(This belongs in the context of my parallel reply to Tom; it might make more sense if you read that first.)

My sole quibble would be the size of the tribe. 500 seems way too large; as I understand it, primate tribes have at most a few dozen members.

To get around that limitation, humans have gradually scaled up the concept of hierarchies of individuals to become hierarchies of tribes. The first manifestation (and one seen among other primates) is competition between tribes. The alpha tribe in an area can force the beta tribes to leave.

Fast forward a million years to today and you see an amazingly elaborated global hierarchy of tribes. Neighborhoods, boroughs, cities, counties, states and provinces, regions, nations, blocs of nations, and--a relatively new innovation--organizations at the pinnacle of the hierarchy like the League of Nations and the UN. Much of the conservative resistance to the UN is, I think, an instinctive resistance among alphas of a nation-tribe to becoming betas of a global-tribe. Our collective folk wisdom (verbal expression of our instincts) includes the saying that it's better to be a big fish in a small pond than a small fish in a big pond. It's better to be the alpha of your own tribe than a beta in somebody else's.

Another characteristic of primate tribes we've retained and enlarged is the tribe's suspicion of outsiders. Today we call that patriotism, but it could more accurately be called xenophobia. Another, more subtle, manifestation of that xenophobia is the reaction of conservatives (keepers of the tribe's heritage and identity) to liberals. Liberals show up as virtual outsiders because the questions they ask cut to the heart of the tribe's identity and cohesiveness; liberals don't "fit in". I don't mean this to be provocative, but if you examine conservative rhetoric objectively, you'll see a greater propensity for symbolic violence (akin to the displays of aggression meant to drive off an encroaching primate tribe)--conservatives treat liberals as outside the tribe. For evidence, see 99% of ebnelson's posts.

Note my observation in the reply to Tom about how radical ideologies become conservative when they succeed. Most humans have a capacity for being both liberal and conservative (in the psychological sense) depending on circumstances. Liberal political ideology, for example, is successful locally when it becomes so rooted in somebody's brain that it becomes unthinking dogma. At that point a dogmatic liberal becomes, psychologically, a conservative who defends the liberal tribe's structural integrity, identity, and status quo. "Liberals" aren't immune from displays of symbolic violence against outsiders, because here I'm talking about the deeper instinctive psychological drives that lie beneath the surface political labels "conservative" and "liberal".

(I wrote that paragraph, but even I find it a little confusing. I never claimed that humans are easy to understand!)

I can sort of understand why Fundamentalist Christians are so outraged by the suggestion that we may have anything in common with "monkeys". But if we don't face up to that fact, we can never truly understand ourselves.