Population and population growth
Population means the total number of people living in a country, region or area at a particular time.
Population growth means an increase in the size of a population over time. A population grows when births and immigration are greater than deaths and emigration.
Population change = births − deaths + net migration
Births
More births increase the population.
Deaths
More deaths reduce the population.
Migration
Immigration increases population; emigration reduces it.
How to read the graph: the upward-sloping line shows that the world’s population has been rising over time. The projected section suggests that population may continue to increase, although the rate of growth can vary between countries.
1. Factors that affect population growth
Population growth depends mainly on the number of births, deaths and people moving into or out of a country.
| Factor | Meaning | Effect on population |
|---|---|---|
| Birth rate | The number of live births per 1,000 people in a year. | A higher birth rate increases population growth. |
| Fertility rate | The average number of children a woman is expected to have during her lifetime. | A higher fertility rate usually means faster future population growth. |
| Death rate | The number of deaths per 1,000 people in a year. | A higher death rate slows population growth or may reduce population size. |
| Net migration rate | The difference between immigration and emigration, usually measured per 1,000 people. | Positive net migration increases population; negative net migration reduces it. |
Useful terms
- Immigration: people entering a country to live or work.
- Emigration: people leaving a country to live or work somewhere else.
- Natural increase: when the birth rate is higher than the death rate.
- Natural decrease: when the death rate is higher than the birth rate.
2. Why population growth rates differ between countries
Population growth is not the same everywhere. Some countries have fast population growth, while others have slow growth or even a falling population.
| Reason | LEDCs | MEDCs |
|---|---|---|
| Birth rates | Birth rates may be higher because children may help families earn income, access to contraception may be limited, and infant mortality may be higher. | Birth rates are often lower because education levels are higher, the cost of raising children is high, and more women may delay having children because of work and study. |
| Death rates | Death rates may be higher where healthcare, clean water and nutrition are weaker. However, death rates can fall quickly when health services improve. | Death rates are often lower because of better healthcare, sanitation, nutrition and living conditions. In ageing countries, death rates may rise slightly as the population becomes older. |
| Net migration | Some LEDCs may lose workers through emigration if people leave to find better jobs and higher wages abroad. | Some MEDCs may gain population through immigration because they offer more job opportunities, higher incomes and better public services. |
Simple exam point: LEDCs often have faster population growth because birth rates are usually higher. MEDCs often have slower population growth because birth rates are usually lower and many people have children later in life.
3. Effects of changes in the size and structure of population
A change in population affects labour supply, demand for goods and services, government spending and the use of resources.
Optimum population
Optimum population is the population size that gives the highest possible output or standard of living per person, using the country’s available resources.
How to read the graph: as population first rises, GDP per head increases because there are more workers and resources are used more fully. At the optimum point, GDP per head is at its highest. After this point, over-population may occur and GDP per head starts to fall because resources become stretched.
Under-population
Under-population happens when a country has too few people to use its resources fully. More workers could increase output and GDP per head.
Example: a country may have land and minerals but not enough workers to develop them.
Over-population
Over-population happens when there are too many people compared with available resources. This can lower living standards.
Example: too many people may create pressure on housing, schools, hospitals, jobs and clean water.
Population distribution and structure
Population structure describes how a population is made up. Two important parts are age distribution and gender distribution.
| Type of population structure | What it shows | Why it matters |
|---|---|---|
| Age distribution | The share of young people, working-age people and elderly people in the population. | A young population increases demand for schools. An ageing population increases demand for healthcare and pensions. |
| Gender distribution | The number or percentage of males and females in the population. | It can affect labour supply, family structure and demand for different goods and services. |
| Geographical distribution | Where people live within a country, such as cities, towns or rural areas. | A high urban population can increase pressure on housing, transport and public services in cities. |
4. Effects on different countries
Fast-growing population
- Can increase the future labour force.
- Can increase demand for goods and services.
- Can put pressure on schools, hospitals, housing and jobs.
Ageing population
- May reduce the size of the workforce.
- Can increase spending on pensions and healthcare.
- May require people to work for longer before retirement.
Working-age population
- Can raise output if enough jobs exist.
- Can increase tax revenue for the government.
- Can cause unemployment if job creation is too slow.
Quick revision summary
- Population is the total number of people in an area.
- Population growth depends on births, deaths and net migration.
- LEDCs often have higher birth rates, while MEDCs often have lower birth rates.
- Optimum population gives the highest output or living standard per person.
- Population structure includes age distribution and gender distribution.
Easy exam method
When answering population questions, use this simple flow:
- Define the key term.
- Identify whether the question is about birth rate, death rate, migration or population structure.
- Explain one effect on workers, output, public services or living standards.
- Give a simple example such as pressure on schools, hospitals, jobs or pensions.