Saved by Ian Vanagas and
The Dunbar Number as a Limit to Group Sizes
Dunbar actually doesn’t say that we devote “grooming time” to the whole social group of 150. Rather he says that the 150 is made up from welding together much smaller “primary networks”: coalitions, friendship groups. Intensive grooming (language, for humans) is reserved for close friends. Our intimate group is very small, averaging just five.
Matt Webb • Dunbar’s number and how speaking is 2.8x better than picking fleas
There is, they suggested, a limit on the number of people we can feel sympathy for, and this seems to set a limit on other groupings where close psychological interaction is required.