Is Dunbar's Friend-Limiting Number Still Relevant in the Facebook Era?

Nineteen years ago, a British anthropologist took control of my social life. Robin Dunbar - he's the guy - said I could only have 150 friends.

Technically "Dunbar's number," a theoretical limit that pegs the number of social relationships one can maintain at somewhere between 100 and 230, applied to everyone, but I couldn't help but take it personally.

Fast forward to late 2011. I had more than 2,000 Facebook friends. I'd singlehandedly disproved the Brit's sociological theorem. Did I interact with every one of those 2,000 people? No. But they showed up in my News Feed. And wasn't that enough?

Not for Dunbar, apparently. He was looking for individual interactions. Well, I thought, if that's all it takes to disprove Dunbar's number, then that's what I'll do: I'll write personal letters to every one of my 2,000 Facebook friends.

Starting at A

I tackled the list alphabetically and kept the letters short. I don't write long letters to my best friends, so why pour my heart out to the casual ones? Concise, friendly, honest and personal - that was the goal.

A.S., a girl I dated in Chicago, was engaged now. So I sent her a congratulatory note. A.J. Jacobs, a fellow "stunt journalist," got a note explaining that I was sending letters to each of my Facebook friends.

"I look forward to the letter!" came the response.

"That was the letter," I clarified.

"I was expecting something handwritten. Something with nice calligraphy and a wax seal on the envelope," Jacobs said.

Clearly the guy was shilling for Dunbar, so I moved on.

I went to high school with A.G. He was a bully and I only accepted his Facebook friend request so I could monitor how miserable his life had become. The weight gain, the receding hairline, the recent breakup, the unemployment - just delightful. What friendly words did I have for him? None. So I de-friended him.

I'd forgotten so many A's in the past decade: The girl who advised the MSU Freshman Class Council, the guy from the ironic heavy metal band, the girl who requested my friendship after seeing a photo of me wearing a fake muscle suit. Needless to say, they were all pretty surprised (and confused) to hear from me.

And then I made it to the B's.

B.M., it turns out, is dead. It took me a while to realize this. Friends were still uploading photos of him and leaving comments on his page, like, "I miss you." At first, I figured he'd moved out of the country.

I wrote B.S. a long, apologetic note. I'd treated him rudely when we first met. A mutual "friend" of ours had said some pretty nasty things about him, but that "friend" turned out to be full of shit. B.S. accepted my apology.

Before I hit the C's, I made an executive decision: I was going to start leaving wall posts in place of writing letters. For some people, not all. That's what I do with my best friends, I figured. And wall posts are still personalized.

If it was somebody's birthday, they got a "Happy Birthday." If somebody's birthday had recently passed, well, they got a "Happy Birthday," too. And if somebody's birthday had passed by a couple weeks, they got a "Sorry I missed your birthday!" So maybe they're not as personalized, I thought. But 2,000, in case you haven't heard, is a huge number.

Some random observations from the C's through I's:

  • C.L.'s 6-month-old child had recently passed. I gave her my condolences. Truth is, I had no clue who this woman was. But my sentiments were real.
  • When I saw C.J., I thought, Who's the old guy? Is he a friend of my parents? And then I saw that C.J. was born in '83. Meaning he's younger than me.
  • After I wrote Dvn Yan Kit, I assumed I'd completed the D's. But apparently I have a Facebook friend named "Dyke Stabler," too.
  • Two of my middle-school friends got married, to each other. Recently. And I wasn't invited to the wedding.
  • Three years back, I asked this cute girl, K.C., if she could come to my party. She said that she couldn't because her parents had gotten in a big fight. "And it now is just a crazy mess," she wrote. I'd never written her back. So I asked whether the fight had ever been resolved. "My mom died, I got married, and I moved to Texas," came the response.

Enter Timeline

Before I hit the J's, I converted to Facebook's Timeline. As a result, I lost access to the alphabetical friend list, which brought my social experiment to a screeching halt.

I only made it through 1,000 of my 2,000 Facebook friends. But that was enough. My experiment's outcome was crystal clear: Dunbar's number kicked my ass.

In trying to disprove Dunbar's number, I actually proved it. I proved that even if you're aware of Dunbar's number, and even if you set aside a chunk of your life specifically to broaden your social capital, you can only maintain so many friendships. And "so many" is fewer than 200.

Writing my Facebook "friends" had taken over my time. I was breaking plans with real friends to send meaningless messages to strangers. Some of the strangers didn't respond, and many of those who did respond only confirmed Dunbar's theory.

Quick examples: When I wrote A. F., a Malaysian magician, he responded: "hey rick i think you might've sent me this message by mistake lol." And when I wrote A.D., a friend of a friend, and asked how things were going, she replied, "Sorrx but do i know you?:)"

I walk away from this experiment with a newfound respect for 1) British anthropology and 2) My real friends. There aren't too many of them, I now see. So I better treat them well.


Is Dunbar's Friend-Limiting Number Still Relevant in the Facebook Era? Wired.com has been expanding the hive mind with technology, science and geek culture news since 1995.