Do you thrive within the crowds of a large metropolis or do you prefer the close community spirit of village life? Analyzing mobile communication data reveals how a person’s social network changes when moving from a small town into a big city. A team of researchers from both the MIT Senseable City Lab and the Santa Fe Institute worked with Orange Labs, British Telecom and Raschke Software Engineering to study how cities affect our social relationships.
Human interaction networks can be inferred from billions of anonymized mobile phone records. This study, focusing on Portugal and the UK, reveals a fundamental pattern: our social connections scale with city size. People who live in a larger town make more calls and call a larger number of different people. The scaling of this relation is 'superlinear,’ meaning that on average, if the size of a town doubles, the sum of phone contacts in the city will more than double – in a mathematically predictable way.
Surprisingly, however, group clustering (the odds that your friends mutually know one another) does not change with city size. It seems that even in large cities we tend to build tightly knit communities, or ‘villages,’ around ourselves. There is an important difference, though: if in a real village our connections might simply be defined by proximity, in a large city we can elect a community based on any number of factors, from affinity to interest to sexual preference.
The findings of this research help elucidate the role of cities as accelerators of human interactions, and the effectiveness of urban social space in the diffusion of ideas and information. Eventually, they can help us understand a broader spectrum of social phenomena, from crime to the spread of diseases.
Social networks derived from mobile phone data in Portugal.
For more information, see the published paper or the preprint.
You can also download the press release and the visual material.
The project was developed as part of Ericsson’s “Signature of Humanity” project.
† In this graph outliers are not considered to better show the increase in the average number of contacts.
‡ The graph only shows data from cities in Portugal.