Demographic Transition 2.5 2.0 1.5 1.0 0.5 0.0 19501960197019801990200020102020203020402050 0 2 4 6 8 10 Growth rate (percent) Population in billions Year Less developed countries More developed countries
Why has the world’s population grown at such different rates throughout history? Natural increase = births – deaths Net migration = immigrants – emigrants Births Deaths Migration
What affects birth rates? Fertility Rates Replacement level fertility = # of children a couple needs to produce to replace themselves Total fertility rate = estimate of the average # of children a woman will produce during her childbearing years (15-49)
Births per woman < 2 2-2.9 3-3.9 4-4.9 5+ No Data Fertility Rates
What affects fertility rates? Importance of children to labor force Urbanization Cost of raising and educating children Education and employment options for women Average age of marriage Availability of pension plans Availability of legal abortions Availability of birth control Religious beliefs, traditions and culture
What affects death rates? Higher food supplies Better nutrition Improved medical and health technology Improved sanitation Safer water supplies
Indicators of overall health Growth = natural increase – net migration Life expectancy Infant mortality **
Infant deaths per 1,000 live births <10 <10-35 <36-70 <71-100 <100+ Data not available
How can economic development help reduce birth rates? Demographers have developed a hypothesis known as the DEMOGRAPHIC TRANSITION. It states that as countries become industrialized, first death rates go down and then their birth rates decline.
4 stages of Demographic Transition: 1.Pre-industrial: birth rate and death rate are both high = little growth.
2. Transitional: death rate falls due to improved living and birth rates stay high = rapid growth.
3. Industrial: fertility falls and closes gap between birth and death rates = low growth.
Low High Relative population size Birth rate and death rate (number per 1,000 per year) 80 70 60 50 40 30 20 10 0 Stage 1 Preindustrial Stage 2 Transitional Stage 3 Industrial Stage 4 Postindustrial Low growth rate Increasing growth rate Very high growth rate Decreasing growth rate Low growth rate Zero growth rate Negative growth rate Birth rate Total population Death rate Time 4. Post-industrial: birth rate falls below death rate = zero growth.