Human Populations:
Population Dynamics IB syllabus: 3.1.1-3.1.4
Ch 12
Video: The Population Paradox – World in the Balance
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Syllabus Statements
• 3.1.1: Describe the nature and explain the implications of exponential growth in human populations
• 3.1.2: Calculate and explain, from given data, the values of crude birth rate, crude death rate, fertility , doubling time and natural increase rate
• 3.1.3: Analyze age/sex pyramids and diagrams showing demographic transition models
• 3.1.4: Discuss the use of models in predicting the growth of human populations
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vocabulary
1. Crude birth rate
2. Crude death rate
3. Demographic transition
4. Doubling time
5. Fertility
6. Rate of natural increase
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Factors Effecting Population Size
• 3 factors effecting population birth, death, & migration.
• Population change = (Birth + Immigration) – (Deaths + Emigration)
• Rates more often used.
• Crude Birth rate = # live births / 1000 people in year population.
• Crude Death rate = # deaths / 1000 people in year population
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Average crude birth rate Average crude death rate
World
All developed
countries
All developing
countries
Developing
countries
(w/o China)
21
9
11
10
24
8
29
9
© 2004 Brooks/Cole – Thomson Learning
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Africa
Latin
America
Asia
Oceania
United
States
North
America
Europe
38
14
23
6
20
7
18
7
15
9
14
9
10
11
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World Population Change
• Worldwide birth and death rates dropping
• Death rate dropping faster than birth rate
• 216,000 people added to world population daily
• Exponential population growth still occurring but slower
• http://www.census.gov/main/www/popclock.html -
Population counter
• But base number still increasing
• 79 x 106 people added per year
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World Population over the Centuries
9,000 human beings added to the
planet every hour
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<1%
1-1.9%
2-2.9%
3+%
Data not available
Annual world population growth
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Reasons for the Human Population Explosion
• Death rates dropping faster
because of
• Causes of disease
recognized
• Improvements in nutrition
• Discovery of antibiotics
• Improvements in medicine
• Increase in number of
women who actually reach
child-bearing age
Age Birth Death
A
B
Survival changed from B to A
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Implications of Exponential Growth
• Biotic potential exceeds environmental resistance: birth
rates exceed death rates
• Outstrip our resource base – nonrenewable gone,
renewable maybe used faster than replaced
• Increase strain on the environment – pollution,
sanitation needs, biodiversity loss
• Increase food production & land under production
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Average Number of Children, Grandchildren, and Great Grandchildren
• America
• West Germany
• Africa
• 14
• 5
• 258
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Fertility • Replacement fertility – number of children a
couple must bear to replace themselves – roughly
2.1
• Reaching replacement fertility now would still
cause population growth for another 50 years
• Total fertility rate (TFR)= # of children a woman
will have in her childbearing years (15-49)
• TFR = 1.6 in developed countries, 3.1 in
developing countries
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Calculating Fertility Rates and Doubling Times
(CBR – CDR)/10 = Rate of increase or decrease
in population per 1,000 per year
70/Rate of Increase = Doubling Time
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Calculating Fertility Rates and Doubling Times: Practice
Country CBR CDR Rate of
Increase
Doubling
Time
Kenya 33 13
Mexico 27 5
USA 15 9
Denmark 13 11
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Calculating Fertility Rates and Doubling Times: Answers
Country CBR CDR Rate of
Increase
Doubling
Time
Kenya 33 13 2.0 35
Mexico 27 5 2.2 32
USA 15 9 0.6 116
Denmark 13 11 0.2 431
350
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Births per woman
< 2
2-2.9
3-3.9
4-4.9
5+
Data not
available
Worldwide TFR in 2002
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High
Medium
Low
12
11
10
9
8
7
6
5
4
3
2 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050
High
10.9
Medium
9.3
Low
7.3
Year
Po
pu
lati
on
(b
illi
on
s)
Population projections based on TFR (H = 2.6, M = 2.1, L = 1.7)
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4.0
3.5
3.0
2.5
2.0 2.1
1.5
1.0
0.5
