Werewolf/Talk

Does anyone know if any work has attempted to address why the werewolf is so vicious? Is it because of the pain of transformation, or the hunger (burns a lot of calories, maybe?) or both? Or is that just too ridiculous a question for most people to tackle? :-)

More relevant questions: if you become a werewolf by being bitten by a werewolf, what made the first one?

Why can werewolves only be killed with a silver bullet? How did people kill them in the centuries before guns? Silver arrows? And why silver?

Have any authors attempted to address these questions? Any folktales about them?