Topic for Apr. 19. ( Fri )

[Alex !]

Dunbar's number: Why we can only maintain 150 relationships

-posted on bbc.com

According to Dunbar’s theory, people can ‘handle’ up to about 150 relationships – whether in early hunter-gatherer societies or the modern workplace.

The theory of Dunbar’s number holds that we can only really maintain about 150 connections at once. But is the rule true in today’s world of social media?

If you’ve ever been romantically rejected by someone who just wanted to be friends, you may have delivered a version of this line: “I’ve got enough friends already.” Your implication, of course, being that people only have enough emotional bandwidth for a certain number of buddies.

It turns out that’s not just an excuse. There are well-defined limits to the number of friends and acquaintances the average person can retain. But the question about whether these limits are the same in today’s digital world – one in which it’s common to have social media profiles, or online forums, with thousands of followers – is more complicated.

According to British anthropologist Robin Dunbar, the “magic number” is 150. Dunbar became convinced that there was a ratio between brain sizes and group sizes through his studies of non-human primates. This ratio was mapped out using neuroimaging and observation of time spent on grooming, an important social behaviour of primates.

Dunbar concluded that the size, relative to the body, of the neocortex – the part of the brain associated with cognition and language – is linked to the size of a cohesive social group. This ratio limits how much complexity a social system can handle.

Dunbar and his colleagues applied this basic principle to humans, examining historical, anthropological and contemporary psychological data about group sizes, including how big groups get before they split off or collapse. They found remarkable consistency around the number 150.

According to Dunbar and many researchers he influenced, this rule of 150 remains true for early hunter-gatherer societies as well as a surprising array of modern groupings: offices, communes, factories, residential campsites, military organisations, 11th Century English villages, even Christmas card lists. Exceed 150, and a network is unlikely to last long or cohere well. 

According to the theory, the tightest circle has just five people – loved ones. That’s followed by successive layers of 15 (good friends), 50 (friends), 150 (meaningful contacts), 500 (acquaintances) and 1500 (people you can recognise). People migrate in and out of these layers, but the idea is that space has to be carved out for any new entrants.

Dunbar isn’t sure why these layers of numbers are all multiples of five, but says, “this number five does seem to be fundamental to monkeys and apes in general”. Of course, all of these numbers really represent range. Extroverts tend to have a larger network and spread themselves more thinly across their friends, while introverts concentrate on a smaller pool of “thick” contacts. And women generally have slightly more contacts within the closest layers.

What determines these layers in real life, in the face-to-face world… is the frequency at which you see people,” says Dunbar. “You’re having to make a decision every day about how you invest what time you have available for social interaction, and that’s limited.

Although there are many factors that can limit the number of relationships that we create and maintain, these studies help us to better understand… and measure such variables’ influence.

For instance, if someone is wealthy enough to hire assistants to partly manage their relationships – or to outsource some of the emotional labour to others – they might be less constrained by the number of relationships they can comfortably maintain. As in so many aspects of social life, the super-connected are the super-privileged.

Dunbar’s number may be most applicable for premodern societies or for middle-income groups in contemporary Western societies. But even these are becoming more complicated, due to the way internet culture is transforming relationships.

When people have more than 150 friends on Facebook or 150 followers on Twitter, Dunbar argues, these represent the normal outer layers of contacts (or the low-stakes connections): the 500 and 1500. For most people, intimacy may just not be possible beyond 150 connections.

It makes sense that there’s a finite number of friends most individuals can have. What’s less clear is whether that capacity is being expanded, or contracted, by the ever-shifting ways people interact online.

There’s some truth to the idea that there’s only really so much information you can keep in your head… so many avatars. The more you know about someone, I think the better that relationship is, but probably also limits the number of relationships you can have.

Having a conversation isn’t like a lighthouse; it is not just blinking away out there and maybe someone is listening, and maybe somebody is not. In this view, the non-physical, non-real-time nature of internet relationships means that they can’t challenge “real-world” ones in meaningful ways. Face-to-face relationships, with all the non-verbal information that is so critical to communication, remain paramount.