Dunbar's number, in short, is the number of people with whom one person can maintain stable social relationships—relationships in which you know who each person is and how each person relates to every other person. Dunbar proposed that humans can only comfortably maintain about 150 stable relationships.
Here are five fascinating excerpts:
On the remarkable consistency of the number one-hundred-and-fifty –
"When Dunbar consulted the anthropological and historical record, he found... the average group size among modern hunter-gatherer societies was 148.4 individuals."
"Company size in professional armies... was also remarkably close to a hundred and fifty, from the Roman Empire to sixteenth-century Spain to the twentieth-century Soviet Union."
After examining the destinations of Christmas cards sent from households across the U.K., he found that "each individual’s network was composed of about a hundred and fifty people."
On what makes friendships strong –
"[O]ne of the things that keeps face-to-face friendships strong is the nature of shared experience: you laugh together; you dance together; you gape at the hot-dog eaters on Coney Island together. We have a social-media equivalent—sharing, liking, knowing that all of your friends have looked at the same cat video on YouTube as you did—but it lacks the synchronicity of shared experience. It’s like a comedy that you watch by yourself: you won’t laugh as loudly or as often, even if you’re fully aware that all your friends think it’s hysterical. We’ve seen the same movie, but we can’t bond over it in the same way."
On mastering social skills and abilities –
"We aren’t born with full social awareness, and Dunbar fears that too much virtual interaction may subvert that education. 'In the sandpit of life, when somebody kicks sand in your face, you can’t get out of the sandpit. You have to deal with it, learn, compromise,' he said. 'On the internet, you can pull the plug and walk away. There’s no forcing mechanism that makes us have to learn.' If you spend most of your time online, you may not get enough in-person group experience to learn how to properly interact on a large scale—a fear that, some early evidence suggests, may be materializing. 'It’s quite conceivable that we might end up less social in the future, which would be a disaster because we need to be more social—our world has become so large' Dunbar said. The more our virtual friends replace our face-to-face ones, in fact, the more our Dunbar number may shrink."
"In the sandpit of life, when somebody kicks sand in your face, you can’t get out of the sandpit. You have to deal with it, learn, and compromise. On the internet, you can pull the plug and walk away. There’s no forcing mechanism that makes us have to learn."
On the cost of large, online social networks –
"With social media, we can easily keep up with the lives and interests of far more than a 150 people. But without investing the face-to-face time, we lack deeper connections to them, and the time we invest in superficial relationships comes at the expense of more profound ones."
Without investing face-to-face time, we lack deeper connections, and the time we invest in superficial relationships comes at the expense of more profound ones.
On the importance of touch (and presumably other ways we communicate in face-to-face encounters) –
"'We underestimate how important touch is in the social world,' Dunbar said. With a light brush on the shoulder, a pat, or a squeeze of the arm or hand, we can communicate a deeper bond than through speaking alone. 'Words are easy. But the way someone touches you, even casually, tells you more about what they’re thinking of you.'"
If you're eager for more, here's a link.