human population dynamics
TRANSCRIPT
HUMAN POPULATION DYNAMICS
See World Population Video
• What do you think? Video
Did you Know?
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How many people are on Earth?
• 6,788,977,211 (6.8 billion)
• How many people are in the U.S.?
– 308 million
• How much is 6.8 billion?
– See next slide for an exercise
Pop Census
How long would it take you to put 6.8 billion dots on a piece of paper?
• Take out a piece of paper and pen or pencil.
• Count the number of dots you can put on a piece of paper in 5 seconds (have a partner time 5 sec).
• Calculate Dots/minute (x12), dots/hour (x60), dots/day (x24), dots/year (x365).
– 6.8 billion dots divided by dots/year
POP 6800000000
DOTS/5s 26
YEARS 41.47
Note: 77 million more people added per year you were putting dots
How many people are on Earth?
• How much is one billion?
– How long is 7.8 billion seconds?• 1 billion seconds is 31 years, 8.5
months!
• 6.8 billion = 215 years, 7.5 months!
History of Human Pop Growth
• 1804: 1 billion (took a looong time)
• 1927: 2 billion (took 123 years more)
• 1960: 3 billion (33 years)
• 1974: 4 billion (14 years)
• 1987: 5 billion (13 years)
• 1999: 6 billion (12 years)
• ????: 7 billion (? Years)
History of Human Pop Growth
Population Growth Rates
Future of Human Pop Growth?
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Future of
Human Pop
Growth?
Population Density
Average Annual Rate of Change
Current Pop Growth Rate
• 10
• 9
• 8
• 7
• 6
• 5
• 4
• 3
• 2
• 1
• 0
41 people were born
• 18 people died
• = 23 people added to Earth
During this class… 39,244 born; 17,187 died; 22,058 people added
In these 10 seconds…
World Clock
Current Pop Growth Rate
• 1.15% annual growth
– What does this mean?
– Use Rule of 70 to determine Doubling Time
Type of Pop Growth
• Exponential Growth: J Curve
– Occurs when pop is growing at a percent annual growth (versus some fixed amount).
Power of exponential growth:paper folding example
# Folds Thickness
20
30
40
50
332 feet
64 miles
65,943 miles
67.5 million miles
Using 0.0038” for paper thickness (20 lb test) = 263 sheets/inch.
10 3.9 inches
Rule of 70 to determine Doubling Time
• 70 divided by % Annual Growth = Doubling Time (i.e., how long it takes for the population to double)
Rule of 70: Example 1
• Example: 10% annual growth rate
• Current population is 1 million
• How long will it take to reach:
– 2 million?
• 70/10 = 7 years
– 8 million?
• 7 X 3 doubles = 21 years
Rule of 70: Example 2
• Example: 1.15% annual growth rate
• Answer: 70/1.2 = 61 years for population to double in size
• So… in 61 years, at this rate, we will have twice as many people on Earth!
Exponential Growth
http://dieoff.org/page80.htm
What should have been done?
Exponential Growth
What should wildlife managers do?
Hunt themAdd predatorsMove themDo nothing (let them starve)
Here’s another population
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1
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1800 1850 1900 1950 2000
Year
Po
pu
lati
on
(in
bil
lio
ns)
What did you say we should do?
Biotic Potential vs. Environmental
Resistance
• One pair of cats adds up to (assumes no deaths):
• First yr: 12
• Second yr: 66
• Third yr: 382
• Fourth yr: 2201
• Tenth yr: 80,399,780
Carrying Capacity
• MAXIMUM number of individuals an area can support FOREVER.
• Law: Thou shalt not exceed the carrying capacity, for long.
– As the caribou found out
Carrying Capacity
• What is the carrying capacity for people on Earth?
Cultural Carrying Capacity
• Maximum number of individuals an area can support forever AT A GIVEN STANDARD OF LIVING.
What determines whether a population size changes?
• Rate of Increase = (Birth Rate +Immigration) – (Death Rate + Emigration)
• Age Structure = age and sex proportions in a population
• Total Fertility Rate = average # of children a woman has in her lifetime.
• Replacement Level Fertility Rate = average # of children a couple must have to replace themselves.– 2.1 in MDCs and 2.5 in LDCs
Fig. 4.8
AGE STRUCTURE
TOTAL FERTILITY RATE
Factors affecting birth rates
• Education
• Affluence
• Religious/cultural norms
• Role of women in society
• Infant mortality rates
• Availability of birth control
• Life Expectancy = how long an individualis expected to live once they are born.
What determines whether a population size changes?
Table 4.3
• Life Expectancy = how long an individualis expected to live once they are born.
WHAT FACTORS DO YOU THINKINFLUENCE LIFE EXPECTANCY?
What determines whether a population size changes?
Fig. 4.7
Human Population Growth and the Environment
• Who has a greater impact on the environment?
– Lesser Developed Countries??
– More Developed Countries??
Two Types of Overpopulation
• People Overpopulation• Consumption Overpopulation
• Who has greater impact on the environment – Lesser Developed Countries with 80% of the people or More Developed Countries using high percentage of the resources?
Fig. 4.4
Population Growth Rates
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Questions
• How does population growth affect our world today?
• What will happen in the future if we do not control population?
• What are the options for controlling population? Pros and Cons:
– Volunteer vs Forced
• How should we control population?
If we could shrink the earth's population to a village of precisely 100 people,
with all the existing human ratio's remaining the same, there would be:
• 57 Asians
• 21 Europeans
• 14 from the Western Hemisphere, both N and S
• 8 Africans
• 52 would be female
• 48 would be male
• 70 would be nonwhite
• 30 would be white
If we could shrink the earth's population to a village of precisely 100 people,
with all the existing human ratio's remaining the same, there would be:
• 70 would be non-Christian
• 30 would be Christian
• 6 people would possess 59% of the entire world's wealth and
• all 6 would be from the United States
If we could shrink the earth's population to a village of precisely 100 people,
with all the existing human ratio's remaining the same, there would be:
• 80 would live in substandard housing
• 70 would be unable to read
• 50 would suffer from malnutrition
• 1 would be near death; 1 would be near birth
• 1 (yes only one) would have a college education
• 1 would own a computer
• If you woke up this morning with more health than illness, you are more fortunate than the million who will not survive this week.
If you have never experiencedthe danger of battle,
the loneliness of imprisonment,the agony of torture,
or the pangs of starvation,you are ahead of 500 million
people in the world.
If you have food in the refrigerator,
clothes on your back,
a roof overhead
and a place to sleep,
you are richer than 70% of this world.
If you have money in the bank, in your wallet, and spare
change in a dish someplace, you are among the top 8% of
the world's wealthy.
If you can read this message,
you are more fortunate
than over two billion people in the world
that cannot read at all.
Did you Know?
THE FACTS ON CONSUMPTION
• Which world region consumes the most energy per person?
•Average energy use per person is 9 times greater in more developed than less developed regions.
•North Americans consume far more energy than any other region.
THE FACTS ON CONSUMPTION
• Which world region consumes the most energy per person?
In 2005, per capita energy use among Americans was
•2x that of Europeans
•8x that of Developing Countries
