Sapiens: A Brief History of Humankind · chapter 2 · id sapiens-c2-02-dunbars-number----150----repre
“Dunbar's number -- 150 -- represents the maximum number of individuals a human can maintain stable social relationships with, constrained by neocortex size.”
TRUE, BUTconfidence: medium⚠ extracted by pipeline, re-audit pending
Receipts
Dunbar (1992), Journal of Human Evolution 22(6):469-493DOI registry: valid
Extrapolating from the correlation between neocortex ratio and mean group size in nonhuman primates predicts a 'natural' human group size of approximately 148, rounded to 150.
Lindenfors et al. (2021), Biology Letters 17(5):20210158DOI registry: valid
Using Bayesian methods on the same primate brain data, the 95% confidence interval for predicted human group size ranges from approximately 2 to 520. The data cannot reliably predict a specific number like 150.
De Ruiter et al. (2011), American Anthropologist 113(4):557-568DOI registry: valid
The brain-based prediction method is unreliable for pinpointing a specific number. Dunbar's number should be treated as a rough heuristic, not a precise biological limit.
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