Animals are pure. No superficial or sick layers.
Humans are animals. Don't even tell me that some of the
behavior that you see in chimps, for example, isn't damned
close to the kind of evil you see in human society.
You can say, "oh, it's all instinct" or something, but what
we learn isn't so different. And dogs (for example) certainly
have learned behavior - which can sometimes be very wrong.