We are at the top of the animal hierarchy and should treat other animals accordingly in order to further our own species.  We have always been superior to animals. Just as a lion can kill antelope and a frog can kill insects, so too human beings have struggled their way to the top of the food chain. Why then can we not exercise the power we have earned? Animals exercise their power and we should do the same. It is our natural obligation to do so.  The reason we have always killed animals is because we need them. We need meat to be healthy and we need to test medicines on animals to protect our own race. We use animals to further our own race. This too is surely a natural obligation.