Often, as an insult, some people describe others as behaving like animals. The truth is that no other animal is capable of behaving nearly as badly as humans do. For instance, when soldiers murder, rape and mutilate unarmed and innocent civilians, they are described as behaving like animals. However, no other animal tortures and kills other animals for the mere malicious pleasure of it. People who steal from others and loot the public coffers are described as behaving like animals. However, only humans do that. Insatiable greed is not the quality of any other animal than humans. Vice and virtue are possibly exclusively human characteristics. Other animals behave naturally, something for which they cannot be blamed, as the phrase "behaving like animals" unjustly seems to imply. The ideas that pigs are dirty and greedy are the result human's confinement of pigs and the projection of our characteristics onto them. Jackals may be unable to constrain themselves if they manage to get into a sheep fold, but it is humans who have confined the the sheep and made them weak and dependent, unable to defend themselves. Chimpanzees are known to murder the individuals of competing bands, but they are not very proficient at it ... and they are, anyway, our closest living relatives.
I'm Alan (an anagram for "animal"), an ethical vegetarian.
Our colour vision can be traced back to our distant relatives, the fruit-eating, tree-dwelling monkeys, who benefited from colour vision when looking for (ripe) fruit.