Demographic transition theory

Detail

What the theory says

• Demographic transition theory: a theory that describes a region's population today and predicts its future.
• It links population change to the kind of society people live in.
• A society changes from rural, agrarian (farming) and illiterate to urban, industrial and literate.

• As this happens, the population moves from high births and high deaths to low births and low deaths.

• Demographic cycle: the name for all these stages taken together (NCERT Fig. 2.2).

• Key terms:
• Fertility: births. It is measured by the birth rate, which is births per 1,000 people per year.
• Mortality: deaths. It is measured by the death rate, which is deaths per 1,000 people per year.
• Natural growth: birth rate minus death rate. The gap between the two lines in Fig. 2.2 shows how fast the population grows.

The three stages (NCERT model)

Stage	Births (fertility)	Deaths (mortality)	Growth	Society
First stage	High	High	Slow	Farming, illiterate, low technology
Second stage	High at first, then falls	Falls	Highest (population explosion)	Sanitation and health care improve
Third stage	Low	Low	Stable or slow	Urban, literate, skilled

First stage of demographic transition

• First stage of demographic transition: births and deaths are both high, so the population grows slowly.
• Why deaths are high:
• Epidemics (diseases that spread to many people at once) kill many people.
• The food supply is uncertain. A bad harvest can mean famine.

• As a result, life expectancy is low. Life expectancy is the average number of years a person is expected to live.

• Why births are high:

• Parents have many children to make up for the children who die.

• Most people are farmers. For farmers, a large family means more hands to work the land, so it is an asset.

• Other features: illiteracy and low levels of technology.

• All countries of the world were in this stage about 200 years ago.

Second stage of demographic transition

• Second stage of demographic transition: deaths fall quickly, but births stay high and fall only later.
• How the population explosion happens:
• Sanitation and health care improve, so the death rate falls.
• The birth rate stays high at first, because old family habits change slowly.
• Births and deaths are now far apart, so a lot of people are added every year.

• This fast growth is called the population explosion.

• Later in this stage the birth rate also starts to fall, and the gap begins to close.

Third stage of demographic transition

• Third stage of demographic transition: births and deaths are both low.
• The population becomes stable or grows slowly.
• People live in towns and cities, are literate and have technical skills.
• They choose to have small families.

The lesson

• People are flexible. They change how many children they have when conditions change.
• Different countries are at different stages of the cycle today.

Origins of the theory

• Warren Thompson (1929) was an American demographer, meaning a person who studies population.
• He grouped countries by their birth and death rates.

• His grouping was based on about 200 years of change in industrial societies.

• Frank Notestein (1945) turned these observations into a formal theory and named the stages of "transition".

• Thomas Malthus (1798) came much earlier and gave a different view. He said population grows faster than food, so growth is checked by famine, disease and war. Transition theory instead says that growth slows down on its own as societies develop.

The five-stage model (beyond NCERT)

Stage	Name	Births	Deaths	Growth	Examples (indicative)
1	High stationary	High	High	Very slow	No country today; some remote tribal groups
2	Early expanding	High	Falling fast	Very fast	Niger, Chad (early second stage)
3	Late expanding	Falling	Low	Slowing	India, Bangladesh (NCERT: late second stage)
4	Low stationary	Low	Low	Near zero	UK, USA
5	Declining	Below deaths	Low but rising (ageing)	Negative	Japan, Italy, South Korea, China

• Fifth stage (decline): births fall below deaths, so the population shrinks.
• The latest UN figures fit this picture:
• 63 countries and areas, including China, Germany, Japan and Russia, had already reached their highest population by 2024 [2].

• These countries are expected to shrink by about 14% over the next 30 years [2].

• Worldwide, births are falling:

• In 2024, women had on average one child fewer than in 1990 [2].
• In more than half of all countries, fertility is below 2.1 births per woman [2]. This is the replacement level: the number of births needed for each generation to replace itself.

• Nearly one-fifth of countries have "ultra-low" fertility, meaning fewer than 1.4 births per woman (2024) [2].

• At the other end, nine countries are growing so fast that their populations will double between 2024 and 2054 [2]. These are second-stage countries, mostly in sub-Saharan Africa.

