Dunbar's number and the modern network: where the cracks show

In the early 1990s, anthropologist Robin Dunbar noticed a correlation between primate neocortex size and the size of stable social groups. Extrapolating to humans, he predicted a typical group ceiling around 150 stable relationships. The number stuck. The nuance didn't.

Dunbar himself describes the structure as nested layers, not a flat number: an inner core of about 5 (deepest), then 15 (close), 50 (good friends), 150 (the number people remember), 500, and 1,500 at the outer edge. Each ring needs roughly one third of the time of the ring inside it.

The average smartphone holds 200-500 contacts. That's 50-300% over the 150 ceiling - and the holder did meet each of those people, did mean to keep in touch with each of them, and is not keeping in touch with most of them. The contradiction is exactly the pain personal CRMs solve.

What the model predicts (and lived experience confirms) is that the rings re-sort themselves quietly: someone falls from "close" to "good friend" to "acquaintance" not because of conflict but because of capacity. The drift is unconscious; you only notice when you bump into them at the supermarket.

A personal CRM doesn't try to push you past 150. It tries to make 150 stay 150. The cadence field is the explicit ring-assignment: weekly = inner 5-15, monthly = the 50, quarterly = the 150, yearly = the 500. "Never" is honest - some contacts genuinely belong on the dialer-only edge of your network, and labelling them so frees you from low-grade guilt.

After about three months of consistent logging + cadence respect, the network feels noticeably different. Specific people you'd lost contact with come back. The supermarket conversation becomes a planned one. Birthdays land on time. The biggest non-obvious effect: the quality of your time with the inner 15 climbs because you arrive remembering specifics.