One of the common factors which seems to go hand in hand with some of the most base acts imaginable is that it most often involves a group of people ganged together in some kind of mob. I'm fairly certain that most of them, on an individual basis, wouldn't commit these kind of acts.
Paris Match (weekly French news magazine, for those in the US who haven't seen it) recently carried before and after photos of a man buried up to waist who was stoned to death by a mob. Many of those throwing the rocks appeared to be little more than children. The man's crime was adultery. It certainly brings home the realisation that civilisation,for many, is only a thin veneer.