Demographic Transition Model

Demographic transition (DT) refers to the transition from high birth and death rates to lower birth and death rates as a country or region develops from a pre-industrial to an industrialized economic system. The theory was proposed in 1929 by the American demographer Warren Thompson, who observed changes, or transitions, in birth and death rates in industrialized societies over the previous 200 years. Most developed countries have completed the demographic transition and have low birth rates; most developing countries are in the process of this transition. The major (relative) exceptions are some poor countries, mainly in sub-Saharan Africa and some Middle Eastern countries, which are poor or affected by government policy or civil strife, notably, Pakistan, Palestinian territories, Yemen, and Afghanistan.

The demographic transition model, in isolation, can be taken to predict that birth rates will continue to go down as societies grow increasingly wealthy; however, recent data contradicts this, suggesting that beyond a certain level of development birth rates increase again. In addition, in the very long term, the demographic transition should be reversed via evolutionary pressure for higher fertility and higher mortality.

The existence of some kind of demographic transition is widely accepted in the social sciences because of the well-established historical correlation linking dropping fertility to social and economic development. Scholars debate whether industrialization and higher incomes lead to lower population, or whether lower populations lead to industrialization and higher incomes. Scholars also debate to what extent various proposed and sometimes inter-related factors such as higher per-capita income, higher female income, lower mortality, old-age security, and rise of demand for human capital are involved.

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