esr102 home

Demographic Transition


This case study of the demographic transition consists of the following parts:

1. This summary of the classical/text book description of the demographic transition with analysis from a "systems" point of view.

2. A framework for examining how people (individuals and societies) make choices - the "choice" viewer.

3.A link to a paper that presents different factors that contribute to the observed transitions.

4. The application assignment for unit 1 that compares the "systems" to the "choice" views.


Potential steady state between births and deaths The population of a country can be described as a potential steady state between births, deaths, immigration and emigration. In these examples we will be only examining the births and deaths such as shown in Figure 1. The number of births is the birthrate * population. Deaths are calculated similarly. It is obvious from this treatment that if births exceed deaths that the population will increase in size.

Figure 1. A systems model for population size that is determined by births and deaths.


The four phases of the demographic transition Our text, and most other introductory texts, describe the "demographic transition" as having four phases. In phase 1, preindustrial cultures that have both high birth and death rates. During this phase the population size doesn't increase very fast at all. Phase 2 is the also called the "mortality transition". Death rates drop due to improved health of the population, including infants. The end of phase 2 and the beginning of phase 3 have the highest net growth rates (birth - death rates). Phase 3 is also called either the "industrial" stage or the "fertility transition". This phase represents the decrease in births that can be correlated to many factors. The factors that lead to the decrease in fertility are the point of this case study. Phase 4 represents post-industrial stage. Populations in this phase have low net growth rates again, leading to net zero population growth, and in some cases negative net growth rate.

Figure 2. The four stages of the demographic transition. Ignore the letters for now.


Relationship between economic and population growth The nations wealth will increase as the economy grows, Figure 3. If the population size grows faster than the economy, the per capita wealth will decline.


Figure 3. Economic growth, population growth and their relationship in determining per capita wealth. The per capita wealth is the total wealth divided by the population size. The link from wealth_per_capita to birth_rate represents a negative correlation, as wealth per capita decreases the birth rate would go down.


Explanations are correlations not cause Some of the descriptions of the demographic transition, and in particular the decrease in fertility are related to the per capita wealth. The nation's wealth can be invested in infrastructure, increased jobs and education. The decline in fertility rate correlates with per capita wealth. It is important to interpret the model presented in Figure 3 as explaining the relationship between the increase in economic indicators and a decrease in fertility, and not to interpret it as if the wealth per capita per se decreases the fertility.

Suggested reasons (see our text page 270) for the decrease in the fertility in contrives include:

availability of family planning (birth control)

delay first birth until later years

women gain access to education

women gain access to jobs and economic

women gain political rights and higher social status

government incentives for having smaller families (or penalties for larger families)

decreased utility of having many children in a agricultural economy

increased value placed on supporting and educating children so that they can work in the industrial economy


How did the fertility transition take place? Of the four phases, the decrease in the birth rate is the most interesting case for this course. The decrease in mortality can be explained by better health care, immunizations, better water and other social infrastructure that would accompany early industrialization. The decrease in the birth rate, however, represents a mass effect that had to have happened by individuals making the choice to either have more children or not. How did these people make decision? Was it because they didn't need to have large families any more and there was immediate value to having only a few children or was it that they were participating in a longer social change that took longer times for individuals to realize the benefits of a smaller population growth.


In this course, we are interested in this phase of the demographic transition because it may help us understand the conditions and processes that may be necessary for a transition to sustainability. Will the population as a whole understand how sustainability will benefit them eventually and thus make individual choices toward that common goal or will there have to be an immediate benefit for each individual sustainable act?

Please go to part 2 - choice viewer


John Rueter
July 15, 2003