The historians, economists, sociologists, and specially demographers are interested in "demographic transition".
Its essential problem is the evolution of fertility and mortality, and during the course of time, the result of this evolution is that the population of each society changes from the biological equilibrium to the socio - economic one.
In this stage, the population growth is finally the function of rationalization of the behaviors; but it is necessary to add that the migrations have also an important role.
It is true to say that the combination of these factors, such as
economic, social, cultural and historical ones have the most influences in this process.
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