Environmental Science 101
Human Population: Demographics
Demography is the study of human populations.
demo- (Greek) means:
-graphy (Greek) means:
The study of populations has become more urgent recently for three
1) More people are alive today than at any time in the past.
2) The world's population has been increasing at a more rapid rate since WWII than at any time prior.
3) Virtually all global population growth is concentrated in poor, underdeveloped regions.
Demographics uses a number of statistical and graphic tools to understand various aspects of population.
1. Population Distribution
People are not evenly distributed over the surface of the Earth.
75% of the world's population lives on 5% of the Earth's surface.
Factors which influence population distribution:
1) location of rivers and potable water.
2) proximity to oceans (trade routes and natural resources)
3) location of habitats that are unable to support large populations
- mountains, deserts, tundra, dense tropical rainforests
4) location of arable soil, mineral resources
5) employment opportunities.
2. Population Density
Defined as the number of people per unit area
Defined as the total number of people divided by the total land area.
Defined as the total number of people per unit area of arable land.
India's Population =
Total Land Area =
Arable Land Area =
Arithmetic Density =
3. Population Growth
Factors which influence population growth:
A) Natural Increase Rate
- percentage by which a population grows in a year.
B) Total Fertility Rate
- average number of children a woman would have throughout her child bearing years.
E) Life Expectancy
- average number of years a newborn can expect to live.
4. Demographic Transition
Population changes which are related to stages of development.
Categorized in 4 Stages
5. Population Pyramids
Graphical display of gender and age in a population
The shape of the pyramid is primarily determined by the crude birth rate