I didn't do any history research on the subject but my own conspiracy theory suggests that the whole "humans have soul, animals don't" thing was invented to justify the natural world destruction.
Human-centric worldview and “only humans have souls” goes back to the dawn of recorded history. We often lived in closer confines with animals, often sleeping together for warmth, protection and to watch for predators.
However killing animals for food was the way humans stayed alive when food was scarce as we pushed further into habitats that weren’t temperate.
If anything I guess that the “only humans have souls” story arose as a necessary psychological protection mechanism for people who raised and got to know their animals and then had to slaughter and eat them. Same way people also try to dehumanize the enemy in war in order to not be crushed by the knowledge of killing another human being.
Then once we stopped spending so much time with animals it was easy to continue the narrative since we don’t spend time observing them close up anymore and getting to know them personally.
People don't have to dehumanise animals to slaughter them.
American Indians thanked the spirit of the animal that just killed. Kobe husbandsmen massage, wine and dine their prized cattle. A guy in a Reader's Digest joke was surprised his daughter was delighted the cow with big blue eyes she fed through the fence ended up on her plate.
Greek-Roman traditions allowed a soul to animals. Humans have a God-given part that allow them to determine right and wrong for themselves. This passage by Marcus Aurelius, Roman emperor upto 180 AD and Stoic philosopher assumes it.
> The mind is the ruler of the soul. It should remainunstirred by agitations of the flesh—gentle and violent onesalike. Not mingling with them, but fencing itself off and keeping those feelings in their place. When they make theirway into your thoughts, through the sympathetic link betweenmind and body, don’t try to resist the sensation. Thesensation is natural. But don’t let the mind start in withjudgments, calling it “good” or “bad.”
