The modern concept of the demographic transition explains the process of changing types of reproduction. In addition, it allows you to identify the patterns of this process. The greatest, according to researchers, is the theory of the demographic transition from the traditional to the modern type.
In the whole process, as a result of which the population is stabilized, four phases are determined.
The first phase in the middle of the 20th century went through states with developed industry. This period was distinguished by the fact that the increase in the overall mortality rate (ACS) was higher than the decrease in the overall birth rate (OCD). In a number of countries, the birth rate remains the same, and in some cases even increases.
The second phase is characterized by a continued decrease in the mortality rate. At the end of the period, ACS reaches a minimum. At the same time, the birth rate is also decreasing , moreover, at a faster pace. As a result, there is a slowdown in natural growth.
In the third phase, an increase in the mortality rate is noted. This is due to the active aging of the population. At the same time, the birth rate is also decreasing. Thus, by the end of the phase, OCD reaches the level of normal reproduction.
At the fourth stage, an increase in ACS is noted, approaching OCD or exceeding it in some cases. At this phase, demographic stabilization ends.
A sharp acceleration in population growth began in the 1950s. The onset of acceleration is mainly due to the establishment of an intermediate type of reproduction. Typically, this period is characterized by the fact that a decrease in mortality is ahead of a decrease in fertility. As a result, the increase in numbers is accelerating. This process may not meet the objective requirements of socio-economic development.
At the end of the 18th century, a demographic transition began in some Western European capitalist countries. Subsequently, it spread to other states, and by the middle of the 20th century it covered the entire planet.
The demographic transition has its own characteristics, which are determined in accordance with the course of history. Of no small importance in the process of changing types of reproduction is the cultural, social, political, economic restructuring of society in the process of its industrial development. The demographic transition is also influenced by the form of the socio-economic system in which it occurs in a particular state. According to researchers, in connection with these factors, the power and duration of population growth are also established.
A population transition can take place in one of three typical patterns.
The first was characteristic of the French state. In France, the process of changing types (and modes, respectively) of mortality and fertility was parallel. In this regard, the state practically did not experience a population explosion. However, this scheme is an exception to the rule.
In most European countries, the transition that began in the 19th century proceeded according to a different scheme. According to the scheme, the birth rate lagged from the beginning of mortality by fifty to one hundred years. As a result, at the end of the 19th and beginning of the 20th century, a population explosion occurred in this region.
The third pattern is typical for Latin America, as well as Asia and Africa. In these states, there is a fairly rapid decrease in mortality, and in some of them the indicators are much lower than in fairly developed countries. In these regions, the population explosion was quite powerful. In these areas, natural growth is about 20-35%. At the same time, a massive decrease in the birth rate occurs with a significant delay.