---
type: source
title: "Neocortex size as a constraint on group size in primates"
author: "Robin Dunbar"
url: https://doi.org/10.1016/0047-2484(92)90081-J
date: 1992-06-01
domain: cultural-dynamics
format: paper
status: processed
processed_by: clay
processed_date: 2026-03-08
claims_extracted:
  - "human social cognition caps meaningful relationships at approximately 150 because neocortex size constrains the number of individuals whose behavior and relationships can be tracked"
tags: [dunbar-number, social-cognition, group-size, evolutionary-psychology]
---

# Neocortex Size as a Constraint on Group Size in Primates

Original paper establishing the correlation between neocortex ratio and social group size across primates, extrapolating ~150 as the natural group size for humans. Published in Journal of Human Evolution. Extended in Dunbar 2010 *How Many Friends Does One Person Need?*