1. 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.

2. 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 ( ) depending on the country. Why?
Infant mortality rates: number of infant deaths per 1,000 live births

3. Population Profiles
-bar graph showing the number or proportion of people at each age for a given population.

4. 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
male: left-hand female: right-hand
vertical axis: age in 5-year or 10-year intervals

6. China Population Pyramid in 2005

7. Population Pyramids and Demographic Stages
characteristics shapes of ‘pyramids’
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

9. 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

10. 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 years after reaching replacement fertitlity

11. 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

12. Phase 4 (postindustrial stage)
Phase 4: low birth rates, low death rates, low growth rates
United States, Canada
Better education, more affluent, cultural attitude toward smaller families, better standard of living

13. Overview of pyramids

14. 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
Western Europe, Japan, Italy, Spain

15. Comparing 3 different growth pyramids