I heard recently that when The Wizard of Oz came out, more people would have realized how dangerous it was when Dorothy fell in the pig pen. Today, we watch that movie and think it was just about her losing her balance, and maybe wonder why the farmer who saved her was so visibly upset about it. (I contacted my source and he said it was 'just common knowledge', and that pigs have since been domesticated from the wild boars they were, and that I should google, "pigs aggression".)