Dunbar’s Circles Get a Mathematical Explanation
Researchers at the Moscow Institute of Physics and Technology (MIPT) have developed a mathematical model describing how stable social ties form. The university announced the findings on the Naked Science website.
According to anthropologist Robin Dunbar’s theory, people can maintain stable relationships with only a limited number of individuals. The innermost circle of close friends typically consists of five people, while the total number of people we interact with regularly is around 150.
The model does not impose this structure in advance. When a problem arises, an individual randomly chooses an acquaintance to ask for help. If the help is successful, that social tie grows stronger, while others weaken because of limited cognitive resources. This process gradually produces concentric circles. When the probability of refusal is zero, the individual always chooses the same acquaintance.
As Alexander Gubanov, an assistant lecturer in MIPT’s Faculty of Applied Mathematics and Computer Science, explained, a person assesses the difficulty of a task, considers which social ties are strong enough, and randomly selects one of them.
The study was published in the journal Social Networks.
