbar calls “the kinship premium.” Friends require hard work to gain and keep. A solid “30 minutes a day on average,” says Dunbar, which is why intimates are so few in number: “The main issue is the sheer amount of time involved,” he says. Distance can actually make the heart grow fonder in regards to family—who can be as annoying as they are dependable—but stretching available time beyond its breaking point tends to destroy friendships.

Although Dunbar believes the evidence shows a “striking sex difference” in the intensity of friendships—with women’s bonds being more fervid—both sexes find that distance simply cannot be bridged by electronic communication. “There is something deeply engaging,” says Dunbar, “about eye-to-eye across the kitchen table—and the ability to touch.”

Susan Pinker, whose book The Village Effect: How Face-to-Face Contact Can Make Us Healthier and Happier has seemed ever more prescient since its 2014 publication, completely agrees. “In-person contact is essential for touch or non-verbal communication, that little pat on the arm,” says the Montreal-based developmental psychologist. Getting together signals “you’re willing to invest the time,” she adds, a calculus we all subconsciously register. “If you don’t sustain a friendship, then it melts away—unless it’s with your intimate family members.”

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Of all the lockdown workarounds for the rituals and emotions of friendship as we knew it before COVID-19, only pets—whose ownership spiked during the lockdowns—offered the possibility of touch, says Pinker, the happy owner of a pandemic puppy: “a big, hairy baby who needs attention and more haircuts than I get.”

Both psychologists see the pandemic as a real-world experiment in how friendship may evolve. Dunbar is cautiously awaiting the results of studies into the corroding effects of isolation, while Pinker is optimistic the lockdowns have acted as a wake-up call. “Before the pandemic, I think there were still a lot of people thinking, ‘Skype, FaceTime, I don’t really need to go out and do this personally.’ Now we all know we need to.” And both, too, know further changes in our social relationships, unrelated to social media or epidemics, are on the horizon. For about a century, Dunbar notes, the Western world has held at about half-family and half-friend in its social circles, down from what was almost entirely family not that far back in history. With families continuing to shrink, so too will the kin share of our inner circles. We are all going to need more friends.

This article appears in print in the March 2022 issue of Maclean’s magazine with the headline, “The BFF quotient.” Subscribe to the monthly print magazine here.