I hope this isn't too far a tangent, but from the religious perspective, I've had this theory about animal sacrifice.
I wonder if human beings, as their villages and civilizations developed, saw these animals they were hunting, and later farming (the development of animal husbandry; breeding animals for use or slaughter) as too similar to themselves. The sheep you are eating had human qualities with emotions, fear, affection, etc.
What if the animal sacrifice was a way to deal with the horrors of something that seemed to have emotions, that you had to eat. You spill their life on the ground, give it to your gods, in a ceremony/ritual, as a recognition of how its life must be spilled so your people can live.