I'm pretty sure dolphins aren't actually quite so pacifistic as I present here in their internecine conflicts over primacy.
Neither, on the other hand, do they partake of the viciousness that pervades many of their land-based counterparts, ourselves definitely included. Some animals will fight literally to the death over who leads the pack, who mates with this or that female, etc. And in some species a new leader will purposefully kill all surviving progeny of his predecessor in an effort to ensure that his genes will dominate the pack's future. The animal kingdom isn't a kindly regime. Little, if any, of this sort of behavior has been observed among dolphins. Leadership, while coveted as it is in any species, doesn't evoke such extremes among them; I've simply carried that concept a bit further than is probably true. As Jason points out, the Rousseauan ideal simply doesn't match the reality of the world in which we live.