The Demographic Transition Model

The Demographic Transition Model and Population Pyramids

The Demographic Transition Model is a visual representation depicting population changes over time.

The model is broken into four different stages with a recently added fifth stage to account for declining populations in MEDCs.

Stage One

The first stage, seen in pre-industrial/traditional societies,  is characterized by high death rates and birth rates which result in fluctuations in population and an overall slow growth rate.  The high death rates are a result of a lack of sanitation, medical care, famine, drought… The high birth rates are can be accounted for by traditional cultures where a large family is valued, a lack of family planning,   and the need for children to help financially support the family.

The change in population has a strong positive correlation with the food supply. As the the supply of food increases so does the population, but when there is a shortage or decrease in the food supply,the population will decline.  In this stage, Malthusian theory is observable.

While no country today is considered to be in stage one, there are a few remote, traditional societies  who reflect trends in stage one.

Stage Two

This stage is marked by a sharp decrease in death rates due to improvements in food production (a stable food supply) and sanitation (water improvements, sewage, food storage). This can clearly be seen in a decrease in the infant mortality rate and an overall increase in life expectancy.

These improvements in health, sanitation, and overall life expectancy result in a high growth rate as the gap between birth rates and death rates increases. 

Stage Three

The third stage is reached when birth rates begin to fall. As health improves and the infant mortality rate is decreased, parents no longer need to have large numbers of children to ensure that they are taken care of when they become elderly.  The rural to urban migration also contributes to lowered birth rates, as the traditional cultural norms of having large numbers of children are diluted by city life. Women in wage earning jobs must juggle work and raising children, and costs of mandatory education ameliorate the idea of children being economically beneficial to families.

Stage Four

A country has reached stage four when there are low birth rates and death rates; however, death rates may rise slightly as a result of an aging population which is reaching the end of their life span. The growth rate becomes steady.

During stage four, fertility rates may fall below replacement level (< 2.1).

Stage Five

Stage five has been added by some demographers to illustrate changes in  population seen in MEDCs which have below replacement level  fertility rates (<2.1).   Most European countries have death rates which are above birth rates and are considered to be in stage five.

 

 

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