Using Population Pyramids to Interpret & Understand Population Momentum

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  • 0:00 Population Pyramids
  • 1:03 Growing Fast in Nigeria
  • 2:08 Staying Steady in Britain
  • 3:04 Shrinking in Japan
  • 3:57 Importance of Gender
  • 4:54 Lesson Summary
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Lesson Transcript
Instructor: Kevin Newton

Kevin has edited encyclopedias, taught middle and high school history, and has a master's degree in Islamic law.

Population pyramids are among the most useful graphs for interpreting demographic data. This lesson shows how they are used, as well as demonstrating how population momentum looks on them.

Population Pyramids

For people looking at the demographics of a country or region, sheer population size alone is not enough to make a determination about any sort of long-term plans. For example, on the surface of things, a comparison between Nigeria and Japan would leave someone to think that the two countries will be evenly matched in terms of population for quite some time. However, when we look at the numbers of people per age, we see that such a case is definitely not likely. The tool used to look at different populations with respect to age and gender is a population pyramid.

When looking at a population pyramid, you'll notice that it is often split down the vertical axis into two halves. One side is for males, and the other side is for females. Also, you'll notice ranges of numbers going up that same axis. Those are the age groups. The bigger the bar next to the age group, the more people of that age and gender in the country in question.

Growing Fast in Nigeria

Nigeria is a country of 136 million people in West Africa and is currently undergoing a population explosion. More than four million new Nigerians are born every year, and that growth has no sign of stopping. As a result, the biggest bars to be found in Nigeria are all near the bottom. Also, due to the narrowness at the top, we can see that Nigeria has pretty high death rates. This is called an expanding pyramid, because the pyramid is constantly getting bigger due to the fact that the population of Nigeria is expanding. In five years, each bar will 'bump' up one, growing both the population and the size of the pyramid. However, as you can see from the graph, the birth rate is so fast as to cause the total population to grow by leaps and bounds.

You most often see this type of pyramid in developing countries, although some newly developed countries also have it - Iran is a great example of this. That said, population pyramids like this are most often found in Africa, Asia and South America.

Staying Stead in Britain

Eventually, such rapid population growth teeters out, and the population only grows by a percent or two per year. This is a sign of a highly developed economy - central to this is the idea is that women are working and only having one or two children rather than the larger families seen in developing societies. As a result, the bars have much more equal sizes. A few people are lost as the bar moves up due to premature deaths, but more are added due to immigration. These stationary pyramids don't move much, and this is ideal for a planner. As we can see in this population pyramid for the United Kingdom, the population has been quite stable over the past few years.

These stationary pyramids are most often found in areas where there has been a considerable history of development. As a result, they are most often found in the societies of North America, Western Europe and Australia.

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