What do the Rolling Stones, One Direction and Guns ‘n’ Roses have in common? The social brain hypothesis is a theory that states humans are capable of maintaining close relationships with no more than five people, of which all these bands are perfect examples.
A new study has recently been published that this rule may not only apply to international superstars, but to entire populations.
The concept behind this theory is that humans with their primate brains were able to handle living in large groups and having to interact and form relationships with a larger number of people. However, the closest of the relationships often come with a lot of emotional baggage, and so while you may have hundreds of “friends” on Facebook, we are only able to develop a limited number of intimate connections and the rest are merely acquaintances.
The study of social media data is a prime way to analyse the situation. By looking at Facebook and Twitter, researchers were able to construct a model for social networks, made up of four “Dunbar Layers”. The four layers represent the closeness of the connection. The innermost layer, according to the model, represents the person’s closest relationships, each person having an average of five other people in this layer. Each layer henceforth contains an increasing number of contacts, and as the quantity increases, the “closeness” of the relationship decreases. On average, this left people with about 150 people in a social network.
To further test this theory, a team of researchers (including the scientist, Robin Dunbar, who originally put forward the hypothesis) analysed every cell phone made in a European country during 2007. Using the length of the call between the two people as an indication of their closeness, they sought to fine whether the Dunbar Layers could be observed in the data.
The results were astoundingly similar to the findings from previous studies. Not only was it possible to recognise the layers in the interactions over the telephone, but also the number of people in these layers were also remarkable similar. People were found to have an average of 4.1 close friends, who they called most often. Three further layers of decreasingly close but increasingly numerous contacts were identified, with the average number of total people in the entire social network being 129.
These studies suggest that the Dunbar model is in fact able to model a representation of social networks of an individual. Although, there is no current explanation of why these structured layers form such a consistent pattern.
Nevertheless, the findings incorporate more stars such as the Power Rangers, the Jackson Five and the Backstreet Boys, which seems to confirm that five really is the perfect number to form a group.