I think the simplest test would be to determine if animals had a sound or body language for that emotion. We can clearly see or hear when most mammals are expe

I think the simplest test would be to determine if animals had a sound or body language for that emotion. We can clearly see or hear when most mammals are experiencing fear, joy, sadness, anger, etc. They might not understand it intellectually, but I think we'd be hard pressed to argue that they don't feel it or understand that their emotion is in response to an event they experienced.