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Population Pyramid

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Population Pyramid: An Introduction

As we know China's population is declining, America's population is stable and India's population is growing.

Have you ever thought about how we get to know about the population size or its composition? The data are compared of different countries over time using a population pyramid. A population pyramid is a graphical representation that can be used to compare the size of the population and the population's present and future trends.

What is a Population Pyramid?

A population pyramid is the graphical representation of the distribution of the population by sex, and age group. It takes the shape of a pyramid when the population is growing. Population pyramids are also known as age pyramids because it is a graphical representation of age.

Structure of a Population Pyramid

A population pyramid is a graphical representation that demonstrates the distribution of ages across a population.

It is divided from the centre between male and female individuals. The males are shown on the left side and the females are on the right side from the centre of the graph.

The population size is shown on the x-axis and ages are shown on the y-axis.

Structure of Population Pyramid

Structure of Population Pyramid

Types of Population Pyramids

There are mainly three types of the population pyramid or population graphs

  • Expansive

  • Stationary

  • Constrictive

Expansive Pyramid

These types of pyramids have a much larger population of pre-reproductive and reproductive age groups and a population of post-reproductive age groups is very less compared to pre-reproductive and reproductive age groups.

These types of pyramids are seen in developing countries. Here in these countries, the fertility rate is usually high but life expectancy is very less. So the base of the pyramid is wide and tapers towards the top with a triangular shape.

Examples of countries having expansive pyramids are India and Nigeria.

The Expansive Population Pyramid

The Expansive Population Pyramid

Stationary Population Pyramid

Stationary population pyramids have an equal population in each group. That's why the name stationary means the birth and death rates are equal and the population is neither increasing nor decreasing. There are usually not any major changes in the mortality rate and fertility rates.

The shape of this pyramid is bell-shaped.

These types of pyramids are generally of the developed countries such as America.

The Stable Population Pyramid

The Stable Population Pyramid

Constrictive Population Pyramid

As the name itself suggests that the population is decreasing here, these types of pyramids show declining birth rates, low fertility rates, high life expectancy, and low mortality rates.

These graphs are narrow at the base and show the decreasing size of the population. These graphs are urn-shaped.

Here the post-reproductive and elderly population is more than the pre-reproductive and reproductive population.

This type of graph is seen in Japan.

The Constructive Population Pyramid

The Constructive Population Pyramid

Uses of the Population Pyramid

There are various uses of the population pyramid

  • It tells about the composition of the population of any particular area

  • It tells about the number of dependent individuals (Children, elderly people) in any area

  • It also tells us about the difference in sexes of any given area.

  • It also tells about the mortality rate and fertility rate

  • Use to find data on the future growth of the population

Interesting Points

  • Only 10% of the world's population lives in the southern hemispheres

  • The size of the European population is decreasing and the size of the African population is increasing.

  • If every female in the world received secondary schooling, the population could be 3 billion short by 2050.

Important Questions

1. What does the expansive pyramid represent?

  1. Growing population

  2. Stable population

  3. Decreasing population

  4. All of the above

Ans: (option 1) growing population. If Population size increases with time, then it is represented by an expansive pyramid.

2. What is the population pyramid?

  1. The pattern of population distribution in urban areas

  2. A graphical representation of the age, and sex composition of a given population in any area

  3. When the population density of an area is so high that people live in tall buildings

  4. None of the above

Ans: (option 2) A graphical representation of the age and sex composition of a population in a given area is called a population pyramid.

3. The age distribution of a population is determined by

  1. Timing of birth

  2. Timing of death

  3. The rate at which the population is growing

  4. All of the above

Ans: (option 3) The rate at which the population is growing is determined by the age distribution of a population.

Practice Questions

  1. What are the things that change the shape of a population pyramid?

  2. What are the three types of population pyramids?

  3. What does the shape of a population pyramid reflect?

  4. Which age pyramid is most stable and why?

  5. How can the population pyramid predict the future?


A population pyramid is a graphical representation of the distribution of people by sex and age group. There are usually three types of age pyramids - The expansive age pyramid, stationary age pyramid, and constructive age pyramid.

And all three pyramids are of different shapes. These pyramids also have various uses such as telling us about the mortality and fertility rates of any given area.

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FAQs on Population Pyramid

1. What are the stages of the population pyramid?

There are five stages of the population Pyramid: 

  1. High Fluctuating - These types of pyramids have a narrow top and wide base which reflects that there are few people in old age.

  2. Early Expansion - in this stage reproduction rate is high.

  3. Late Expanding - in this stage population size increases but the growth rate declines

  4. Low Stationery - in this stage sudden growth ends. The young population almost equal to the older population

  5. Natural Decrease - In this stage the older population is more than the juvenile population.

2. What are the three main factors that cause population change?

There are various factors that cause population change - Natality, Mortality, and migration.

  • Natality is defined as the number of live births per thousand of the population per year. It increases the present population of any given area.

  • Mortality is defined as the number of deaths per thousand population per year. It decreases the present population.

  • Migration - Movement of people in and out of any area.

  • Immigration - Movement of people inside any community or country. It increases the present size of the population.

  • Emigration - the movement of people out of any area. It decreases the present size of the population.

3. What are the characteristics of a population?

The characteristics of a population discussed below:

  • Natality - It is also known as the birth rate. The main reason for the population increase is natality.

  • Age Structure - It is defined as the number or proportion of people or individuals in each age group. The ratio of age group determines the population structure whether it is stabilising, increasing, or constricting.

  • Mortality - Is defined as the death rate. It decreases the size of the population 

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