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Studying Human Populations Section 9.1. Objectives: Define four properties used by scientists to predict population sizes. Make predictions about population trends based on age structure. Describe the four stages of the demographic transition. Chapter 9. World Population Over Time.
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Studying Human PopulationsSection 9.1 Objectives: Define four properties used by scientists to predict population sizes. Make predictions about population trends based on age structure. Describe the four stages of the demographic transition.
Chapter 9 World Population Over Time Hypothesize WHY the population has recently grown so rapidly.
Demography • “demos” means “people” • Definition: the study of populations
Forecasting Population Size • Why would it be important to accurately predict human population changes? • Predictions are based on: • Age structure: the distribution of ages in a specific population at a certain time • Survivorship: the % of members of a group that are likely to survive to any given age • Fertility rates: the number of babies born each year per 1000 women in a population • Migration: the movement of individuals between areas
Age Structure Diagrams (p.220) Rapid growth would occur in __________ countries. How would a graph for a zero-growth population differ from a graph for a declining-growth population?
Survivorship Curves (p.220) • To predict survivorship, a demographer studies a group of people born at the same time and notes when each member of the group dies.
Fertility Rates (p.221) • What do you think “replacement level” means? • Why is replacement level more than 2?
Migration • Immigration – movement into an area • Emigration – movement out of an area
Declining Death Rates • In the last 200 years, death rates have declined more rapidly than birth rates. • WHY? • Life expectancy: • Definition: the average number of years a person is likely to live • Higher (longer) in developed countries
The Demographic Transition • Definition: the general pattern of demographic change from high birth and death rates to low birth and death rates, as observed in the history of more-developed countries
Stages of Demographic Transition • Preindustrial condition • High birth and death rates • Population size stable • Transitional - population explosion! • Death rates decline (better hygiene, nutrition, and education) • Birth rates remain high • Industrial • Growth slows • Birth rate decreases • Postindustrial • Population declines • Birth rate drops below replacement level
Assignment #49 • Duplicate Figure 4 (p.221) on graph paper. Label each of the different stages of demographic transition. • Which age structure diagram (Figure 2, p.220) corresponds to each of the transition stages on your graph? • What do YOU think will happen in the next phase of our country’s population growth rate? Explain your reasoning.