Neocortex size as a constraint on group size in primates
Humans can maintain ~150 stable social relationships (cognitive limit)
Robin Dunbar's research on the relationship between neocortex size and social group limits provides the biological basis for understanding coalition size constraints. His discovery that humans can maintain approximately 150 stable social relationships (Dunbar's Number) explains why business coalitions face cognitive limits.
The chapter applies this research to show that for organizational coalitions, the effective limit is even lower (~15-20) because organizations are collections of people requiring more complex tracking. This explains why successful coalitions nearly all have ≤15 members (Airbus 4, early EU 6-12, functional OPEC core 8-12) while larger coalitions fail (OPEC+ at 23, WTO at 164).
Dunbar's work validates the chapter's recommendation to limit coalition size to 8-10 members unless heavy institutional infrastructure investment is possible.
Key Findings from Dunbar (1992)
- Humans can maintain ~150 stable social relationships (cognitive limit)
- Limit determined by neocortex size and reciprocity tracking capacity
- Business coalitions face lower effective limit (~15-20 organizational relationships)
- Beyond cognitive limit, indirect reciprocity and reputation systems required
- Primate coalitions cluster at 2-4 members; larger coalitions unstable