Proof #1 Your lack of proof is my proof. Ever heard of a cat having goals in life? No, because they cannot plan ahead and simulate scenarios. All current psychological and biological understanding suggests so.
Proof #2 Computers with AI set about to mimic human behaviour as closely as possible. In 25 years time it will be possible to create a robot exactly the same as humans, feelings and all. Thus technically not having a "soul" but still being alive.