What made the difference between languages? What made the Italian people speaks Italian langauage and residents who lives in England speak English ?!!
In the beginning of life of human, We had become just an one nation and had spoken one langauge. What made everyone in the world speaks his own lanaguage?
The question simply, What made one langauge became a lot of spoken langauge in our entire world?
No one really knows if all modern human languages are descended from a single common ancestor or not. It's possible, but it may be that there is more than one ancestral language, it's difficult to know until the relationships between all the world's languages have been established.
So far the 7000 or so languages currently spoken are divided into about 150 families of demonstrably related languages, plus another 100 or so languages which have no known relationships with any other language. There are some theories linking various language families together, but they are not widely accepted.
Anyway, getting back to your question, all languages naturally change over time. If you were to read the earliest written Arabic texts, for example, you would find that the language used is not the same as how people speak in modern Egypt (and there is even a difference between how you speak and how your grandparents speak). Now, multiply this change over hundreds of generations and the difference will be very great indeed. In each speech community the language will change in different ways; and if there is little contact between communities, the way two communities speak will begin to differ, until eventually they will be unintelligible to each other. This has been documented in recorded history: the Roman Empire spread the Latin language over much of Europe, over time the language changed in different places, becoming Portuguese, Galician, Spanish, Catalan, Occitan, French, Italian...
The longer two dialects/languages are separated from each other, the greater the difference will become. Most linguists consider that after about 10,000 years of separation, the difference between two langauges will be so great that their relationship will be impossible to ascertain. For this reason, we will probably never know how many languages really were spoken in the beginning.
Well actually the theory which has more support among the scientists says that the language as a complex system, did not appear in only one social group, on the contrary. One theory says that the language was developed with the hommo sapiens when the men was able to develop an "abstract thinking" and talk about concepts.
I believe that there is only one langauge which is divided into a lot of language in the present.
Naturally, in the existance of human on earth, he had lived in one place ,one nation and one community and speaks one language normally. But when the human is reproducing and is spreading around the world, some humans may be separated from others by several ways - may be geographic boundary , their behaviors, the power of set or group on others in the same nation-. This make every group to create a new language that may be understood amoung every individual member in his nation.
Where do you read that in the beginning existed only one language?
Here's an extremely detailed diagram of the Indo-European language tree you might find interesting: