El Cid:

Although it would be pretty cool to have interaction between the player and ambient life, it would be really really cool if you occasionally saw them hunting each other and interacting in a 'natural' way. ie Herd walking about, predators following at a distance then a chase and a kill.

Agreed.  It would be pretty nice to see those sorts of things.  You may even be able to start your own discovery channel show.....