The Demographic Transition Model

What is it? The "Demographic Transition" is a model that describes population change over time. It is based on an interpretation begun in 1929 by the American demographer Warren Thompson, of the observed changes, or transitions, in birth and death rates in industrialized societies over the past two hundred years or so.

What does it look like?

Stage One: Preindustrial This stage is associated with pre-modern times It is characterized by a balance between high birth rates and high death rates There is a slow rate of natural increase, due to the high death rate Life expectancy would be short, most of the deaths were of children  There was a lack of knowledge of disease prevention and cure, and food shortages

Stage One Continued Raising a child cost little more than feeding him  there were no education or entertainment expenses  in equatorial Africa, there were no clothing expenses either  As adults, they provide labor, carry on the family name, and provide insurance Modern Examples: There are no modern examples

Graphic Representation

Stage Two: Developing Society This change began with the 1 st Agricultural Revolution Characterized by a rise in population Birth rate remains high, but death rates decrease The rate of natural increase is growing slightly, due to the lowering death rate Life expectancy in children increased, due to improvements in medical care and vaccinations

Stage Two Continued Children are still considered valuable as they still provide labor Increased food production led to a healthier population Children survive childhood, and begin reproducing at a young age, with the same high fertility rate as their parents Modern Examples: Yemen, Afghanistan, and Sub-Saharan Africa

Stage Three: Transitional Society This stage is characterized by a declining birth rate The death rate is also declining The rate of natural increase is increasing, as people are living longer Life expectancy is also high

Stage Three Continued Explanations for the declining birthrate are somewhat speculative  In rural areas, a decline in the child death rate mean that not as many children are needed to provide insurance for old age  Increased urbanization increases the cost of living Education and living expenses increase for children, and they are no longer able to provide labor

Stage Three Continued Speculative explanations: Increased literacy and employment lower the expectation for childbearing as the measure of a woman’s worth Increased access to contraceptives allowed families to make decisions concerning the size of their families Modern Examples: Costa Rica, Mexico, and Turkey

Stage Four: Industrialized Society This stage is characterized by stability. The birth rate is low, and the death rate is low. The fertility rate is below replacement levels There is a low rate of natural increase Life expectancy is extremely high, due to access to medical care

Stage Four Continued The population is high and stable. Most of the females have a high level of education and literacy Children are seen as financial liabilities, not assets Modern Examples: United States, Canada, and Australia

Stage Five: Deindustrialized Society This last stage is somewhat controversial, as not all geographers agree that there is a stage five  This stage is characterized by a move from an industrial society to a service based society (secondary to tertiary sectors) Characterized by an extremely low birth rate, and low death rate Rate of natural increase is negative, and life expectancy is high

Stage Five Continued The population is falling due to fertility decline, emigration and, particularly in Russia, increased male mortality. The death rate is sometimes due to "diseases of wealth", such as obesity or diabetes, leading to a gradual fall in population in addition to above aging. Modern Examples: The United Kingdom, Germany, and Japan

The Epidemiological Transition Model

Stage I: Pestilence and Famine Infectious and parasite diseases were principle causes of death along with accidents and attacks by animals and other humans. Thomas Malthus called these caused of death “natural checks” Most violent Stage I epidemic was the Black Plague(bubonic plague or black death) probably transferred to humans by fleas from infected rats

Stage II: Receding Pandemics Improved sanitation, nutrition, and medicine during the Industrial Revolution reduced the spread of infectious diseases. Death rates did not improve immediately and universally during the early years of the Industrial Revolution. Poor people who crowded into Industrial Cities had high death rates due to Cholera

Stage III: Degenerative Diseases Associated with the chronic diseases of aging Heart disease and cancer Sub-Saharan Africa and South Asia have low incidences of cancer primarily because of low life expectancy.

Stage IV: Delayed Degenerative Life expectancy of older people is extended through medical advances. Cancer medicines, bypass surgery, better diet, reduced use of tobacco, and alcohol However, consumption of non-nutritious food and sedentary behavior have resulted in an increase in obesity in this stage.

Stage V: Return of Infectious Disease Return of Stage I diseases (Malaria, SARS, TB, AIDS) Caused by:  Travel  Poverty  Evolution of microbes

The Demographic and Epidemiological Transition Models