People limited to 150 friends, despite Facebook, says academic

January 25, 2010 Human brains cannot manage more than 150 friendships – even with the advent of social networking websites like Facebook, Bebo and Myspace. This is the conclusion of Robin Dunbar, Professor of Evolutionary Anthropology at the University of Oxford. Dunbar originally carried out research in this area in the 1990s, looking at social groups from modern offices back to ancient villages. He found that the neocortex in the brain, used for thinking and language, cannot cope with more than 150 friends – a conclusion known as "Dunbar's number". Groups of people tend to be limited to about 150 as, beyond that, social cohesion suffers. Revisiting the topic, Dunbar's view is that this number has not increased even with online methods of keeping in touch with friends, like Facebook.

Dunbar compared the online activity of those with thousands of internet friends and those with hundreds, before concluding that there was no appreciable difference in their levels of activity. He defined a friend as someone that the individual cared about and made contact with at least yearly. "The interesting thing is that you can have 1,500 friends but when you actually look at traffic on sites, you see people maintain the same inner circle of around 150 people that we observe in the real world. [...] People obviously like the kudos of having hundreds of friends but the reality is that they’re unlikely to be bigger than anyone else’s", he observed.

Another conclusion of his study was that women were better at keeping friendships going on Facebook than men – "girls are much better at maintaining relationships just by talking to each other. Boys need to do physical stuff together". The full results of his study are due to be published later in 2010.

Dunbar, 52, has been an Oxford professor since 2007, having previously been Professor of Evolutionary Psychology at the University of Liverpool. He is a Fellow of the British Academy and a fellow of Magdalen College, Oxford.