Transcript The Demographic Transition Model

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
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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
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There was a lack of knowledge of disease
prevention and cure, and food shortages
Stage One Continued
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Raising a child cost little more than feeding
him
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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
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This change began with the 1st 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
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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
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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
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Explanations for the declining birthrate are
somewhat speculative
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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
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Education and living expenses increase for children, and
they are no longer able to provide labor
Stage Three Continued
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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
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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
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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
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This last stage is somewhat controversial, as
not all geographers agree that there is a
stage five
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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
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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
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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
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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
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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
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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
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Return of Stage I diseases (Malaria, SARS,
TB, AIDS)
Caused by:
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Travel
Poverty
Evolution of microbes
The Demographic and
Epidemiological Transition Models