In order to understand the evolution of languages we will start from the “animal language”.
The mimic language of animals (together with the expression of their voice which is a kind of mime of the speech organ) constitutes the only objective base for the study of a comparative psychology.
It is represented by gesture, sounds or noises and physiognomic attitude that are partly imitative (onomatopoeic) and partly instinctive. The latter developed according to the law of heredity and atavism.
It is therefore a non-conventional language understandable to everybody, without any need for instructions or efforts. If animals didn't possess such a language they couldn't merge, make families, build societies, defend themselves from enemies, gather and emigrate in certain periods.
We can assume that mimic language is richer in more intelligent animals. Furthermore, we can observe how different animals use different parts of their body or organs for expressions and mime. In the superior mammals the face, through the mobility of its muscles, is the part of the body that manifests the highest number of expressions.
In many mammals the movements of the ears contribute remarkably to the expression.
Nose, lips and mouth have the most important role in the play of physiognomy.
The movements of tail and feet are very important for the mime and the whole of the body with its attitude takes part to the expression.
The main means for the animal to express feelings, needs and the most intense and violent passion, is the voice. It is represented by barely articulated sounds and noises, characteristics of the different species. Articulated phonetic language is an exclusive prerogative of man and one of the highest that distinguishes him in the animal kingdom.
Man as well, like animals, expresses his feelings through the language; there isn't a sentence that doesn't express an emotional or affective hue. In human language there are many objective meanings and references and they are the characteristic of the utterance of concepts. The names we give to objects and people are symbols of desires and thoughts.
We can use many symbols to express the same desire and thought: symbols are not characterized by uniformity but by variability.
This idea can be expressed also by saying that language is naturally a metaphor. Instead of describing objects directly, it does it indirectly. How does it describe them? Perhaps through sounds that have a partial identity with the objects they are referred to, that is following an onomatopoeic route?
This doesn't seem sustainable. No matter how hard we try, we can't find a similarity between sounds and objects. Neither can we give too much value to the theories that human language originated from purely emotional sounds, exclamations that expressed human feelings. Indeed, between emotional language (used by animals as well) and enunciating language (exclusive to man) there is a fundamental difference and there's no connection between them.
It is certain that one of the characteristics of human language is that it transforms as time goes by; to follow its historical changes, though, is not sufficient to set up a definitive study. Psychology is not enough either to establish the historical principles of language.
Willhelm Von Humboldt followed a new trend on this subject; according to him language is not a simple set of words. Therefore the true divergence between languages is not in the difference in sounds or signs, but in the dissimilar “view of the world”. That is the different mental view of man.
Words and rules of a language are deduced by the development of a coherent speech and can't be considered as separate entities. Basically, language is a continuous process, the renewed effort of the mind to use sounds in order to express its thoughts.
So far we have talked about the language as a physical and phonetic phenomenon; therefore we have described it in terms of physics and physiology. We must now underline that a phoneme is more than a physical unit, a unit of meaning, therefore something immaterial. In other words, in the whole of the acoustic characters of each expression, some elements are used to express differences in the meaning.
Every language chooses its phonemes in a limited number, amongst the huge amount of physical sounds. This choice is not random because every language is built through a precise phonetic scheme.
Nevertheless there are characters which are common to all languages. Let's just think that language, being a symbolic form, has the purpose of bringing men together. This is perhaps the highest aim of all symbolic forms.
Without languages there wouldn't be human communities, but the difference among languages is one of the biggest obstacles to the formation of a universal community of men. The functional unity of all languages consists of accomplishing the same task in the life of all the communities.
Being different, every language has its pros and cons compared to the others. It is not fair to consider some languages more important than others. Linguistic reality can't accept such comparisons.
Psychologists state that without knowing the true nature of languages it is not possible to understand the development of human spirit. The intellectual life of the deaf-mute who can grasp the symbolism of the language takes a completely different form.
We can observe the same change in the life of any normal child once he learns to talk. His mental development is deeply affected by the learning process.
By learning the name of people and objects, he impresses in his memory a long series of words. He also puts words in relationship with meanings of people and objects he knows in practice. In this way he links concepts with their meanings and he develops the process of the objectification of the outside world. Basically, the child takes possession of the meanings of a world unknown to him.
In the same way, learning a foreign language doesn't mean only to learn new words and grammar rules, but being able to think in a different way in the new language. In order to reach this, we must in a way forget our old language and loosen the close bond between words and objects and penetrate the foreign language by interpreting the new spirit. This will allow us to get close to a new world of ideas and meanings.
Of course language not only expresses objects through concrete words, but also through abstract and universal concepts. The first nouns a man uses at the beginning of his life are the concrete ones that will remain fundamental and almost unique in primitive civilizations.
With the improvement of social and cultural conditions, languages have evolved towards universal concepts and categories. As a consequence there has been a wider contemplation of the world. 