0 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Year
Bir
ths p
er
wo
man
Baby boom
(1946-64)
US fertility and the “baby boom”
32 30 28 26 24 22 20 18 16 14 0
Bir
ths
pe
r th
ou
sa
nd
po
pu
lati
on
1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Year
Demographic
transition Depression
End of World War II
Baby boom Baby bust Echo baby boom
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Factors effecting Birth & TFR 1. Importance of children for
labor higher in developing countries & rural areas
2. Urbanization more family planning resources, less need for children in cities
3. Cost of raising or educating children more expensive to raise in developed areas
4. Education & Employment for women less opportunity outside of house higher TFR
5. Infant mortality rate When infant mortality lower fewer children needed
6. Average age at marriage Fewer children when 25 or older for marriage
7. Availability of pension Eliminate need for kids to take care of you
8. Availability of Legal abortion
9. Availability of & Reliability of birth Control
10.Religious beliefs, traditions, cultural norms
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Life & Death • Infant mortality and Life Expectancy are good
indicators of health in a country
• Global life expectancy is increasing
• Poorest countries it may still be low or even falling (AIDS in Africa)
• Infant mortality encompasses nutrition & health care so it’s a good measure
• Still 8 million infants worldwide dieing of preventable causes in first year of life
• US – teen pregnancy rate highest of all industrialized countries
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<10
10-35 36-70
100+
Data not available
Infant deaths per 1,000 live births
71-100
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Different Worlds
• Rich nations, poor nations
• Population growth in rich and poor nations
• Different populations, different problems
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Population (2002)
Population projected
(2025)
Infant mortality
rate
Life expectancy
Fertility rate (TFR)
%Population under
age 15
% Population over
age 65
Per capita GNI PPP
(2000)
288 million 174 million
130 million
346 million
219 million 205 million
6.8 33
75
77 years
69 years 52 years
2.1 2.2
5.8
21% 33%
44%
13%
5% 3%
$34,100
$7,300
$800
United States (highly developed)
Brazil (moderately developed)
Nigeria (less developed)
© 2004 Brooks/Cole – Thomson Learning
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Economic Categories Based on Per Capita Gross National Income
• High-income, highly developed, industrialized countries
• United States, Japan, Canada
• Average GNI per capita = $26,710
• Middle-income, moderately developed countries
• Latin America, South Africa, China
• Average GNI per capita = $1,850
• Low-income, developing countries
• Western and central Africa, India, central Asia
• Average GNI per capita = $430
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Disparities
• Developed countries
• 16% of the world’s population
• Control 81% of the world’s wealth
• Low-income developing countries
• 41% of the world’s population
• Control 3.4% of the world’s gross national income
• Difference in per capita income: 62 to 1!
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Population Increase in Developed and Developing Countries
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Developed Countries
50
40
30
20
10
0 1775 1800 1850 1900 1950 2000 2050
Rate
per
1,0
00 p
eo
ple
Year
Rate of
natural increase
Crude
birth rate
Crude
death rate
Rate of natural increase = crude birth rate – crude death rate
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Developing Countries
50
40
30
20
10
0 1775 1800 1850 1900 1950 2000 2050
Rate
per
1,0
00 p
eo
ple
Crude
birth rate
Rate of
natural
increase Crude
death rate
Year
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Population Age Structure
• Analysis by sex, of the proportion of population at each age level
• 3 main age categories • Prereproductive: 0 – 14 years
• Reproductive: 15 – 44 years
• Postreproductive: 45 and up
• Represent a good comparison between countries
• Compare Growth Rapid, Slow, Zero, Negative
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Male Female
Rapid Growth
Guatemala
Nigeria
Saudi Arabia
Slow Growth
United States
Australia
Canada
Male Female
Ages 0-14 Ages 15-44 Ages 45-85+
© 2004 Brooks/Cole – Thomson Learning
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Zero Growth
Spain
Austria
Greece
Negative Growth
Germany
Bulgaria
Sweden
Male Female Male Female
Ages 0-14 Ages 15-44 Ages 45-85+
© 2004 Brooks/Cole – Thomson Learning
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Age Structure & Population Growth
• Country with many people under 15 has large potential for population increase.
• Depends on the number of females as well
• In 2002 30% of world population was below 15 (33% in developing countries)
• Population has stabilized or declining in most developed countries
• Many developing countries expected to double or triple before stabilizing
• Mexico, Ethiopia, Nigeria, Pakistan, Brazil
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Population Momentum
• Countries like Iraq will continue to grow for 50–60 years even after the total fertility rate is reduced to replacement level.
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Projections of Population and Economics • Track the baby boomers through age pyramids
• Currently ½ of adult Americans
• Dominate demand for goods, services, & control politics and laws
• The social security problem – Paid for by current workers, fewer
than boomers
• Future impact = later retirement, more taxes, …
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20
Age
Females Males
1955
16 12 8 4 4 8 12 16
20
Millions
Age
24 20 16 12 8 4 4 8 12 16 20 24
Females Males
1985
Millions © 2004 Brooks/Cole – Thomson Learning
Age
Females Males
2015
20 16 12 8 4 4 8 12
16 20 20
Millions
Age
24 20 16 12 8 4 4 8 12 16 20 20
Females Males
2035
Millions
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1945
41.9 workers
40
30
20
10
0
1950
16.5
2075
1.9
1945 2000 2050 2075
Nu
mb
er
of
wo
rkers
su
pp
ort
ing
each
So
cia
l S
ecu
rity
ben
efi
cia
ry
Year
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Problems with Population decline
• If many populations stable now
• At some future time they will begin to decline
• By 2050 – 39 countries are expected to be in decline
• If rapid, can cause problems (1) consume public services,
health care, social security; (2) labor shortage, increased
reliance on immigrant labor
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40
35
30
25
20
15
10
5
0
1950 1970 1990 2010 2030 2050 2070 2090 2110 2130 2150
Year
Ag
e D
istr
ibu
tio
n (
%)
Under age 15 Age 60 or over Age 80 or over
Global
Aging
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Population decline from rising death rates
• HIV epidemic in Africa kills 6000 daily
• Kills mostly young adults
• Sharp decrease in average life expectancy
• Loss of productive workers
• Rise in numbers of orphans
• Drop in food production with loss of laborers
• Need new Marshall Plan
• Reduce HIV spread: education, health services
• Restore economic progress: aid as $ & volunteers
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Is the world overpopulated?
• Wrong question?
