The ability to use language has long been considered to be a key differentiating characteristic that distinguishes man from animals.

Humans seem to acquire language in a manner different from other types of behavioral learning. We learn our native language without instruction, in fact, we can learn 2-3 languages at that age as easily as one, all this without instruction. All this evidence suggests that we have a language organ in the brain which all other animals do not possess. This organ during human development in the first years of childhood is what gives us the ability to speak.

A simple way to disprove this hypothesis is to demonstrate that other species have the capacity to speak but for some reason simply have not developed speech. studies on chimpanzees, which shares 98.4% of the human genetic code have proven that they cannot speak because, unlike humans, their vocal cords are located higher in their throats and cannot be controlled as well as human vocal cords.

While the term "animal languages" is widely used, most language researchers agree that they are not as complex or expressive as the human language. It seems that there are significant differences separating human language from animal communication even at its most complex. These are properties that exist in the human language and not in most animal language:
1. Animal language is Arbitrary: There is no relationship between a sound or sign and its meaning.
2. Humans have what is called Cultural transmission : Language is passed from one language user to the next, consciously or unconsciously.
3. Humans have discreteness: Language is composed of discrete units that are used in combination to create meaning.
4. Human language uses Displacement: Languages can be used to communicate ideas about things that are not in the immediate vicinity either spatially or temporally.
5. Human language uses Duality: It means two levels at once, a surface level and a semantic (meaningful) level.
6. Humans are Metalinguists: They are able to discuss language itself.

Arbitrariness has been noted in meerkat calls; bee dances show elements of spatial displacement; and cultural transmission has occurred with the offspring of many of the great apes who have been taught sign languages, however, these single features alone do not qualify such instances of communication as being true language.

Speech is one way of communicating with each other, and although dogs and cats may not speak the way humans do, they can certainly communicate within their own species and also learn to communicate with humans and even other species they live with (for instance, pet dogs and cats, who live in the same household with humans).

Other types of communication that animals rely on are:
Vocal sounds (vocalization), The language of smell and body language.

To learn about cat communication you may refer to this web-site:
Cat language