Like every other animal, the cat has a system for communicating that is related to brain capacities and needs.
Plants, too, have a means of exchange, through chemical messages. Germs also use these techniques, with an added function related to touch which leads to the recognition of protein shapes. Along with the evolution of the species, communication methods have also improved. The more advanced animals use, essentially face codes, associated to various songs. Every mammal family have their personal exchange system, transmitted partly through genes, partly through parental education during childhood. Cats do not escape this rule.
Human beings, for reasons due to the shape of their throats, have succeed in gradually modifying their speech, from grumbles to the more complex language that is now ours. We are so used to it, that we do not realize what an exceptional aptitude this is. Language and intelligence have evolved together during thousand of years, supporting one another, yet one is unable to specify which one has brought the highgest contribution in their evolution.
Several scientists, like Penny Patterson of California, together with her female gorilla Koko, have demonstrated that it was possible to establish a regular and thorough way of communicating between an ape and a human being. In order to achieve this, you only had to use a tool common to both species, ie the same language as used by deaf and dumb people.
The success of these studies was really spectacular. Nevertheless, their most important outcome remained unknown to most people. Researchers had hoped that the monkeys had initiated a sign language (beleived to be richer than their current facial language) that, in turn, could be taught to their children and friends.
In actual fact, nothing happened. The educated apes that had held discussions with their counterparts had only used traditional facial language.