chapter 9 the human population. chapter 9 big idea the size and growth rate of human population has...
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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 transitionTRANSCRIPT
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?