Is it possible to turn into a wolf?

Ok, so I was thinking. I know the legend of turning into a wolf goes way back, but surely, it must have started some when, something must have happened. So surely, there must be a way to change. No, I'm not some ignorant, silly little child that wants to be a wolf like Jacob Black...Although admittedly it does seem kind of cool. Anyway, if anyone has seen anything or has any information, I would appreciate it. No negative comments about getting help please, I'm just interested in the subject :)