‘Dunbar's number’ deconstructed

2021/05/01 by Patrik Lindenfors, Andreas Wartel, Johan Lind · 2 voices · 69 citations
Psychology · #Biology #Evolutionary Psychology and Human Behavior #Evolutionary biology #Primate Behavior and Ecology

paper · doi:10.1098/rsbl.2021.0158

published in Biology Letters 17(5), 20210158 (Royal Society)

openalex publication_date 2021/05/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/27

Abstract

A widespread and popular belief posits that humans possess a cognitive capacity that is limited to keeping track of and maintaining stable relationships with approximately 150 people. This influential number, 'Dunbar's number', originates from an extrapolation of a regression line describing the relationship between relative neocortex size and group size in primates. Here, we test if there is statistical support for this idea. Our analyses on complementary datasets using different methods yield wildly different numbers. Bayesian and generalized least-squares phylogenetic methods generate approximations of average group sizes between 69-109 and 16-42, respectively. However, enormous 95% confidence intervals (4-520 and 2-336, respectively) imply that specifying any one number is futile. A cognitive limit on human group size cannot be derived in this manner.

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Discussions

• "Dunbar's Number" is a zombie that lives forever in the science press it seems. Estimates of Dunbar's Number with 95% intervals, for a range of model specifications (from doi.org/10.1098/rsbl... ): [bsky, 67 points, 5 comments]
• dispute?🍿): https://doi.org/10.1098/rsbl.2021.0158 [bsky, 0 points, 0 comments]

Related

• The Social Brain
• Discrete hierarchical organization of social group sizes
• The human brain in numbers: a linearly scaled-up primate brain
• External measures of cognition
• Calling Dunbar's Numbers