[mensetmanusman]

Humans sacrificed animals when relations between abstract numbers and reality were discovered:

https://en.m.wikipedia.org/wiki/Pythagoreanism

The practice of wonder surrounding numbers and their role in existence has been practiced by nearly every ancient civilization for many millennia.

Definitely not unique to Christianity. Definitely as natural as religious practice itself.

[seanhunter]

Humans may have done that, but not the Pythagoreans, who were vegetarians. From that wiki page:

> The Pythagoreans also thought that animals were sentient and minimally rational. The arguments advanced by Pythagoreans convinced numerous of their philosopher contemporaries to adopt a vegetarian diet. The Pythagorean sense of kinship with non-humans positioned them as a counterculture in the dominant meat-eating culture.