Dunbar’s number: 150 friends is our limit

It seems like it is pretty easy to collect hundreds of friends on Facebook. Between people we know from years of schools plus jobs plus other activities, the number can increase quickly. But having a large number of online “friends” goes against Dunbar’s number:

Most of Dunbar’s research has focused on why the GORE-TEX model was a success. That model 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…

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 goes on to suggest that larger organizations then have to find ways to create smaller groups where people can still maintain connections with others.

I’ve thought for a while that Facebook should move away from saying that all people you are connected to are “friends.” This indicates a closeness that I suspect doesn’t really exist in many of these online relationships. They are probably more like “acquaintances” or “people you have interacted with.” But, imagine what would happen if someone you thought was a friend marks you an acquaintance or vice versa. Additionally, by calling everyone a friend, you are suggesting that you are open to a broader set of relationships and Facebook is interested in bringing more people together. If we wanted to get more sociological, we might call these “strong” and “weak” ties but this seems fairly impersonal.

Figures from a few years ago suggested that people had an average of 120 Facebook friends. This still seems like a lot even as sociological research from 2006 (read the full study here) suggests that Americans have fewer confidants and less contact with existing confidants:

In 1985, the average American had three people in whom to confide matters that were important to them, says a study in today’s American Sociological Review. In 2004, that number dropped to two, and one in four had no close confidants at all…

The percentage of people who confide only in family increased from 57% to 80%, and the number who depend totally on a spouse is up from 5% to 9%, the study found. “If something happens to that spouse or partner, you may have lost your safety net,” Smith-Lovin says.

Here are two tentative hypotheses regarding this data:

1. Younger Facebook users are more likely to have higher numbers of friends. This seems to be driven by being students in high school and college where it is common to friend lots of people across a broad swath of classroom, social activity, and living situations.

2. Older Facebook users are more uncomfortable with the term “friends” to describe online relationships. Of course, as the younger generation ages and is used to such terms, the term will become more normal.

2 thoughts on “Dunbar’s number: 150 friends is our limit

  1. Pingback: Trying to disprove Dunbar’s number on Facebook | Legally Sociable

  2. Pingback: The Internet and social media can help us see more small things but the bigger picture is still fuzzy | Legally Sociable

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