Mind & Body

Despite Social Media, You Can Only Have 150 Friends at a Time

Humans are limited creatures. We have imperfect eyes and memories. We're such creatures of habit that we only regularly visit 25 places. And despite some of our four-figure Facebook friend counts, we only really have the capacity to maintain 150 friendships at a time.

Related Video: How Many Friends Can You Have?

Dunbar's Number

Robin Dunbar, an anthropologist and psychologist at the University of Oxford, has long argued that humans can only really have 150 friends at a time. (By "friends," here, he means casual friends — people you'd invite to a big party, not people you'd introduce to your mom.) At this point, 150 is widely known as "Dunbar's number."

It might be more accurate to talk about Dunbar's numbers, though. As Dunbar details in his TED Talk, the typical person has 150 casual friends at any given time, but within that 150, there are various levels of intimacy: about 50 medium-close friends, 15 friends you can rely on for emotional support, and five intensely intimate friends — or four, if you have a romantic partner. (A romantic partner takes up the bandwidth of two close friends.)

But hold on — plenty of people have more than 150 Facebook friends. Dunbar, for his part, argues those "friendships" lack substance. You might like all your friends' selfies from time to time, but you don't stay in touch with them in a meaningful way. They're really acquaintances, if that. They're "friends" only in the sense that that's what Facebook connections are called.

A point in Dunbar's favor: Across cultures, communities of 150 tend to thrive. The founder of GORE-TEX, a waterproof apparel company, found that his factories ran best with 150 employees — any more than that, and employees lost track of who did what job, creating inefficiencies. It's also common for military companies and other close-knit communities, like Native American tribes and Amish villages, to have 150 members.

Even on Facebook, where you certainly know someone with 1,000 friends, the most common number of friends is about 120 or 130, according to Dunbar. Pretty close to 150, huh?

Why Not More?

Thanks to the internet, we can now get to know basically anyone, anywhere in the world. In other words, modern life has radically expanded our pool of potential friends. So why has our number of actual friends held steady?

Dunbar's argument goes like this: While you could, theoretically, start a friendship with basically anyone, you don't have the resources to maintain friendships with more than 150 people at a time. Friendships, you see, rely on two finite resources: your mental capacity and your time.

You process your social relationships in a specific part of your brain — it's where you store all the information that adds up to intimacy with your friends. You can't cram an infinite number of complex relationships in there; it only has so much capacity for connections, and that maxes out at roughly 150 friends.

There are also only 24 hours in a day, and friendships require time, too. When you spend more time with a friend than usual, you typically grow closer to them; spending less time with them, on the other hand, means the relationship decays. Because quality time is essential to closeness, your capacity for closeness with others is limited.

That might sound sad and restrictive, but it doesn't have to be. Really, it's just a restatement of what we already know: life is short, and you can't do everything or befriend everyone. Instead, you have to use the time and mental energy you have wisely. Maybe we should all be throwing more big parties, too — so we can keep in touch with all 150 of our friends.

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Hear it from the horse's mouth in "How Many Friends Does One Person Need? Dunbar's Number and Other Evolutionary Quirks" by Robin Dunbar. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Mae Rice November 20, 2018

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