Your Brain Has a Friend Limit. You're Probably Ignoring It.
/ 1 min read
You have 847 Instagram followers. Your brain is managing around 150 of them. The rest are just noise it politely tolerates.
Robin Dunbar was studying primate brains in the early 90s when he noticed something odd, bigger the neocortex, bigger the social group. There was clean corelation accross species
Then he plugged humans into the equation. The number that came out: 150. He didn’t stop there. He checked it against history — Roman military units, medieval villages, hunter-gatherer tribes. They all hovered around 150, without anyone planning it that way.
The brain wasn’t following culture. Culture was following the brain.
It’s Not Just One Number
Dunbar found concentric circles:
- 5 — people very close to you (would call at 2am)
- 15 — people you deeply trust
- 50 — people you’d invite to dinner
- 150 — your tribe
Each layer is roughly 3x the last. And it’s zero-sum game (in terms of attention) – someone new comes in, someone else quietly start slipping out.
You already know who matters. The number just confirms it.