tHE THEORY OF dEMOGRAPHIC tRANSITION
The Demographic Transition Model/Theory is one in which there are four stages based on how nations reach industrialization. According to demographic transition theory, societies transition from high birth and high death rates to low birth and low death rates.
A scholar by the name of Thomas Malthus once said that population growth is limited by available resources. But if that statement is true, why is the world's population growing so rapidly in the parts of the world that have the fewest resources? This can be explained with the Demographic Transition Model/Theory.
The transition from high birth and death rates to low birth and death rates that happen due to economic development can be broken down into four stages.
Stage One: The Pre-Transition Stage
During the pre-transition stage, societies have both high birth and death rates. Because both rates are high, the population tends to grow slowly and also tends to be a population of youth where many people are born, but few live for long periods of time. No longer is any country in the world still at the pre-transition stage.
In pre-transitional society, the youth are considered as an economic benefit to families as they reinforce the high birth rates. Child contributions to the household economy included things such as caring for their younger siblings, cleaning, cooking, working in fields, etc. Raising children had cost little because of the lack of educational opportunities. And as these children grew older, they became the primary source of income and insurance for adults who were reaching older ages.
Stage Two: The Early Transition
In stage two, countries are beginning to industrialize, and a dramatic drop occurs in death rate. This rapid decline in the death rate is initially due to two factors: the improvement of food production and the improvement of health and sanitation. More efficient agricultural practices improved the food production industry and there was more transportation available for the distribution of foods and other goods. This prevented death that was caused by starvation and/or lack of drinking water. As for health, it was improved through medical progress along with more advanced sanitation methods coming from water supply, handling of foods, sewage and of course, general and personal hygiene.
As the death rates are falling, the birth rates are staying high. This results in what is called a population explosion. This growth in population is not due to increasing fertility, but to the dramatic decrease in deaths. There are many people being born and now more of them are able to live longer. The drop in death rates also changed the age structure of the total population in a society. Mortality in stage one of the transition model/theory was especially high among youth and children between the ages of 5 to 10 years. The decline in death rates in this second stage is able to improve the survival for children. Therefore, the age structure of the population became increasingly youthful.
Stage Three: Late Transition
During the Late Transition stage, birth rates are falling, which eventually balances the lower death rates. Falling birth rates overlap with many social and economic changes. Some of these factors include better access to contraception, women becoming more equal in social status amongst men, commercialization of agriculture, urbanization, reduction of children working, and increase in educational opportunities. The increasing female literacy and employment rate is also what lowers childbearing.
The age structure of population once again, changes as birth rates fall. With families having fewer children to support financially, there comes a decrease in the population of youth as well as the dependency of the youth. On the other side of things, people are still continuing to have longer lives, which means that the population as a whole is growing older. This thereby creates a higher rate of dependency for the old-age. Because of the decline in youth dependency and the increase in elderly and senior dependency, a window of opportunity is opened that is called a demographic dividend. The population consists of fewer people who are the dependents (the very young and the very old) and there is a higher population of people who are working adults, which yields an increasing economic advancement.
Stage Four: Post-Transition
Post-Transition is the final stage of the Demographic Transitional Model/Theory. During this stage, birth rates begin to fall in line with the death rates which results in the stabilization of the population as a whole. There are and has been cases, however, where the birth rates have dropped even lower than needed, which then results in a shrinking population. In already developed countries, the death rates tend to remain consistently low or even slightly increase because of diseases related to things such as high obesity, not exercising enough, and because of the aging population. As the population growth continuously slows down, the larger generations born during previous stages such as the people born in the "Baby Boom Period" put and increasing economic burden on the younger working population that is smaller in size(amount of people). This may cause for countries to have difficulty for funding pensions and to provide other social services and sense of security for those who have retired.
The image below shows a generalized model of the Demographic Transition Model. Most of Western Europe had gone through the demographic transition in the very past centuries. Before the 1700's and even before the Industrial Revolution, the European population was stable because both birth and death rates were high. The Industrial Revolution in the 1700's and the 1800's caused their population to explode and by the years in the 1900's and the 2000's birth rates dropped to match the low death rates, stabilizing the population and shrinking it slightly, little by little.