270 likes | 797 Views
A way of predicting population changes. Age structure diagrams. POPULATION STRUCTURE The population pyramid displays the age and sex structure of a country or given area. FEMALES To the right. MALES To the left. Population in Five Year Age bands. Usually, but not always,
E N D
A way of predicting population changes Age structure diagrams
POPULATION STRUCTURE The population pyramid displays the age and sex structure of a country or given area FEMALES To the right MALES To the left Population in Five Year Age bands Usually, but not always, In % to make for easier comparisons between countries
What Population Pyramids Show Us KEY Economically More Developed Country Economically Less Developed Country 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
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
Male Female Rapid Growth Guatemala Nigeria Saudi Arabia Slow Growth United States Australia Canada Zero Growth Spain Austria Greece Negative Growth Germany Bulgaria Sweden Ages 0-14 Ages 15-44 Ages 45-85+ Age Structure Diagrams
Predict the future population change for each of the three age structure diagrams U.S. Population by age 1900, 2000, and 2050 projected
Population structure by age and sex in developed and developing countries.
1766-1834 Thomas Robert Malthus
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 capacity • If yes, what should be done? What is a sustainable population?