The demographic transition model portrays how a country moves from high birth and death rates to low birth and death rates as it becomes increasingly industrialized.
It describes the changes in a population (age structure, fertility rate, etc.) brought about by technology, education, and economic development. This demographic transition is accompanied by changes in other variables such as urbanization, life expectancy, etc.
Summary of the Stages
- Stage 1 (High Fluctuating): The first stage consists of high birth and death rates. At this stage, the population is stable or grows quite slowly because the number of births and deaths are almost equal.
- Stage 2 (Early Expanding): In the second stage, there is a sharp decline in death rates, causing the population to grow rapidly.
- Stage 3 (Late Expanding): The third stage sees the birth rate fall, which slows down population growth.
- Stage 4 (Low Fluctuating): In the fourth stage, both the birth and death rates are low, resulting in a falling and then stable population.
- Stage 5 (Declining): The fifth and final stage shows little population change, although it is somewhat ambiguous.
Demographic Transition Model Definition and Explanation
Paul Davis defined demographic transition as:
“the transformation of a society from high fertility and mortality rates to low fertility and mortality rates as part of the economic and social development process.” (1965)
The original model, consisting of four stages, was created by Warren Thompson in 1929 and was later developed by other demographers to include a fifth stage.
It portrays how societies change (in terms of population growth & fertility rates) as they become increasingly industrialized & urbanized.
The demographic transition model is not always precise for all countries, but some kind of demographic transition is widely accepted in social sciences. This is because there is a well-established correlation between socioeconomic development and dropping fertility.
Demographic Transition Model States
Stage 1: High Fluctuating
In this pre-industrial stage, birth and death rates are high; because the number of births and deaths are roughly equal, the population is stable.
Birth rates were quite high due to several reasons. There was no family planning or use of contraception. The children were an essential part of the household (carrying water, helping in the fields, etc.), and raising them did not cost much money as there was no education expense.
So, having more contributing hands in the family made sense.
Death rates were high due to famines and high levels of diseases. There was also a lack of healthcare and sanitation.
A high death rate feeds back to the birth rate—if the possibility of death is greater, people want more children to increase the chances of their survival.
At this stage, the population is essentially determined by the food supply—any changes in the latter directly translate into changes in the former.
So, if there is a drought or pest invasion, both the food supply and the population will decrease; if there is any improvement in food production (newer sources or better yield), both will increase.
Until the 18th century, all human populations were at this stage.
Stage 2: Early Expanding
In stage 2, there is a sharp decline in the death rate, causing rapid population growth.
Death rate declines mainly because of changes in food supply and healthcare.
Selective breeding, crop rotation, and other farming techniques increase the food supply. Healthcare also improves through better food handling, water supply, and personal hygiene.
Because there is a sharp decline in the death rate with no change in the birth rate, there is rapid population growth. Moreover, there is also a change in the population structure. In Stage 1, most deaths occur in the first few years of life.
When the death rate declines in Stage 2, it means the increasing survival of children.
So, the population becomes more youthful, and the bottom of the age pyramid widens because of the large number of infants, children, and teenagers.
These young people then start to have families of their own, further increasing the population.
In Europe, Stage 2 began in the late 18th century with the Agriculture Revolution.
For developing countries, the decline in death rates started in the 20th century, and countries like Yemen, Afghanistan, and much of Sub-Saharan Africa are currently at this stage.
Stage 3: Late Expanding
Stage 3 sees the birth rate declining as better socioeconomic factors make people have fewer children, slowing down population growth.
After the decline of death rates in Stage 2, there is a subsequent fall in birth rates in Stage 3. This happens because of improved economic conditions, better access to contraceptives, and women getting education/work opportunities.
Once the death rate starts to decline, parents slowly realize that they don’t need to have as many children to help them in the family business or support them in old age.
Societies at this stage prohibit children from working outside the household and introduce compulsory education.
Both these drastically increase the cost of raising children, making people reassess their ability to have them.
Plus, the fertility rate also decreases because women begin to get educated and join the workforce (Haviland, 2018). They now have less time to raise children, and society starts to move away from the patriarchal view that women are meant only for childbearing.
Examples of countries in this stage include Malaysia, Mexico, Saudi Arabia, etc. All of these experienced a fertility decline of over 50% from their previous stage.
Stage 4: Low Fluctuating
In stage 4, both birth and death rates are low, causing the population to stabilize.
There is a low birth rate because people are now more thoughtful about having children, women have greater opportunities to be independent, and there are easily accessible contraceptives.
In general, as Bongaarts writes, “countries with higher levels of human development tend to have lower fertility rates” (2020).
Death rates are also low due to improved standards of living, advanced healthcare, and sufficient food supply.
So, the birth and death rates are both low and roughly equal, resulting in little or no population growth.
In 2015, the countries that were at this stage included Bangladesh, Argentina, India, etc. In all of them, the total fertility rate (average number of children born to a woman in her lifetime) ranges between 2.0-2.5, which is just above the replacement level.
Stage 5: Declining
Stage 5 sees fertility falling below the replacement level, which causes a declining population.
As said earlier, the original demographic transition model consisted of 4 stages.
Now scholars have proposed a fifth stage, stating that the fertility rate further decreases at this point. However, some argue that it increases.
Replacement level is the fertility level at which a population exactly replaces itself.
Replacement fertility is generally slightly higher than 2.0: two children replace the two parents, creating an equilibrium. What happens in Stage 5 is that the fertility rate falls below this replacement level.
In other words, the birth rate falls to such a point that the population starts to decline. This is currently happening in countries like Japan, Italy, and Germany.
Wealthier people having lesser children is strange from the point of view of evolutionary biology.
It is assumed that natural selection favors people who can use greater resources to create plenty of offspring. Perhaps, this indicates our departure from evolutionary adaptedness.
However, this fifth stage is still somewhat ambiguous.
While most models suggest that the birth rates will stabilize at low levels, others argue that they may rise again. Many of them point toward religious cultures that have high birth rates irrespective of income (Kolk, 2014)
The demographic transition model portrays the changes a population goes through as it becomes increasingly industrialized.
It begins with the pre-industrial stage when both birth and death rates are high (for more on pre-industral societies, see our article on types of societies).
With some improvements in technology, the death rate falls, moving us to Stage 2. Then with greater education, especially for women, the birth rate also falls in Stage 3.
In Stage 4, both the birth and death rates are low, causing the population to stabilize. Lastly, there is Stage 5, where some suggest birth rates fall further to cause a declining population, while others argue for the opposite.
The demographic transition model is not precise for all countries.
For example, many countries like China & Brazil have gone through the stages very quickly due to fast socioeconomic change; others, such as African nations, are still stuck in Stage 2.
Still, some degree of demographic transition is widely accepted in social sciences. The model explains why populations in countries decline, rise, or remain stable.
It also helps us predict population trends, which are crucial for policy decisions.
Bongaarts, J., Casterline, J., & Sweet, J. (2020). “The Future of Family Planning”. Demography. Duke University Press.
Davis, K. (1965). “The Theory of Change and Response in Modern Demographic History”. Population Index.
Haviland, A., Prskawetz, A., & Sanderson, W. (2018). “The Impact of Female Education and Labor Force Participation on Fertility: A Review of the Evidence”. Journal of Population Economics. Springer Science+Business Media.
Kolk, M.; Cownden, D.; Enquist, M. (29 January 2014). “Correlations in fertility across generations: can low fertility persist?”. Proceedings of the Royal Society B: Biological Sciences. Royal Society Publishing.