Keep that inner circle tight.

In Dunbar’s research, he mentioned that the 150 people are made up of:

5 intimate friends

15 good friends (including the 5 intimate friends)

50 friends (including the 5 intimate friends and 15 good friends)

150 acquaintances (all-encompassing)

Of these, he says that we spend 60% of our time with our core groups of 50 friends, and 40% with the remaining 90 people. The number can be said to derive from our brain’s ability to maintain memories of 150 people, as well as the time necessary to devote to the group in order to keep relationships going.