Chapter 7: Population Principles
= (births + immigration) - (deaths + emigration)
Birth rate =
Death rate =
"Natural" Population Change
Excludes immigration and emigration
Usually expressed as a percentage: (birth rate - death rate)/10
"Rule of 70"
E.g., U.S. has about 0.6% growth rate, so the doubling time (in years) of the population size is 70/0.6 = 117 years
Study of changes in population factors: Size, density, dispersion, age distribution
As population grows, environmental resistance increases,
Eventually, population size reaches its Carrying Capacity (K)
The more people of childbearing age and younger, the more rapid the growth rate
Age structure example:
Carrying Capacity (K)
Is NOT a simple, fixed quantity
Depends on many factors, e.g.:
How many offspring per individual - Two extremes:
Define birth rate, death rate, rate of natural change, ZPG.
What do you think is the earth's carrying capacity for humans? Why?
What factors affect the carrying capacity of an ecosystem for a particular species?
Are humans K-strategists or r-strategists? Why?
Be able to use the Rule of 70 to calculate the doubling time of a population.
How does age structure affect the growth rate of a population?
Chapter 8: Human Population Issues
Rates of Natural Increase
Highest to lowest: (doubling time)
Africa 2.5% (27 years)
Latin America 1.8% (38 years)
Asia 1.5% (46 years)
North America 0.6% (117 years)
Europe -0.1% (decreasing!)
Projected Birth Rates by Region
Natural Increase (Whole World)
1965 ===> 2.0%
1996 ===> 1.55%
Highest to lowest: (% of world)
Asia 3.6 billion (60.8%)
Africa 770 million (12.9%)
Europe 725 million (12.3%)
Latin America 500 million (8.44%)
North America 305 million (5.1%)
Replacement level fertility (RLF):
Total Fertility Rate (TFR):
TFRs - Same order of regions as growth %
Worldwide = 3.0
MDCs = 1.6
LDCs = 3.4
Goal: TFR = RLF
But, does not immediately produce ZPG
Why? (Age distribution or structure!)
Even if TFR = RLF, world's population would continue to grow for at least 50 years
Reason: Age Structure of the population
More people of childbearing age and younger, the more rapid the growth rate
"South" vs. "North"
MDCs = 22%, LDCs = 78%
Natural growth rate:
MDCs = 0.2%, LDCs (w/o China) = 2.2%
Why the big difference between MDCs and LDCs?
Factors Affecting Birth Rates
Levels of education higher in MDCs
Child labor important in LDCs
Urbanization => children not "useful"
Later marriage in MDCs
Retirement system in MDCs
Reliable birth control ???
Factors Affecting Death Rates
Decline is largely responsible for rapid growth of population over past 100 years
Modern Medicine, together with
Public Health Measures
Of overall health in a region are
Life expectancy and
Infant Mortality Rate = number of babies out of 1000 born each year that die before first birthday
IMR is probably best measure of quality of life
Demographic Transition Theory
Concept: Reducing growth rate through economic development
Four "stages": Preindustrial, Transition, Industrial, Postindustrial
Ex: MDCs and Industrial Revolution
Applying DTT to LDCs
Idea: Redistribute wealth from MDCs to LDCs (includes forgiving debt)...
LDCs will then develop better economy
They will then go through a "demographic transition"
Population growth rate will decrease
Problems with this theory?
CASE STUDIES: China and India
Urbanization - (more in chapter 13)
45% of world's population lives in cities
50% by 2005
60% by 2025
MDCs: 75% urban, LDCs: 37%
Most of urbanization is expected in LDCs => concentrated impact on environment, insufficient infrastructure
What is the problem with applying DTT to fast-growing LDCs?
Give four reasons that TFR is higher in LDCs than in MDCs.
Why is availability of birth control NOT the most significant reason
for overpopulation in LDCs?
Even though it does not immediately affect overall world population,
how can immigration from an LDC to the U.S. be environmentally harmful?
Why is RLF not equal to 2.0?
Why has China's population control program been effective while India's has not?
List the main regions of the world in decreasing order of rate of natural increase and
Why do you think Germany has a negative population growth rate,
while the population of the U.S. is growing by 0.6% annually?