Population Pyramids (Cambridge (CIE) IGCSE Environmental Management): Revision Note

Population structure

• Population structure describes the composition of a population by age and sex

• It shows how many males and females are in different age groups

• Population structure affects the demand for services such as schools, hospitals and pensions

• Governments use population structure data to plan for the future

Age groups within a population

• Young dependants are people aged 0–14 who rely on adults for food, housing and education

• Working population includes people aged 15–64 who are economically active and support the economy

• Elderly dependants are people aged 65 and over who may require healthcare and pensions

• The ratio of the female and male population

• One of the main tools used to show population structure is a population pyramid

Interpreting population pyramids

What is a population pyramid

• A population pyramid (also known as an age structure graph) is used to display the gender and age structure of a given population

• Age groups are shown on the vertical axis, usually in five-year bands

• Males are shown on the left and females on the right

• The width of each bar represents the size of the population in that age group

• As countries develop, the shape of the population pyramid changes 

Types of population pyramid

Expansive population pyramids

• Expansive pyramids have a wide base and a narrow top

• They show high birth rates and a large young population

• Death rates may be high and life expectancy is often lower

• Common in many low-income or developing countries

• These countries may face pressure on schools, healthcare and employment in the future

  • Examples include Nepal and Niger

Stationary population pyramids

• Stationary pyramids have a more even, rectangular or bell shape

• Birth rates and death rates are both low

• The population grows slowly or remains stable

• Common in more developed countries with good healthcare and education

  • Examples include Italy and the USA

Constrictive population pyramids

• Constrictive pyramids have a narrow base and wider middle or upper sections

• They show low birth rates and an ageing population

• Life expectancy is high

• These countries may face labour shortages and increased pressure on healthcare and pensions

  • A good example is Japan with its ageing population

Migration population pyramids

• In some countries, migration can lead to an imbalance in the population structure

• The UAE has significantly more males than females 

• Approximately 29% of the population are males between the ages of 25 and 39, whereas only 10.5% of the population are women between 25 and 39

  • This is the result of the migration of males to the UAE to work in the oil, gas and construction industries

Why population pyramids are useful

• They help identify future population growth or decline

• They show the size of the future workforce

• They highlight dependency ratios

• They help governments plan for education, housing and healthcare