In discussing Dunbar’s Number and urban tribes, I’m looking for fundamental scales of human organization. Ryley pointed me to two quite similar hierarchies:

The military grouping is often said to be consistent throughout history, although with support units it’s hard to be sure apples are compared to apples. I think the numbers have been tending downward in the last 100 years due to area-effect weapons and mobilization (you can control less troops when they’re moving around really fast and you don’t want to keep them too close together). This guy claims that you need 6 people to maintain sentries, which might have something to do with why teams are almost always deployed at least in pairs (eg: one of my favourite video games, Full Spectrum Warrior).

“Support cliques” and “sympathy groups” are so named by Dunbar because of specific ways of measuring them: your support clique is your first line of support in really tough times and your sympathy group is the people who’d be devastated if you died. This table makes it clear that the phrase “urban tribes” was coined by Ethan Watters without much background reading. Watters is talking about post-kinship, post-economic families and needed a snappy name.

Anthropologists are convinced that these group sizes are based on human cognitive limits. I’m not sure I’m ready to give up my dedication to 8ish as a common human grouping (for example, as the maximum size for an ad-hoc meeting) given that 7±2 is the most famous human cognitive limit.