What are the "population growth models" in geography? Emphasize the characteristics of "transitional"! Urgent!

Geographical "population growth models" include primitive, traditional, (transitional) and modern. The main characteristics of the transitional type: the population growth rate rises linearly, the fastest!

"Population growth model" is an index used to measure the regional population growth, which consists of three data: birth rate, death rate and natural population growth rate, in which the natural population growth rate is obtained by subtracting the birth rate from the death rate. If the birth rate is greater than the death rate, the natural population growth rate is positive, indicating that the population is increasing. If the birth rate is less than the death rate, the natural population growth rate is negative, indicating that the population is decreasing.

The development of human society has probably experienced three different "population growth models" so far. The first population growth mode is "high, high and low" mode, or primitive traditional population growth mode.

This population growth model is characterized by high birth rate, high mortality rate and low natural growth rate, and the corresponding stages of human development are prehistoric primitive society and agricultural society. At this stage, due to the low level of human productivity and medical care, the population is prone to death and the mortality rate is high. Therefore, human beings must maintain a high birth rate to increase the population, but the overall population growth rate is still very slow.

Extended data

The population growth mode is "low, low, low" mode, or modern population growth mode. Low birth rate and low death rate correspond to low natural population growth rate. The population growth in the whole region is slow, and sometimes there will be zero or negative population growth. At this time, the region fell into a "trap" of low birth rate.

Due to the decrease of new population in this area and the aggravation of population aging, there has been a serious phenomenon of "population aging". For example, Japan, Germany, Italy and other countries have fallen into the trap of aging. The terrible thing is that no country can raise the low fertility rate.

The only country that has successfully solved this problem is the United States, which temporarily avoids falling into serious population aging and maintains social vitality through immigration policy.