I'm curious about where, how long ago, and why ancient humans got the notion that gods (or eventually, a God) wanted sacrifices, whether they be plants, animals, or human beings. By definition, a god would be all powerful, but why would that god demand the destruction of something precious as appeasement for some anger?

I don't subscribe to the idea that ancient cultures were necessarily "primitive" in an intellectual sense, so I don't see belief that a god wants a sacrifice as a primitive idea. This is supported by the fact that people still believe it today. (!) If your god loves you, why would that god want you to kill something? Your human father wouldn't ask you to kill your puppy to prove your love, right? (Ok, I'm digressing...) This is a complicated question posed in a space the size of a matchbook cover--hehe. Any thoughts on this? Any books that might help me understand this better? Many thanks.