Issue #24 - Dunbar's Number 🕸️

Mental Models Weekly is back with Dunbar’s Number - a useful mental model from the social sciences that is widely visible!

Anthropologist Robin Dunbar brought us Dunbar’s Number, and it refers to the number 150. 150 is a rough cognitive limit for the number of acquaintances with whom we can comfortably maintain social relationships. To put it more simply - Dunbar said:

Dunbar’s numbers is often thought of as just one number, but it’s actually a hierarchy of numbers (full study details here).

Here’s the hierarchy:

Dunbar found that our brains can generally manage keeping track of about 150 casual acquaintances. When the group size increases beyond 150, people tend to feel disconnected. Dunbar noted in his research that 150 is the size of many human groups - such as hunter gatherer communities as well as military groups.

Your 150 could include friends, colleagues, and family members.

The next group down is to people we’d call friends and often extended family, maybe people we see more regularly. This is said to be 30-45 or sometimes as high as 50.

The next group down is the people who you might say you’re close to, they might be family or good friends, and it’s suggested this is around 9-15 people.

Finally the intimate group. This is “the set of individuals from whom the respondent would seek personal advice or help in times of severe emotional and financial distress”. These are your best friends and/or immediate family members.

Can you relate to any of the group sizes? I can see how they are true in my life. It’s well worth keeping Dunbar’s number/s in mind designing groups in professional organizations as well as personal ones so they can function best!

📖 Robin Dunbar was a prolific writers, check out his works here

📄 Here’s one of the key studies if you want to dive into the science

🔖 If you’re thinking “Wait, I’ve got waaay more than 150 FB/Twitter etc friends!” Here’s am article addressing just that.

Reply email 📧 or tweet me 🐦 @juliaclavien!