Chap. 9: The Human PopulationSect. 1: Studying Human

PopulationsKey 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 atall

ages

Type III: poor developingcountries, most

people die veryyoung, high infant mortality rate

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

Migration 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

areaHistorical

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 deathrate 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