What is population ageing?
Population ageing means the share of older people (usually 65 and above, sometimes 60 and above) in a population keeps rising. It is not only that people are living longer; it is that older people become a bigger part of the whole.
Demographers use a common ladder. A society is ageing when 7% or more are 65+, aged at 14%, and super-aged at 20%. The median age (the age that splits the population into two equal halves) also rises.
Birth and death are not only personal events. How many children a society has and how long people live shape its schools, jobs, cities and care for the old. That is why demography matters for the future.
Causes: low birth rate and longer lives
Two things drive ageing together.
1. A low birth rate. The total fertility rate (TFR) is the average number of children a woman has in her life. About 2.1 keeps a population steady (the replacement level); anything lower makes each generation smaller. Common reasons for lower TFR:
- girls and boys study longer, so adult life and marriage start later,
- women work in more jobs, and work and family are hard to combine,
- housing, school and child-care costs are high, especially in cities,
- family planning is available and smaller families become the norm,
- worry about jobs and the future.
2. Longer life. Clean water, vaccines, medicines, better food and safer childbirth lower death at every age, so life expectancy rises. Fewer babies at the bottom and more survivors at the top make the pyramid top-heavy.
Some countries, such as South Korea (TFR below 1) and Japan, are far ahead on this path. Many others are following.
Effects on society and the economy
The old-age dependency ratio = (people 65+) ÷ (people 15–64) × 100. It shows how many older people each 100 working-age people may support. When it rises, pressure grows.
- Labour supply: fewer young workers; some jobs go unfilled; businesses use more machines.
- Public money: pensions and health care cost more while fewer people pay taxes.
- Education: fewer children, so schools and colleges may close or merge.
- Regions: young people leave villages, which then age even faster.
- Families: smaller families have fewer people to care for grandparents; loneliness among the old can grow.
There are positives: older people bring experience, many stay active and work longer, and a "silver economy" of health, travel and care services grows. Old age can be lived with independence and good health (wellbeing) if the society plans for it.
Responses: what societies do
No single fix works. Countries combine several:
- Support families: child-care, parental leave for both parents, affordable housing and school costs.
- Keep older people working if they wish: a later and flexible retirement age, part-time work, training for new skills.
- Reform pensions and health care so they stay affordable, with savings schemes and community care.
- Use technology: automation and AI to raise output per worker; health technology for care at home.
- Welcome workers from other countries (immigration), which also makes the society more multicultural and needs good integration.
- Lifelong learning so that people can change jobs at any age.
Notice that more babies help only after about 20 years, so societies need quick measures (later retirement, immigration, technology) and slow ones (family support) at the same time.
Examples: India and the world
Japan: nearly three in ten people are 65 or older, one of the highest shares in the world. South Korea: TFR has fallen below 1, among the lowest ever recorded. Italy and many European countries also have low TFR.
India is still a young country, with a median age in the late twenties and a TFR of about 2, near replacement. But as life expectancy rises, the share of people aged 60+ is projected to roughly double by around 2050. India therefore has a window of time, a large working-age group, to build health care, pensions and skills before ageing speeds up. This window is called the demographic dividend.
Try it
Ask three adults in your family how many brothers and sisters they had and how many children they have. Compare with your own generation. Then count the age groups in your extended family and draw a small bar stack like the 3D model: is the base of your family wider or narrower than your grandparents' family?
Key formulas and definitions
- Total fertility rate (TFR) = average children per woman; replacement level ≈ 2.1
- Old-age dependency ratio = (people 65+) ÷ (people 15–64) × 100
- Workers per older person = (people 15–64) ÷ (people 65+)
- Ageing society: 65+ ≥ 7%; aged: ≥ 14%; super-aged: ≥ 20%
- Median age = the age that splits a population into two equal halves
Worked examples
1. A country has 15 million people aged 65+ and 60 million aged 15–64. Find the old-age dependency ratio.
15 ÷ 60 × 100 = 25. So there are 25 older people for every 100 working-age people.
2. In the same country, how many workers are there for each older person?
60 ÷ 15 = 4 workers for each older person.
3. 12% of a country is aged 65 or over. Is it an "ageing", "aged" or "super-aged" society?
12% is above 7% but below 14%, so it is an ageing society (not yet aged).
4. A country has TFR 1.2. About what fraction of the replacement size does each new generation have?
Roughly 1.2 ÷ 2.1 ≈ 0.57, so each generation is only about 57% (a little over half) of the previous one, ignoring migration.
5. A town of 100 workers and 50 older people raises the retirement age by 4 years. Each year keeps 2 older people working. Find the new workers per older person.
Workers = 100 + 2 × 4 = 108. Older people = 50 − 8 = 42. Ratio = 108 ÷ 42 ≈ 2.6.
6. A school had 600 pupils. The number of children in the area falls by one third. How many pupils remain?
One third of 600 is 200. 600 − 200 = 400 pupils.
Common mistakes
- Saying "the population is ageing" just because it is growing. Ageing means the SHARE of older people rises, even if the total population is rising.
- Mixing TFR with the birth rate. TFR is children per woman; the crude birth rate is births per 1,000 people.
- Thinking more babies fixes the problem fast. They join the workforce only after about 20 years.
- Treating older people only as a burden. Many work, volunteer and care for grandchildren.