Dunbar Layers (5-15-50-150-500-1500)

Robin Dunbar's finding that human social networks organize into nested layers of predictable size, each associated with different levels of emotional closeness and interaction frequency: 5 (intimate support group), 15 (close friends), 50 (good friends), 150 (meaningful relationships—'Dunbar's number'), 500 (acquaintances), 1500 (people you can recognize). Each layer requires roughly 3x more people than the one inside it. These layers are neurologically constrained by neocortex size and represent the maximum number of relationships a human brain can maintain at each depth.

When to use it

When designing team sizes and organizational structures; when personal networking feels broad but shallow; when organizations grow past ~150 and informal coordination starts breaking down; when allocating limited relationship maintenance time across your network.

How it can help

Audit your network against Dunbar layers. Most people over-invest in the 150+ layer (networking, social media connections) and under-invest in the 5-15 layer (deep relationships that provide real support). In organizational design: teams should map to Dunbar layers—working teams of ~5, departments of ~15-50, and organizations that restructure as they cross the ~150 boundary. Companies that grow past 150 without creating sub-structures experience the breakdown of informal coordination that worked when everyone knew everyone.