http://www.schneier.com/blog/archives/2009/07/security_group.html
Primatologist Robin Dunbar derived this number by comparing neocortex — the “thinking” part of the mammalian brain — volume with the size of primate social groups. By analyzing data from 38 primate genera and extrapolating to the human neocortex size, he predicted a human “mean group size” of roughly 150.
This number appears regularly in human society; it’s the estimated size of a Neolithic farming village, the size at which Hittite settlements split, and the basic unit in professional armies from Roman times to the present day. Larger group sizes aren’t as stable because their members don’t know each other well enough. Instead of thinking of the members as people, we think of them as groups of people. For such groups to function well, they need externally imposed structure, such as name badges.
I’ve been thinking about the idea of the nuclear family vrs the extended family for awhile now and it was interesting to compare to this break down of human group sizes to family group sizes. The nuclear family (and it’s associate the post modern family) is the current norm due to various societal factors, especially the mobility of today’s workforce.
By reducing the size of family groups a person also has a reduction in size of the groups mentioned in the article. With fewer people available to seek help in times of severe emotional distress and the larger group of people with which you have special ties you put significantly greater strain on the nuclear family. That is likely one factor leading to the greater number of post modern families. It’s also a significant contributor to the additional reliance on government to provide services that would otherwise be provided by an extended family.
