The demographic transition represents a theory widely used in demography that allows the understanding of two phenomena: the causes that have caused the increase in world population in the last 200 years and also explains the transformation cycle through which society had to go from be pre-industrial (distinguished by its high death and birth rates) to become an industrial community, distinguished by presenting a decline in both rates.
This theory was raised by the demographer Warren Thompson and analyzes the way in which the death and birth rates come to affect the total population of nations. It is aimed at changes in the causes of mortality, such as diseases that influence specific communities for a long time and explains the changes in their system.
This theoretical model was created, based on the study of the prevailing situation in the populations of North America and the northern part of Europe, beginning with the observation of certain important changes that have arisen in the birth and mortality rates in industrialized communities. By the 1920s, a warning had already been issued about how the industrial revolution had altered different areas of the daily life of communities and generated changes in the economic, social and technological aspects.
However, the environment where this theory was carried out is still in force, since its explanations are still related to many of the situations that countless countries are currently experiencing. For example, most developed countries have already completed this demographic transition, however, those nations that have not yet been able to develop have not yet completed it.
The demographic transition generally goes through several phases:
- Initial phase: in this stage, populations are characterized by high mortality and birth rates. This is the phase where many of the pre-industrial societies remained during the early nineteenth century.
- Second phase: here the birth rates remain high, while the death rate is falling rapidly. At this stage, an improvement in health and nutrition begins to be experienced.
- Third phase: also called the mature industrial phase, it is characterized by the decline in birth rates, while death rates continue to decline. At this stage, the population shows sudden growth and a balance may be observed between the number of deaths and births.
- Fourth phase: in this phase the death and birth rates are extremely high, therefore, they manage to reach equilibrium.
- Fifth phase: in this stage, all those populations where mortality rates exceed birth rates are appreciated.
