This bit of sociology was new to me, the Dunbar Number, a proposed measure of the limit to the number of persons with which a person can maintain stable relationships. A number around 150 has been suggested as the mean group size with sufficient reason to remain together. Its been suggested that social networks may also be limited in this way. In part related to some of Gladwell's Tipping Point arguments. Here is a further discussion, with some detailed debate. Not sure if I buy this, but its a intriguing idea.
I think it is too simple to say that the Dunbar Number is "limit to the number of persons with which a person can maintain stable relationships". It is more about group size -- the larger the group, the more "grooming" time is required to maintain unstructured trust (the kind of trust that doesn't require rules).
In my series of articles on the Dunbar Number (of which you linked to the first one) I point out that in fact the limit of 150 is for survival groups who can afford the huge cost of grooming required (over a third of their time), and in fact most social groups max at about 50 (and I have a lot of evidence to back this up in subsequent articles).
However, this limit is only for groups that require unstructured trust -- you can think of it as that sort of unconscious evaluation of someone when you basically know that they are trustworthy. This kind of trust is a very primal thing.
Once you apply some rules and regulations, punishment and reward, you are creating a structure for trust, and thus can support larger groups. But the default for these type of groups is that you start out non trusting, and only gain trust progressively through the structured rules.
Posted by: Christopher Allen | June 11, 2006 at 11:58 AM