system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do we determine if an animal has feelings, is self aware, or is sentient?

On the topic of animal cruelty... I feel like it isn't bad to eat animals, and birthing an animal just to be eaten may seem harsh, but are the animals even aware of their own existence? 


Edit: Wow! Thanks for all of the responses, I have read many but I'm gonna start reading the rest! I'm starting to feel guilty for my opinion up there, but I know you all just wanted to help!

Edit 2: I came here to see if I should feel bad eating a burger... Now I'm back to the question my sentience phase. Thanks Reddit.

Edit 3: While I would like to get more comments if anyone has anything to say, but I feel as though this has been answered the best it can. I got a little ethics lesson in as well.
gpt
This is an interesting question and there is no single answer. It's not really a question of is an animal "self aware" or "not self aware" and more, "how self aware" is an animal. Even though it is a bit more complicated than this you can think of there being levels of self aware. 

The standard test is called the mirror test.  It's very simple but really clever.  You put a mark on an animal (when it is asleep or not paying attention) in a place that it can't see it, like on it's head. Then you put the animal in front of a mirror.

If the animal sees the mark in the mirror and reaches up and grabs the mark then it recognized that the animal in the mirror was itself. If it doesn't do that then it doesn't realize that the thing in the mirror is itself and then probably doesn't even have an idea of "self". 

You can look up lists of animals that can pass the mirror test.  Great apes can definitely pass it.  Elephants can, probably some types of birds but it is a little less easy to test a bird.  

There are some other tests too, some are "easier to pass" than the mirror test meaning they show a lower level of self aware, and some are more difficult.