By National Public Radio, 6/5/11
Most of Dunbar’s research … is based on the idea that human beings can hold only about 150 meaningful relationships in their heads. Dunbar has researched the idea so deeply, the number 150 has been dubbed “Dunbar’s Number.”
Ironically, the term was coined on Facebook, where 150 friends may seem like precious few.
“There was a discussion by people saying ‘I’ve got too many friends — I don’t know who half these people are,'” Dunbar says. “Somebody apparently said, ‘Look, there’s this guy in England who says you can’t have more than 150.'”
Dunbar has found 150 to be the sweet spot for hunter-gatherer societies all over the world. From the Bushmen of Southern Africa to Native American tribes, a typical community is about 150 people. Amish and Hutterite communities — even most military companies around the world — seem to follow the same rule.
The reason 150 is the optimal number for a community comes from our primate ancestors, Dunbar says. In smaller groups, primates could work together to solve problems and evade predators. Today, 150 seems to be the number at which our brains just max out on memory…
…Dunbar says there are some neurological mechanisms in place to help us cope with the ever-growing amount of social connections life seems to require. Humans have the ability, for example, to facially recognize about 1,500 people. Now that would be an impressive number of Facebook friends.
Yet the problem with such a large number of “friends,” Dunbar says, is that “relationships involved across very big units then become very casual — and don’t have that deep meaning and sense of obligation and reciprocity that you have with your close friends.”
One solution to that problem, he adds, can be seen in the modern military. Even as they create “supergroups” — battalions, regiments, divisions — most militaries are nonetheless able to maintain the sense of community felt at the 150-person company level.
“The answer has to come out of that,” Dunbar says, “trying to create a greater sense of community.
“In a way, Americans are lucky in that respect,” he adds. “There’s this long tradition of commitment to ideals that binds Americans together. That isn’t always true elsewhere.”
While modern society does make it hard to hang on to friends who aren’t geographically close, Dunbar says, his research shows family is different.
“Friends, if you don’t see them, will gradually cease to be interested in you,” he says. “Family relationships seem to be very stable. No matter how far away you go, they love you when you come back.”