Revisiting Dunbar’s Number (and the rule of 150 relationships)

Today, it’s easier to find out what long-lost friends are doing when they post pictures of their trip to South America on Facebook than keeping up with a trusted buddy in the same town. The power of social networks to keep us close to people with whom we have weak ties can sometimes feel like a poor substitute for actually keeping touch with the people who matter most.

Yet a strange paradox happens when you think about the “go-to” people in your network for a given topic, subject, or interest. Even though you haven’t spoken to them for months or for years, they are the people who will write you back on social networks, call you when you call them, and offer the social glue that you need to support your network. Robin Dunbar – the anthropologist who invented “Dunbar’s Number,” or the observation that our networks tend to top out at about 150 people – believes that social networks have not fundamentally changed our ability to relate to each other in groups.

So should we revisit Dunbar’s Number? In my experience, the basic nature that Dunbar presents – that we are hardwired by biology to maintain a certain number of connections closely – seems true. Yet I’m not sure that Dunbar’s number, when applied to the various spheres in which we relate, has the same meaning in the age of the internet and in describing the ability that we have to form “loose ties” with people whom we meet on the internet. Consider this oddity – you may have met someone for the first time online who talks about some of the same things that you do, and later find that when you meet in real life that the connection you have feels like a “friend.”

The meaning of “friend” in a social media sense – clearly a range from an acquaintance to an actual close friend – is not exactly what Dunbar is getting at when he describes the size of social groups as defined by biology. Dunbar acknowledges that community size has grown over time, and I would argue that social networking has – for at least some of us – increased our Dunbar Number in ways we don’t yet understand.

When you think of the ability to reach out to people you know (either passably or reasonably well) on a given subject or topic and get a response, you realize that Dunbar’s Number may need rethinking. Here’s a proposal: that all of us support multiple sets of “Dunbar Number” communities around our homes, our schools, our workplaces, and our interest. The connections made easier by the Internet have exposed the weak ties between each node in our disparate networks – or between the connectors that tie together those nodes into a sort of edge social graph – and made it easier for us to find the communities that matter around the interests that we have. Even if we haven’t met the 150 people who share our affinity to Pez dispensers (and who would be in our Dunbar Number if they lived closer to us), we can meet and form the similar relationships that would be closer if we lived near them. Dunbar is right in that we can keep up only some close relationships at any one time, but technology has made it possible for us to simultaneously live in many communities at once.

We may only have 150 people in our immediate Dunbar sphere as we perceive it, and our ability to reach out and find the other kindred spirits (some of whom we may come to know well) causes our overall useful universe to grow. How much does it grow? For most people, not to the 10x point of the Dunbar Number. But many super connectors who I’ve met really are able to keep up relationships with a larger group than the 150 that Dunbar posits. The size of the brain that we have doesn’t change, but the technology to augment that brain is growing in ways that we don’t understand yet. Does this change your hard wiring? Maybe. And we’re going to find out over the next several years or decades as social networking and wearable computing become more ubiquitous.