The singing gorilla

How animals think and feel is a question which has long occupied scientists. Pavlov's famous experiment apparently proved that dogs negotiate the world purely on instinct because they automatically salivate at the ring of a bell which they associate with being fed. What he failed to note was that exactly the same is true for humans. So where, if anywhere, does the difference lie? Animals are capable of showing fear, then why should they not also be capable of showing love, envy or sadness? If humans are the only mammals capable of creativity and emotion, why do wild gorillas sing when they are content? This text enters the world of animal's minds, showing that the thought process of even relatively simple creatures, such as birds, are far more complex than people thought.