Peter Molyneux's favorite word when it comes to describing his games is "simulation." The whole concept behind B.C. as well as the marvelous Project Ego is to create a living, active world that simply reacts to what you do with the main character. In the case of B.C., that living, breathing world is prehistoric and filled with cavemen, dinosaurs and all kinds of smaller critters. It's the ridiculous level of detail that's making us feel like B.C. is going to be such an accomplishment.
The smaller creatures in the lush highlands that serve as the opening area in B.C. includes little vegetable eating dinosaurs, birds and mice. Molyneux mentioned something about functional anthills but we were unable to find any to confirm their existence. The mice, however, were present and would scurry through the tall grasses that also happen to sway in the breeze. The smaller dinosaurs we saw were kangaroo-sized herbivores that spend quite a bit of time freaking out and running away from slightly larger predators. Sometimes you'll see one of those meat-eaters actually catch one of those scampering little veggie-eating dinos. The stampeding dinosaurs and the predators that try to kill them are just one example of how life is and will continue to go on and do its thing in B.C. until and unless you decide to interfere.
B.C. is still early in its development process but it stands to reason that however effective you've been as a leader for your tribe determines how quickly and how intelligently they approach the tasks you set before them. In the above example, wouldn't it be possible for the three cavepeople to learn how to cook while gathered around the campfire? These are the interesting and invigorating questions that Intrepid is dealing with right now in finalizing the depth of B.C.