I don't really blame humans in particular, a bear can eat it's prey alive and feel nothing at all about it, and many other similar examples of cruelty exist in nature, many even eat their own species in special circumstances, despite that I don't consider any of them evil.

Nothing short of a highly contagious virus that affects the brain and makes us more emphatic (with no other side effect) would break the cycle, but that's just sci-fi talk.