I agree completely. For instance orangutans would have a hard time ever developing a generational culture. I was weakly implying emergent social culture with my high density requirment, but probably wasn't explicit enough. My thinking was that with the combination of big brains (intelligent), hands (ability to make complex tools), few offspring (highly nurtured), and high density (implied social beings), methods of hard symbolic recording would emerge. And certainly that is a necessary component to "civilization level intelligence."

I really think a lot has to do with hands and the environment that encourages a progression of tool usage. On land you have clubs, fire, spears, etc. In water, it is hard for me to see a progression of benefiicial tools. About all there is to do, is prod (ability is oft repeated in nature), and build nests (ditto). Also, the 3 dimensional media seems to encourage high numbers of offspring and limited nurturing (main exception being sea mammals which came back from land). It would be interesting to know if Neanderthal could have made the leap to writing or did there need to be another significant mutation for that level of reasoning to develop.

One final point, was the development of clan warfare necessary for the advancement of civilization to develop writing? Clan warfare would tend to encourage specialization of clan components (leader, healer, hunter, etc). The sum of the parts being greater than the whole, was it really clans that evolved rather than individuals? A side effect of clan (small group) evolution might be wise men specialists/priests which would invent hard recording of events.

The game theoretic aspects of cooperation and specialization potentials are well encoded in the DNA from the beginning. Any multicellular organism is an example of these characteristics. So, it is not surprising that it would emerge at the next level up. Current civilization advancements can be looked upon as simply evolution of the group into a more advanced meta-being. Will we create a super intelligent AI that will become our "brain"?