Sorry, I couldn't resist. Fact is, everything we posit here is based on animals not being able to speak or write or have a social set of "language skills as we understand them. Why is there no question of whether we are making a huge assumption based on our limited capacity to perceive the nature of human behaviour?, our inferences on what their behaviour means could very well be laughable to any number of animals if they knew what we were thinking - they could very well be talking to "god" non-stop for all we know, why do we assume what we perceive of their behaviour is the truth about their behaviour, it is really only based on humanities version of reality isn't it?
Of course neither of them are capable of thinking in those terms at all, but we, as humans, perceive those qualities in them which we know exist in oursleves,
Modern science shows the differnces between human thought, and that of other anils be it in neuroscience or linguistics or biology. Humans are quite capable of both imagining all sorts of things but also of discovering physical truths.
To be honest, in this debate i feel like an evolutionist trying to convince creationists by using science against what they want to believe. While there i stil some debate, it is becoming increasingly clear that huan thought is dependent on language, and that the two are deeply connected and co evolved. Without a similar form of linguistic depth an animal cannot evolve a similar level of cognitive ability. (and humans could not have either)