AGE STRUCTURE DIAGRAMSA way of predicting population changes

POPULATION STRUCTUREThe population pyramid displays the age and sex structure of a country or given area

Population inFive YearAge bands

Usually, but not always,In % to make for easiercomparisonsbetween countries

FEMALESTo the rightMALES

To the left

What Population Pyramids Show Us

KEY

slope of pyramid indicate the death rate

width of the base is related to birth rate/fertility rate

proportions of men and women can suggest male or female migrations

height of graph can indicate life expectancy (ignore the very thin end of the wedge as occurs on graph B as these people are a definite minority)

"kinks" indicate dramatic reductions in birth rate or increases in death rate in the past

area of graph indicates total population - compare areas of differentpopulation age groups or different sex on one graph

The overall shape of the population pyramid can indicate whether it is an Economically More Developed Country or Economically Less Developed Country

Economically More Developed Country

Economically LessDeveloped Country

Population pyramid of a less developed nation (broad base population pyramid)

Population Pyramid of Nigeria (1995)

Importance of Population Pyramids

A BROAD BASE POPULATION

PYRAMID MEANS A COUNTRY SHOULD:

• increase food production• build more homes & schools• plan for more job opportunities for the young in future• implement birth control program/campaigns

•Usually agricultural population with problems of overpopulation.

Population pyramid of a developed nation

Population Pyramid of Sweden (1995)

Importance of Population Pyramids

A NARROW BASED POPULATION

PYRAMID MEANS:

Birth rate and Death rate low so a country may need to:

• Work out incentives to encourage more births• Begin hiring foreign labor• Ensure proper medical services & health care for the aged

Ages 0-14 Ages 15-44 Ages 45-85+

Rapid GrowthGuatemala

NigeriaSaudi Arabia

Slow GrowthUnited States

AustraliaCanada

Male Female

Zero GrowthSpainAustriaGreece

Negative GrowthGermanyBulgariaSweden

Age Structure Diagrams

U.S. Population by age 1900, 2000, and 2050 projected

Predict the future population change for each of the three age structure diagrams

Population structure by age and sex in developed and developing countries.

Tracking the baby-boom generation in the U.S.

THOMAS ROBERT MALTHUS

1766-1834

Growth Potential of Subsistence Vs. Population

SUBSISTENCE POPULATION0

20

40

60

80

100

120

140 TIME 1

TIME 2

TIME 3

TIME 4

TIME 5

TME 7

TIME 6

TIME 7

Basic Point From MALTHUS: Population and food supply

(subsistence) grow at different rates

Population will outgrow food supply

Results from the point of crisis include famine and war

What are advantages and disadvantages of reducing births: Controversy

Can the world’s resources support an additional 2.5 billion by 2050?

Is the Earth overpopulated?

Carrying capacityIf yes, what should be

done?

What is a sustainable population?