Dunbar’s other numbers

You may have heard of Dunbar’s number. British anthropologist Robin Dunbar said that humans can keep up with about 150 stable, casual relationships.

He said that’s “the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar.”

Today I learned that Dunbar has a bunch of other numbers too:

• 1500: The max number of people we can name and recognize
• 500: The amount of acquaintances we can keep
• 150: Our stable relationships (this is one commonly called “Dunbar’s number”)
• 50: People we call friends, or would invite to a group dinner
• 15: The close friends we trust and confide in
• 5: Our best friends and closest support group

If you look closely, there’s a divide-by-three-ish thing going on there.