(September 03, 2008) Here’s an example of a population pyramid (Canada, 1961). The left side is a bar graph that describes the percentage of men in a given age bracket. The right side describes the distribution of women by age. The term “pyramid” refers to the shape of the diagram.
You can see that the pyramid narrows toward the top. This is because the death rate is higher among older 080825 Population I
In 1961, the pyramid had a wide base. In fact, when we add the percentages for the three lowest age groups, we find that 35% of the population was under 15. These are the “baby boomers,” a large group of people born between 1947 and 1966 when the economy was growing and prospering.
For the vast majority of human history, population distributions looked just like this example….Lots of young people, increasingly fewer old people.
Over the past 50 years, things have been really changing. Life expectancy has grown while family size has shrunk. There are many more older people and fewer young. Here are some examples of the kinds of pyramids that are emerging.
Finally, here’s how you use the pyramid to analyze changes in a population.
Watch some of these animations. They display the changes in the pyramid in Canada’s provinces