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 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’ 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 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 Western Europe, Japan, Italy, Spain

Comparing 3 different growth pyramids