Exciting new scholarship is exploding many of the old “myths” about animal sacrifice and casting fresh light onto the origins and meanings of this ancient and—to many of us today—mysterious practice.
Some findings from the emerging new consensus on the topic:
Animal sacrifice is a phenomenon of pastoral and agricultural societies. Hunters-gatherers don't practice animal sacrifice. (Think about it: how could they?) Of course, they do make offerings; hunters may set aside the god's portion from their kill. But in virtually all known examples, animal sacrifice comprises the offering and sharing of a domestic animal.
Animal sacrifice is not a “primitive” phenomenon. The old “evolutionary” paradigms for understanding the history of religions broke down long ago. Some religions sacrifice; some don't. The absence of animal sacrifice in contemporary Judaism and Christianity is due to specific developments in the history of these particular religions, which cannot properly be generalized to other religions.
There is no single reason for, or meaning of, animal sacrifice. Animal sacrifice is polysemous: it means different things to different people. It may mean something different to every single person attending any given sacrifice. Previous theorists attempting to extract a single origin, purpose, or meaning for animal sacrifice were mistaken. While it makes sense to compare sacrificial practice across cultures, there are no universals when it comes to meaning.