Discrete hierarchical organization of social group sizes

Zhou, W.X.; Sornette, D.; Hill, R.A.; Dunbar, R.I.M.

Abstract

The ‘social brain hypothesis’ for the evolution of large brains in primates has led to evidence for the coevolution of neocortical size and social group sizes, suggesting that there is a cognitive constraint on group size that depends, in some way, on the volume of neural material available for processing and synthesizing information on social relationships. More recently, work on both human and non-human primates has suggested that social groups are often hierarchically structured. We combine data on human grouping patterns in a comprehensive and systematic study. Using fractal analysis, we identify, with high statistical confidence, a discrete hierarchy of group sizes with a preferred scaling ratio close to three: rather than a single or a continuous spectrum of group sizes, humans spontaneously form groups of preferred sizes organized in a geometrical series approximating 3–5, 9–15, 30–45, etc. Such discrete scale invariance could be related to that identified in signatures of herding behaviour in financial markets and might reflect a hierarchical processing of social nearness by human brains.

Citation

Zhou, W., Sornette, D., Hill, R., & Dunbar, R. (2005). Discrete hierarchical organization of social group sizes. Proceedings of the Royal Society B: Biological Sciences, 272(1561), 439-444. https://doi.org/10.1098/rspb.2004.2970

• Journal Article Type: Article
• Publication Date: Feb 1, 2005
• Deposit Date: Jun 1, 2007
• Journal: Proceedings of the Royal Society B: Biological Sciences
• Print ISSN: 0962-8452
• Electronic ISSN: 1471-2954
• Publisher: The Royal Society
• Peer Reviewed: Peer Reviewed
• Volume: 272
• Issue: 1561
• Pages: 439-444
• DOI: https://doi.org/10.1098/rspb.2004.2970
• Keywords: Social brain hypothesis, Social group size, Log-periodicity, Fractal analysis.
• Public URL: https://durham-repository.worktribe.com/output/1629986