Chap. 9: The Human Population Sect Chap. 9: The Human Population Sect. 1: Studying Human Populations Key Vocabulary Demography & Demographers Developed vs. Developing Countries Age Structure & Age-Structure Diagrams Survivorship & Survivorship Curves Fertility Rate & Replacement Level Migration (Immigration vs. Emigration) Life Expectancy & Infant Mortality Demographic Transition (Model with 4 Stages)

Demography Demography is the study of the characteristics of populations, especially human populations. Demographers study… historical size and makeup of the populations of countries properties that affect population growth, such as economics and social structure

Developed vs. Developing Countries Developed countries higher average incomes slower population growth diverse industrial economies stronger social support systems Ex: U.S.A., Canada, Japan Developing countries lower average incomes rapid population growth simple and agriculture-based economics Ex: Afghanistan, Somalia, India

Map: Developed vs. Developing Countries

Map: Developed vs. Developing Countries

Exponential Human Population Growth Exponential growth started in 1800s = Industrial Revolution due mostly to increases in food production and improvements in hygiene Problem: Earth can’t sustain this growth!!!

Age Structure Age structure is the classification of members of a population into groups according to age helps demographers make predictions Countries that have… …high rates of growth: have more young people than older people …have slow growth or no growth: have an even distribution of ages in the population

Age-Structure Diagrams = Population Pyramids …a type of double-sided bar graph % of Population Males vs. Females on opposite sides Shape of graph correlates with rate of population growth: Developing countries = rapid growth = more young than old Developed countries = slow growth = about equal numbers of all age groups

Survivorship Survivorship is the percentage of newborn individuals in a population that can be expected to survive to a given age. Related to life expectancy Survivorship Curves Type I: wealthy developed countries, most people live to old age Type II: similar death rate at all ages Type III: poor developing countries, most people die very young, high infant mortality rate

Historical graph of the U.S. Fertility Rate Fertility rate = the number of births (usually per year) per 1,000 women of childbearing age (usually 15 to 44) Replacement level = the average number of children each pair of parents must have in order to “replace” themselves (usually slightly more than 2) Historical graph of the U.S. Fertility Rate

Historical U.S. population growth due to Immigration and Births Migration in general, is any movement of individuals or populations from one location to another. Immigration = movement into an area Emigration = movement out of an area Historical U.S. population growth due to Immigration and Births

Why is the world’s human population growing so rapidly? …because death rates have declined more rapidly than birth rates …because more people have access to adequate food, clean water, safe sewage disposal, vaccine use This leads to… Higher average life expectancy = the average length of time that an individual is expected to live Lower infant mortality = the death rate of infants less than a year old

The Demographic Transition The demographic transition is the general pattern of demographic change from high birth and death rates to low birth and death rates Observed in the history of more- developed countries Theory behind it: industrial development causes economic and social progress that then affects population growth rates

4 Stages of the Demographic Transition Model Stage 1: preindustrial society; high birth and death rates; population size is stable Stage 2: transitional society; low death rates (improved health, etc.), still high birth rates; population grows very fast Stage 3: industrial society; birth rates slow down, still low death rates; population size stabilizes population is much larger than before the demographic transition Stage 4: postindustrial society; birth rate drops below replacement level; size of the population begins to decrease Demographic Transition takes 1-3 generations to occur

4 Stages of the Demographic Transition Model

Women and Fertility: What causes the Demographic Transition? The factors most clearly related to a decline in birth rates are increasing education and economic independence for women. In the demographic transition model, the lower death rate of the second stage is usually the result of increased levels of education. Educated women… do not need to bear as many children to ensure that some will survive learn family planning techniques contribute to their family’s increasing prosperity spend less energy bearing and caring for children