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Human communities and ego-centric social networks have a distinct size that reflects a generic relationship between relative neocortex volume and social group size that is characteristic of primates in general (the social brain hypothesis). Human networks are structured into layers that reflect both differences in the frequency of contact and levels of emotional closeness. The rate of decay in the frequency of contact across network layers is very steep, and we might expect this to have a very significant effect on the likelihood of Ego finding out some novel fact when information flow is limited to face-to-face interaction. I use an analytical model parameterized by these contact frequencies to show that there may be little advantage in having a network larger than ~150 for the purposes of information exchange. I then present a Monte Carlo simulation model to show that structure significantly impedes the rate of information flow in structured communities. Copyright © The JOIE Foundation 2010.

Original publication




Journal article


Journal of Institutional Economics

Publication Date





345 - 371