• What is the optimum number of people that can be
sustainably supported by the earth without further
environmental degradation
• Optimum would allow people to live comfortably without
harming future generations
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Solutions
1. Reducing births!
- Violation of personal and religious freedoms
- Viewed as a form of genocide by some ethnic groups
- BUT
- We currently don’t provide basic needs for 1/6 of the world population
- Increasing environmental harm & death rates
- Life span longer today so we have a greater per person impact too
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Demographic Transition Hypothesis • As countries become industrialized first death rate then birth rate
will decline
1. Preindustrial Stage harsh living conditions = little population
growth, high B & D
2. Transitional Stage industrialization starts, better healthcare &
food = population growth is rapid, high B & lower D
3. Industrial Stage Industry continues = population grows but
slowly, B > D by a little
4. Postindustrial Stage population growth stops, B = D (13% of
world) then B < D an may start to decline (this may be stage 5)
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Low
High
Re
lati
ve
po
pu
lati
on
siz
e
Bir
th r
ate
an
d d
ea
th r
ate
(n
um
be
r p
er
1,0
00
pe
r ye
ar)
80
70
60
50
40
30
20
10
0
Stage 1
Preindustrial
Stage 2
Transitional
Stage 3
Industrial
Stage 4
Postindustrial
Low growth rate
Increasing growth rate
Very high growth rate
Decreasing growth rate
Low growth rate
Zero growth rate
Negative growth rate
Birth rate
Total population
Death rate
Time
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Demographic Transition Comparisons
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Demographic Transition Hypothesis
• Most developing countries today have death rates declining
more than birth rates
• Still in Transitional stage
• Fear that population growth in these areas will overcome
economic growth
• Demographic Trap: get stuck in a stage
• Countries lack skilled workers, capital & resources, drop in
economic assistance
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Can we reduce Birth rates
• Doing so will reduce abortion rates & save lives as well
1. Family Planning – info on birth spacing, birth control and
prenatal care
2. Empowering women – education, job opportunities, womens
rights
• Women work 2/3 all hours worked, 10% income
3. Economic Rewards & Penalties – payments to individuals who
use contraceptives
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Condom
5%
Female sterilization
17%
IUD
12%
Other
methods
10%
Pill
8%
Male
sterilization
5%
No method
43%
Global
Contraceptive Use
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India: A Case Study • World’s first national family planning program
• After 50 years it is still the second most populous country in world
(1 billion)
• GNIPP is $2,340 a year
• Unemployment = 50%
• 40% population, 50% children suffer malnutrition
• 16% world population, 2% resources
• ½ cropland degraded, 70% water seriously polluted
• Overall, program disappointing & poorly done
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China: A Case Study • 1972-2002 cut crude birth rate in half, TFR from 5.7 to 1.8 children per
woman • Encourage late marriage & 1 child per family
• Contraception. Sterilization, Abortion = FREE
• Reward Food, $$$, School tuition, Medical care
• UN projects population drop by 2042
• It was either population control or starvation
• Population still growing, mass environmental impact
• But projected to be on the decline by 2040
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Percentage of world
population
Population (2000)
Population (2025) (estimated)
Illiteracy (%of adults)
Population under age 15(%)
Population growth rate (%)
Total fertility rate
Infant mortality rate
Life expectancy
GNP per capita (1998)
16%
21%
1 billion
1.3 billion
1.4 billion
1.4 billion
47%
17%
36%
25%
1.8%
0.9%
3.3 children per woman (down from 5.3 in 1970)
1.8 children per woman (down from 5.7 in 1972)
72
31
61 years
71 years
$440
$750
India
China
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Cutting Global Population Growth
• UN encouraging world population stability
• Universal access to family planning
• Improve health care – infants, children, women
• Social & Economic plans for countries
• Increase access to education
• Eradicate poverty
• Eliminate unsustainable patterns of production and consumption
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The use of Models
• We can’t see the future
• But we have good predictive power based on current numbers
• Using birth & death rates, fertility and extrapolation we can
model populations into the future
• Models based on mathematical calculations of future
predictions
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Computer Simulations
• View Population connection simulation
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Demographic Tables
• http://www.wpro.who.int/publications/databases/demographic_tables/en/
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Projecting Future Populations: Age/Sex Pyramids
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Graphical Extrapolation: World Population
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• http://www.shambles.net/worldclock/worldclock.swf
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Review Topics
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Are these characteristics of Developing or Developed Nations?
• High fertility rates
• High consumptive lifestyles: use 80% of world’s wealth
• Intense poverty
• Eat high on the food chain
• Long doubling times
• High environmental degradation
• Twenty percent of the world’s population
• Rule of 70 – yrs it takes for pop to double Guru
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Compare Projected Populations in Developing and Developed Countries
Fertility Rate
> 2
Fertility Rate
< 2
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Consequences of Exploding Populations
More Population
Causes MORE
LESS
deforestation
resource depletion
loss of agricultural land
disease
population migration
Irrigation
biodiversity
pest resistance
wetlands
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