Six degrees of separation why it is a small world after all

It’s a small world after all – and now science has explained why.

A study conducted by the University of Leicester and KU Leuven, Belgium, examined how small worlds emerge spontaneously in all kinds of networks, including neuronal and social networks, giving rise to the well-known phenomenon of "six degrees of separation".

Many systems show complex structures, of which a distinctive feature is small-world network organization. They arise in society as well as ecological and protein networks, the networks of the mammalian brain, and even human–built networks such as the Boston subway and the World Wide Web.

Recently published in Scientific Reports by an international team of academics from our Department of Mathematics and KU Leuven, the research showed that these remarkable structures are reached and maintained by the network diffusion, i.e. the traffic flow or information transfer occurring on the network.

The research presents a solution to the long-standing question of why the vast majority of networks around us (WWW, brain, roads, power grid infrastructure) might have a peculiar yet common structure: small-world topology. The study showed that these structures emerge naturally in systems in which the information flow is accounted for in their evolution.