Two-Pizza Rule

Biological Parallel

Dunbar's number predicts cognitive limits on social group size—around 150 for humans, based on neocortex ratio. Beyond this, relationships become transactional rather than trust-based, coordination costs spike, and cheater detection fails. Primate troops exceeding species-typical sizes fragment because grooming time can't maintain cohesion. Amazon's two-pizza rule (roughly 6-10 people) keeps teams well within Dunbar's number, where full-mesh communication remains possible and trust doesn't require formal mechanisms.