How population changes
A country's population changes through the birth rate, the death rate and net migration. The birth rate is births per 1000 people per year; the death rate is deaths per 1000 people per year. When the birth rate is above the death rate there is a natural increase. Net migration adds immigrants and subtracts emigrants.
Key idea
Population change = (births − deaths) + net migration. A falling death rate with a still-high birth rate causes rapid population growth.
Age structure
The age distribution shows the balance of young, working-age and elderly people. Many lower-income countries have a young population with high birth rates, giving a high dependency ratio of children to workers. Many higher-income countries face an ageing population as birth rates fall and people live longer, raising the number of elderly dependants.
Example
As healthcare improves, life expectancy rises and the death rate falls. If the birth rate stays high, the population grows quickly and puts pressure on schools, housing and jobs.
Economic effects
Population growth can enlarge the workforce and the market for goods, but if it outpaces income it lowers living standards. An ageing population raises spending on pensions and healthcare and shrinks the share of workers, while a young population needs heavy spending on education. Managing these pressures is a key development challenge.
Remember
- Change comes from births, deaths and migration.
- Dependency ratio compares dependants with workers.
- Ageing raises pension and health costs.