you may also know the gorilla Koko, that use sing language. These experiments have demonstrated that these animals are conscious beings, ans have emphaty to some degree.
I got a book out of the library on this when I was about 17. I left it at my friends house who's dad was an elder. The guy pulled my dad into the backroom and produced the book. He told my dad this was a prime example of why he considered me to be bad association for his daughter.