Chapter 9
The Human
Population
Chapter 9 Big Idea
The
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, agriculturebased economies
Exponential Growth
Exponential Growth: rapid growth often seen
as J-Shaped curve on a graph
Is 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?
Population Age Structure
Male
Female
Rapid Growth
Guatemala
Nigeria
Saudi Arabia
Ages 0-14
Slow Growth
United States
Australia
Canada
Ages 15-44
Zero Growth
Spain
Austria
Greece
Negative Growth
Germany
Bulgaria
Sweden
Ages 45-85+
Fig. 10-14 p. 184
Forecasting Population Size
•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
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.
Population
Change = (births + immigration) – (deaths + emigration)
Migration:
movement INTO
(immigration) or OUT
of (emigration) an
area
U.S. growth
continues
because of both
births and
immigration
Population
Change = (births + immigration) – (deaths + emigration)
Death
rates on the
decline… people
living longer
Why?
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 Transition
Every Country Goes Through It
A model that describes how economic &
social changes affect population growth
rates
Demographic Transition
Every 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 Growth
In 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 Countries
US, Canada, Japan,
Australia, New
Zealand and most of
Europe. High Per
Capita GDP. (1.2
billion people)
Comparing a Developed Country
to a
Moderately Developed
to a
Developing (Least Developed)
Diverse World Population
Developing
(lesser
developed)
5.2 billion people
living with very little
97% of population
growth
Percent of
World’s
19
Population
81
Population
growth
0.1
1.6
85
Wealth and
income
Resource
use
15
88
12
75
Pollution
and waste
25
Developed
countries
Developing
countries
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?
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