Chapter 9The Human Population

Chapter 9 Big IdeaThe size and growth rate of

human population has changed drastically over the last 200 years. Those changes have led to profound changes to almost every place on Earth.

Section 1: Studying Human Populations

Describe how the size and growth rate for human population has changed over history

What factors lead to population changes Analyze populations using Age Structure

Diagrams Define demographic transition

• Describe what you see on this graph• How long did it take to get to 1 billion, then 2, 3, 4,

5, 6?• How many people are living today?

• Why do you think population took off around the late 1880s?

Rapid population growth has led to serious environmental problems

Studying Human Populations Demography: the

study of human population

How many people live where?

How long are you expected to live?

How many children are you likely to have.

2 General Categories of Populations

Developed Countries– Higher average

income– Slower population

growth– Diverse industrial

economies– Stronger social support

systems

Developing Countries– Lower average incomes– Rapid population growth– Simple, agriculture-

based economies

Exponential Growth

Exponential Growth: rapid growth often seen as J-Shaped curve on a graphIs exponential growth sustainable?

Forecasting Population Size Will new schools be

needed? Should we be

building more housing?

Should farming practices be improved?

Predictions like this often wrong because human behavior changes

POPULATION SIZE

http://www.worldometers.info/world-population/

Forecasting Population Size Age Structure: the

distribution of ages in a population

Age Structure Diagrams aka Population Pyramids

What is useful about these diagrams?

• What do age structure diagrams show?• What are the “reproductive years”?• Why is that important in forecasting future population growth?

• Which “type” of countries are going to see most of the population growth?

• Which “type” of countries do people live longer lives?

Ages 0-14 Ages 15-44 Ages 45-85+

Rapid GrowthGuatemala

NigeriaSaudi Arabia

Slow GrowthUnited States

AustraliaCanada

Male Female

Zero GrowthSpainAustriaGreece

Negative GrowthGermanyBulgariaSweden

Population Age Structure

Fig. 10-14 p. 184

• Survivorship: percent of population likely to survive to any given age

• Survivorship Curves – show how much of the population survives for a given age

• Type I• Wealthy, developed countries• Most people live to be very old

• Type II• Similar death rates at all ages

• Type III• Very poor, undeveloped countries• Many children die

Forecasting Population Size

PROJECTED WORLD POPULATIONS

What causes population to rise?Population Changes =

(births + immigration) – (deaths + emigration)

For world population growth we are only concerned about births and deaths.Many developed countries would have negative population growth without immigration.

Migration: movement INTO (immigration) or OUT of (emigration) an area

Population Change = (births + immigration) – (deaths + emigration)

U.S. growth continues because of both births and immigration

Death rates on the decline… people living longer

Why?

Population Change = (births + immigration) – (deaths + emigration)

Better hygiene, sewage disposal, clean water, medicines, education, access to food, nutrition

Life Expectancy Life Expectancy:

average number of years members of a population are expected to live

Improvement in most of world

Lower INFANT MORTALITY

Compared to our neighbors

Major changes in U.S. over last 100+ years

Fertility Rates

Fertility Rate: number of children born each year per 1,000 women

Total fertility rate (lifetime)

Replacement level

• What does this graph show?• (Total Fertility Rate – average number of births in one woman’s

lifetime• How have U.S. fertility rates changed?

Fertility and Women Two main factors

impact fertility rates worldwide

Education level of women (knowledge of family planning)

Economic level of women

Generally : more education =

more wealth = lower fertility rates

Demographic TransitionEvery Country Goes Through It

A model that describes how economic & social changes affect population growth rates

Demographic TransitionEvery Country Goes Through It

Explain what you see on this chart

• Stage 1 : High Birth AND Death rates = little population change• Stage 2 : Death Rates Fall, Birth Rates Still High = Population Growth

• Stage 3: Death Rates Low, Birth Rates Drop = Population Growth Slows• Stage 4: Death Rates Low, Birth Rate Low = Population Declines

DESCRIBE EACH STAGE: WHAT DO YOU SEE?

Calculations A town currently has a population of

20 people. If 10 people are born, 8 people die, 3 immigrate and 1 emigrate, what is the population?

Calculations USA currently has a population of

320,000,000 people. If 5,000,000 people are born, 2,000,000 people die, 200,000 immigrate and 50,000 emigrate, what is the population?

Rule of 70: Doubling Time Currently, a city has a population of 10 million.

If the population is growing at 10%, when will it reach 20 million? (70/rate = doubling time)

What is the growth rate if the population increases from 200 million to 400 million in 14 years ? (70/doubling time = rate)

Section 1 Review Describe how the size and growth rate for

human population has changed over history

What factors lead to population changes Analyze populations using Age Structure

Diagrams Terms: Demography, Age Structure,

Survivorship, Fertility, Migration, Life Expectancy

Section 2 : Population Trends What are the problems associated

with rapid human population growth? Compare developed and developing

(less developed) countries Investigate strategies for reducing

population growth

Problems With Rapid Growth

Lack of infrastructure to support population

Water supplies Sewers Roads Schools Power Plants Hospitals Housing

Problems With Rapid Growth

Using up resources too quickly

Water supplies Vegetation

– Food supplies – Wood/fuels : wood

supplies critical to life in many regions

Land

Problems With Rapid Growth

Shortage of Fuel Wood

Supply of fuel ensures– Boiled water– Cooked food

Problems With Rapid Growth

Unsafe water supplies

Sewage mixing with water supplies– Cholera– Dysentery– Typhoid

1 billion lack clean water

3 million/yr die

Clean Water Lacking

If the millions of women who haul water long distances had a faucet by their door, whole societies could be transformed.

Problems With Rapid Growth

Land becomes scarce Arable land : land

that can grow crops Trade-offs made:

– agriculture, housing, natural habitats

Which do you think typically wins out?

Problems With Rapid Growth

Urbanization: movement of people from rural areas to cities

Much of world is going through

Increased demand on infrastructure

Problems With GrowthIn U.S.Suburban sprawl:

work in cities live in suburbs– Decay of inner cities– Increased traffic– Loss of farmland– Decreased wildlife

habitat

Suburban Sprawl

Diverse World Population

Developed CountriesUS, Canada, Japan,

Australia, New Zealand and most of Europe. High Per Capita GDP. (1.2 billion people)

Comparing a Developed Countryto aModerately Developedto aDeveloping (Least Developed)

Diverse World Population Developing (lesser

developed) 5.2 billion people living with very little 97% of population

growth

Percent of World’s

Developingcountries

Developedcountries

Population

Populationgrowth

Wealth andincome

Resourceuse

Pollutionand waste

19

81

0.1

1.6

85

15

88

12

75

25

World Growth Rates

Strategies for Controlling Growth Public

Advertisements Economic

Incentives Legal Punishments Empowering

Women Investments in

Education and Family Planning

Worldwide fertility rates are dropping

Growth Is Slowing but still growing

Medium growth rate – fertility rates decline to replacement level by 2050

Section 2 Review What are problems associated with

rapid human population growth? How do developed and developing

(less developed) countries compare? What are some strategies for

reducing population growth?