Dunbar's Layers (5-15-50-150)

Biological Parallel

Chimpanzee social networks exhibit nested layers: 5 core grooming partners (daily contact), 15 close allies (weekly interaction), 50 community members (monthly encounters), 150 recognized individuals across neighboring territories. Each layer correlates with neocortex processing capacity—grooming time, coalition memory, and facial recognition create hard limits. Dunbar mapped these primate structures onto human organizations, revealing that our Stone Age social brain still governs modern corporate hierarchies.