Our Monkey Brain: Status Update

How many friends can a person really have? It’s a question I asked myself when I passed 400 friends on Facebook recently (Congratulations? Yes, thank you.). And it’s a question The Economist asked recently as well. One estimate, provided by Oxford anthropologist Robin Dunbar, is roughly 150. It’s been called Dunbar’s Number, and it’s based on the idea that a species’ ability to track social networks — who everyone is, who likes whom, who hates whom, who wants to mate with whom — is limited by the size of said species’ neocortex (the part of the brain involved in conscious thought).

Sure enough, the average network on Facebook is 120, roughly consistent with Dunbar. But there are also a lot of folks on Facebook with 500 or more people in their networks. What’s the deal with them?

Well, first, let’s go back to those 120-ers. Even with 120 people in one’s social network, Facebook’s in-house sociologist, Cameron Marlow, found that people only really interact with about seven people on average (seven for men, 10 for women). That’s how many people an individual might interact with by commenting on their photos or status updates. When it comes down to actual one-on-one interaction — as in, email exchanges or IM chats — those numbers fall even further. Four for men, six for women.

The 500-ers? They still only interact with a large handful: 17 for men, 26 for women; one-on-one communications with 10 for men, 16 for women. On average.

So, even with massive friends lists, our core social networks remain small. But we do appear to be seeing a permanent expansion of our peripheral social networks, which perhaps have a value of their own.

Image by ChrisL_AK via Flickr