Journal of Institutional Economics

Research Article

Constraints on the evolution of social institutions and their implications for information flow

R. I. M. DUNBARa1 c1

a1 British Academy Centenary Project, Institute of Cognitive and Evolutionary Anthropology, University of Oxford, Oxford, UK


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.

(Online publication August 16 2010)


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RD's research is funded by the British Academy Centenary Research Project, the EPSRC/ESRC-funded TESS Project, the EU-FP7 SocialNets Project and the EU-FP7 ICTe-Collective Project. The Monte Carlo cultural transmission model of was developed by Chris Lowen while employed on a project grant to RD as part of the ESRC's ‘Economic Beliefs and Behaviour’ programme, and formed part of the output of the ESRC's Research Centre in Economic Learning and Social Evolution (ELSE). I thank Richard Sosis for providing his dataset on American utopian cults used in .