human population dynamics. us –310,241,523 (net gain of 1 person every 11 seconds) world...
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Human Population Dynamics
• US– 310,241,523
(Net gain of 1 person every 11 seconds)• World
– 6,868,672,761
Current Population
World Population Distribution
World Population Density
61%13%
12%
9%5%
0.5%Asia
Africa
Europe
Northern America
South Americaand Carribbean
Oceania
Historical Population Sizes
Historical Population Changes• 3 surges in
population– Tools and fire– Agricultural
Revolution– Industrial and
Medical Revolution
• Rapid growth in past ~100 years due to decrease in death rate– Increased nutrition (more food, better
distribution)– Improvements in medical technology– Improvements in sanitation and personal
hygiene– Safer water supplies
Recent Population Changes
• Change = (crude birth rate + immigration) – (crude death rate + emigration)
• % change = (crude birth rate - crude death rate)/10
• Current world growth rate = 1.1%– Increase of 76 million per year
Population Change
• High income, highly developed
• Middle income, moderately developed(upper & lower)
• Low income, developing
Different Worlds
• Replacement Level Fertility (RLF)– Couple has enough children to replace
themselves– RLF = 2.1 required to replace each generation
• Total Fertility Rate (TFR)– Total number of children a woman will have in
her life
Fertility Rates
Country TFR Doubling Time (years)
World 2.8 54
Developing Countries 3.1 44
Niger 7.5 23
Brazil 2.2 54
Developed Countries 1.6 700
US 2.0 117
Germany 1.7 ---
Fertility Rates
• What if TFR < 2.1? – Population decline– Population aging
• In US, 66% of growth by 2050 from immigrants and their descendants
Fertility Rates
• Growth rate has decreased
• However, population still increasing - rapidly
Growth Rate
• 950 CE to 1600 650 years• 1600 to 1800 200 years• 1800 to 1925 125 years• 1925 to 1975 50 years• 1975 to 2025 50 years
Doubling Time
• If a population has a growth rate of 2.0%, what is its doubling time?
• If a population has a doubling time of 14 years, what is its growth rate?
Calculating Doubling Time
Population Projection
Population Profiles
Population Profiles
Demographic Transition• Process occurring
during last ~100 years
• Stabilization of population growth in highly developed nations
• Factors influencing transition1. 2. 3.
Demographic Transition
Demographic Transition• Phase I
– Common Characteristics?
– NET RESULT =
• Countries?– Brazilian tribes?
Demographic Transition• Phase II
– Common Characteristics?
– NET RESULT =
• ex. Nepal, Afghanistan , Sub-Sahara Africa– Niger– Burundi– Tanzania
Demographic Transition• Phase III
– Common Characteristics?
– NET RESULT =
• Ex. China
Demographic Transition• Phase IV
– Common Characteristics?
– NET RESULT =
• Ex: US, England
• Phase V?
– Characteristics?
– Consequences?
• Ex: Japan, Germany
Demographic Transition