Demographic transitions
• Definition: tendency for a population to shift from high
birth and death rates to low birth and death rates. Often
occurs from economic and social development.
• Countries are usually classified into two groups:
• Developed (US, Japan, France)
• Developing (moderately/less developed): Mexico,
Thailand, Ethiopia
• These categories usually experience similar population
dynamics.
Population Paradox: Key terms
• Total Fertility Rate: Average number of children born to
each woman
• Replacement level fertility: Number of children a couple
must produce in order to “replace” themselves
• RLF ranges (2.1-2.7) depending on the country. Why?
• Infant mortality rates: number of infant deaths per 1,000
live births
Population Profiles
-bar graph showing the number or proportion of people at each
age for a given population.
Age structure
• Population profiles shows the age structure of a
population, which is the distribution of population by age
• These profiles help demographers project how
populations will change over time.
• shows the age and gender composition of a region
• horizontal axis: divides gender and shows absolute
number of people or in percentage of population
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male: left-hand female: right-hand
• vertical axis: age in 5-year or 10-year intervals
China Population Pyramid in 2005
Population Pyramids and
Demographic Stages
• characteristics shapes of ‘pyramids’
o
o
o
o
wide base (true pyramid)
wide middle (bulge), somewhat wider base
urn- or bottle-shaped
reversed pyramid
• Pre-reproductive Age: 0-14
• Reproductive Age: 15-44
• Post-Reproductive Age: 45 and older
Phase 1 (preindustrial stage)
• high birth rates, high (at
time erratic) death rates,
low growth rates
• stage for much of human
history, traditional societies
where people were
susceptible to disease and
family planning was
nonexistent
• practically no country today
Phase 2 (transitional stage)
• high birth rates, declining
death rates, rising growth
rates
• improvements in sanitation
(water) and medicine, lack
of family planning
• in developing countries
such as Iraq, Nepal, etc.
• Population Momentum:
population will continue to
grow for 50-60 years after
reaching replacement
fertitlity
Phase 3 (industrial stage)
• continued decline of death
rates, declining birth rates,
growth rates decline from
high to lower levels
• change in behavior:
adaptation to lower death
rate, in particular infant
mortality rate
• economic change:
urbanization (incentive to
have fewer children/ China),
changes in women’s role,
better healthcare
Phase 4 (postindustrial stage)
• Phase 4: low birth
rates, low death
rates, low growth
rates
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United States,
Canada
• Better education, more
affluent, cultural attitude
toward smaller families,
better standard of living
Overview of pyramids
What happens after Phase 4?
• Phase 5?: low birth rates, rising death rates,
declining growth rates (if birth rates drop
below death rates: negative growth rates)
• Zero population growth: birth rates equal
death rates and there is no growth.
• Graying population: proportion of elderly is
increasing
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Western Europe, Japan, Italy, Spain
Comparing 3 different growth pyramids