why do animals have to eat meat??

Hey Andreas,
I've just been thinking about the nature of living things lately, and it kind of baffles me. I fully adopt the idea that man should be vegan and consume no animal protein, for it is already used and useless to the body. But, on the other hand, why do animals feel such an instinct to eat meat. Even chimps who are closely related to our genetic structure eat meat. It just seems to me the world would be a better place if there was no violence, even from animal to animal. Why is it that "animal/primal nature" prevents this from occurring? For instance, my cat, whom I love like a child, is the most kind, loving creature- but I brought home a fish a while ago and my cat would stop at nothing to get to the fish, and eventually ended up eating it. This kind of behavior just doesn't make sense to me. Thanks Andreas,
Jackie Tweet