Given the scarcity of hard evidence and various conflicting interpretations I suspect it’s going to be difficult to come to firm conclusions on this topic. I would say, though, that it’s very important not to mis-characterize Darwin’s take on evolutionary processes. It’s unfortunate that “survival of the fittest” was such an easy meme; what Darwin (and all subsequent students of evolutionary theory) actually meant was “survival of the best-adapted.”

We see plenty of cooperation among social species like ants and termites and bees. We see brutal inter-group competition (most visibly among males, but also more subtly among females too) in animals like chimps. Birds and many species of insect can be highly territorial. There’s no simple dog-eat-dog rule. It’s all a question of adaptation to circumstances. In the case of our own species we cooperate and we compete. Like all complex ecosystems there’s a mix of behaviors. Often, because we’d like to have a simple rule or a single way of viewing things, we over-simplify. But that’s generally the road to missing something important later on.
