Groups and Sub-Groups

I just read the article on Dunbar's Number. While the general concept makes sense, I don't know about 150 being the magic number.  I think it would depend on the purpose for which the group is gathered.  Maybe 150 people could live in the same cave, assuming the cave was large enough, but they would probably hunt in smaller sub-groups so as not to spook the game.  The exception would be a big drive hunt where they were trying to get a bunch of buffalos to jump off a cliff, which is the way Native Americans used to hunt buffalo before they got horses.  Such a drive hunt would require extensive planning and organizational structure, otherwise the buffalos might end up driving the hunters off the cliff instead of the other way around.

Last I heard, 150 would be about the size of an infantry company at full strength, but that company would be divided into four platoons, each platoon would be divided into four squads, and each rifle squad would be divided into two fire teams.  Actually, one out of the four platoons would be a weapons platoon and one of the four squads would be a weapons squad, which would be divided differently than the rifle platoons and squads, but we don't need to get into that here.  The point is that groups are divided into sub-groups that can operate more or less autonomously or combine with the other sub-groups, depending on the mission or task at hand.

Social groups are like that too.  We all have our little circle off friends, but that circle might be part of a larger circle of people who we might also count as friends, but not necessarily as best friends.  Most social groups have some kind of leadership.  In an organized club it might be the officers or directors, in an informal social circle it might be a few "cool kids" who the others look up to as role models.

Another consideration is how close people live or work to other people in the group.  Rural communities might be bonded to each other just as strongly as city dwellers, but they don't need as many rules because they are not always getting into each others faces.  A barking dog in the next apartment would certainly be more annoying than a barking dog on the neighbor's farm a quarter mile away.  Studies have been done with various animal species that suggest each species has an optimal population density.  Even if there is plenty of food and water to go around, overcrowded animals tend to squabble more and display other signs of stress.  If population density is too low, some species will quit breeding.  Apparently, a certain amount of competition is good for business.