Plato's fifth book of The Republic, over a millennia ago, cast doubt on our ability to trust what appears obvious to us. Philosophy has taught us that there is no absolute reality, not at least one we can either prove or agree on. Psychology has taught us that what we see is heavily influenced by our peers. What the group believes to be true has a very strong influence on how we perceive reality. Today, science, that is testing our assumptions by trying to disprove them with experimentation and carefully examined data, has shown over time that much of what we have presumed about the workings of nature has been incorrect.
Pigs are in fact very intelligent.
What we see as orneriness is probably more a factor of their poor eye-sight, than a lousy disposition. Sharks no more care about preying on humans specifically than they would consider riding a bicycle, because for most of their time on Earth humans did not exist. When we did emerge, some four million years ago, we walked on land, not teetered off surf boards. It's only when humans, kicking and thrashing, act like shark's natural prey do they become shark meat. Night studies on hyenas have proved that they are very aggressive and successful hunters.