Key Issue Number Three

Why Is Population Increasing at Different Rates in Different Countries?

This is a demographic transition model.

• Demographic Transition
• A process of change in a society's population.
• The demographic transition  diffuses to individual countries at different rates and produces local variations in natural increase, fertility, and mortality.
• Stages of Demographic Transition
• Stage One: Low Growth
• Crude birth rates and crude death rates vary while the natural increase rate was essentially zero.
• Agricultural Revolution - the time when human beings first domesticated plants and animals and no longer relied entirely on hunting and gathering.
• Stage Two: High Growth
• Crude birth rates remained while crude death rates fell rapidly. This results in a rapid rise of natural increase.
• Industrial Revolution - a conjunction of major improvements in industrial technology that transformed the process of manufacturing goods and delivering them to market.
• Medical Revolution - a conjunction of major improvements of medical technology and medical practices.
• Stage Three: Moderate Growth
• Crude birth rates dropped dramatically while crude death rates slowly continued to decrease. This results in a dramatic fall of natural increase.
• Stage Four: Low Growth
• Crude birth rates and crude death rates level out and begin to slowly increase. This results in dramatic fall of natural increase.
• Zero Population Growth (ZPG) - when the crude birth rate declines to a point where it equals the crude death rates, resulting in the natural increase approaching zero.
• Population Pyramids - bar graphs which displays country's population by displaying age and gender in groups.

This is an example of a population pyramid.
• Sex Ratio - the number of males per hundred females in the population.

If you click on the following link, you will come to a website which was written by Matt Rosenberg about population growth.

http://geography.about.com/od/populationgeography/a/populationgrow.htm