Easily demonstrated by many measures: Basics: they poop and don’t need anyone to clean them. They don’t scream when a predator is around because they understand what can happen. They run from predators.
Simple: they can walk and run and find food for themselves at some point to become self sufficient.
Complex: they know who momma is and live in social groups for the most part. They communicate with each other.
Human babies never do any of this, and that has all sorts of ramifications that can be interpreted as funny, sad, or even cruel.
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we never eat babies…ha ha ha! Just pulling your leg. We don’t.
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we never jail babies…ha ha ha! Oh shoot.
Don’t go imagining things, it could hurt. Just think about these things while eating your delicious hamburger. Your burger meat was once smarter than a baby and had as much feelings as a baby does and more including memories. And they were jailed their entire life and were brutally murdered and pushed thru a grinder until they were just pieces of meat.


If we had to explain to a super intelligent and powerful alien why it shouldn’t eat us but eating our animals is okay we’d have a big problem.
I believe for us the “non human” aspect is most important for us and which animals are food and which are pets is a cultural thing. Because any other property besides “non human” would eg allow us to eat dumb or disabled humans or to breed special food races of humans.
We’re gonna have to beg.