Human Populations
3.1.1-3.1.4
Chapter 8, p165-181
Current Population
• Humans are currently experiencing a
phase of exponential growth (aka a J
growth curve).
• Write this value down –
• World Population Clock
• Economist Thomas Malthus first
proposed that there is a limit to the
size of a population, and that when it is
in exponential growth it will inevitably
result in a crash.
• This would represent the loss of billions
of lives
• A mild dip would be a loss of millions of
lives
Think…
• Can the human population continue on its
current trajectory?
• Why or why not?
• What are the limits to human population?
• What do you think the carrying capacity is?
• What are the implications to the planet if human
population continues to grow “unchecked”?
Limits to Population Size
• Humans rely on food, water, shelter, space, and energy to
survive. In some areas of the world, limits to one of these
resources limits population size.
• As population increases more pressure is put on the
environment for increased resources.
MORE PEOPLE NEED MORE RESOURCES
MORE MORE MORE!
Demographics
• The study of dynamics of population change.
• As populations expand, not only are we demanding more
resources, we are creating more waste and degrading the
environment.
• Human Development Index (HDI) is a measure of “well-being”
of a country based on life expectancy, GDP, education, and
standards of living.
• Typically, MEDCs have a higher HDI than LEDCs.
• 20% of world population is MEDC, 80% is LEDC
Measures of Pop Change
• Four main factors that affect population size are birth rate,
death rate, immigration, and emmigration.
• Measured by
• Crude Birth Rate (CBR): number of births per thousand
individuals in a population per year.
• Crude Death Rate (CDR): number of deaths per thousand
individuals in a population per year.
• Birth or Death Rate divided by population size times 1,000
• Natural Increase Rate (NIR): the rate increase as a percentage.
This neglects the effects of migration
• (crude birth-crude death)/10
• Doubling Rate: time in years for a population to double in size.
• An NIR of 1% will make a population double in 70 years
• Doubling = 70/NIR
Region
Land
Pop
Area
Births
(10^6) (km^2 x (10^6)
10^6)
Deaths
(10^6)
World
6000
131
121
55.8
Asia
3500
31
88.2
29.4
India
1000
3
29
10
Africa
730
29
30.7
10
Tanzania
30
0.9
1.3
0.4
Europe
730
22.7
8.5
8.2
Switzerland
7
0.04
0.09
0.07
N America
460
21.8
9.3
3.6
USA
270
9.6
4.3
2.4
CBR
CDR
NIR
Pop
Density
Region
Land
Pop
Area
Births
(10^6) (km^2 x (10^6)
10^6)
Deaths
(10^6)
CBR
CDR
NIR
Pop
Density
World
6000
131
121
55.8
20.2
9.3
1.087
45.8
Asia
3500
31
88.2
29.4
25.2
8.4
1.680
112.9
India
1000
3
29
10
29.0
10.0
1.900
333.3
Africa
730
29
30.7
10
42.1
13.7
2.836
25.2
Tanzania
30
0.9
1.3
0.4
43.3
13.3
3.000
33.3
Europe
730
22.7
8.5
8.2
11.6
11.2
0.041
32.2
Switzerland
7
0.04
0.09
0.07
12.9
10.0
0.286
175.0
N America
460
21.8
9.3
3.6
20.2
7.8
1.239
21.1
USA
270
9.6
4.3
2.4
15.9
8.9
0.704
28.1
Why do people have large families?
1.
2.
3.
4.
5.
High infant and childhood mortality
Security in old age
Children are an economic asset in agricultural societies
Status of women
Unavailability of contraception
How to reduce family size:
1. Provide education
2. Improve health
3. Provide contraception
4. Increase family income
5. Improve resource management
Population Pyramids
• Show how many individuals are alive in different age groups in
a country for any given year.
• Population on x and age on y
Demographic Transition Model
• Describes the patters of decline in mortality and fertility
nationally of a country as a result of social and economic
development.
• Stages are:
1.
2.
3.
4.
5.
Pre-Industrial Society: high birth, high infant mortality, large
families, high death
LEDC: death drops as health and sanitation improve, lifespan
increases, high birth, lowering infant mortality
Wealthier LEDC: birth rate continues to fall, population starts to
level, family size decreases, low infant death
MEDC – low birth and death rates. Stable population.
MEDC – population may not be replaced as fertility rate is low.
Problem of aging workforce.
Criticism
• This model is heavily criticized. Why?
• Not all countries follow this progression and some progress
very rapidly.
• Thought to be too heavily European based.
• Suggests that all countries go through these stages, neglecting
culture.
• The advent of large cities has also created slums with poor
sanitation and health care.
• Assumes increase in education and contraception will
decrease birth rates. Ignores religious and cultural practices.
• Eurocentric model, assumes all countries will become
industrialized.