Critiques of the theory

• It is based on Europe's experience. It assumes other countries will follow the same path, but they may not.
• Deaths fell faster in today's poor countries.
• Europe's death rate fell slowly over about 150 years, as its own medicine and sanitation improved.
• Asia, Africa and Latin America imported vaccines, antibiotics and DDT after 1945, so their death rates fell within a few decades.

• Their birth rates stayed high, so the gap between births and deaths was wider than Europe's. This made their population explosions bigger.

• Fertility can fall without industrialisation.

• Bangladesh and Kerala (India) saw large falls in fertility while still mostly rural.

• The causes were female literacy, health care and family-planning programmes.

• It cannot predict well when or why the change happens. Culture, religion and government policy also affect fertility.

• It does not explain stage 5. It cannot say how far below replacement level fertility will fall.

What the transition does to age structure

• Age structure: how a population is split between children, working-age adults and old people.
• The transition changes this split, and each stage gives a different shape.

Youth bulge

• Youth bulge: a large share of young people aged 15-24 or 15-29 in the population.
• Where: sub-Saharan Africa, Pakistan, Afghanistan.

• Why: these countries are in late stage 2 or early stage 3. Deaths fell a few decades ago while births stayed high, so a very large group of children has now grown up.

• Two possible results:

• Demographic dividend: extra economic growth when a large working-age group has jobs and few people depend on it.
  • Many workers and fewer dependants mean more savings and more output.
• Unrest: if young people find no jobs, they become frustrated. This can feed protest and conflict, as in debates about the Arab Spring (2010-11).

Population ageing

• Population ageing: the share of old people in a population rises.
• Cause: fewer births mean fewer young people. Fewer deaths mean people live longer.

• Fastest in: Japan, where about 30% of people are 65 or older, followed by Italy and South Korea.

• Global outlook (UN WPP 2024):

• By the late 2070s, people aged 65 and over will outnumber children under 18 [2].
• By the mid-2030s, people aged 80 and over will outnumber infants under 1 [2].

• Global life expectancy was 73.3 years in 2024, up from 70.9 years during the COVID-19 pandemic [2].

• World population path:

• 8.2 billion in 2024 [2].
• Expected to peak at about 10.3 billion in the mid-2080s [2].
• Expected to fall slightly to 10.2 billion by 2100 [2].

Population pyramids

• Population pyramid (age-sex pyramid): a bar graph of a population by age group. Males are shown on the left and females on the right, with the youngest at the bottom.

Shape	What it looks like	Stage	What it means	Example
Expansive	Wide base, narrow top (a triangle)	Stage 2 (early 3)	High births, short lives	Niger, Nigeria, Pakistan
Stationary	Bars of about equal width up to old age (bell or column)	Stage 4	Births and deaths both low and balanced	USA, UK, Australia
Constrictive	Narrow base, wide middle and top	Stages 4-5	Births below replacement; the population is ageing	Japan, Italy, South Korea

• India's pyramid has a base that is getting narrower, with a bulge in the working ages. This shows a country moving from expansive towards stationary, in its demographic dividend window.

Prelims Hooks

• The theory goes back to Warren Thompson (1929) and was made formal by Frank Notestein (1945). It is not Malthus (1798).
• NCERT's three stages: high-high (slow growth) → falling deaths with high births (population explosion) → low-low (stable).
• Highest growth comes in the second stage, not the first. The first stage has high births but slow growth, because deaths are also high.
• About 200 years ago, all countries were in the first stage (NCERT).
• Five-stage model: Niger and Chad are in stage 2; India and Bangladesh are in stage 3 (NCERT: late second stage); UK and USA are in stage 4; Japan is in stage 5 (decline).
• Replacement-level fertility is 2.1. Ultra-low fertility is below 1.4, and nearly one-fifth of countries were there in 2024 [2].
• UN WPP 2024: 65+ will outnumber under-18s by the late 2070s, and 80+ will outnumber infants by the mid-2030s [2].
• World population is expected to peak at about 10.3 billion in the mid-2080s [2]. 63 countries, including China, Japan, Germany and Russia, have already peaked [2].
• Pyramid shapes: expansive = stage 2; constrictive = stages 4-5; stationary = stage 4.
• Trap: Kerala and Bangladesh cut fertility without industrialisation. This weakens the theory's claim that industry must come first.

Mains Points

• Different countries are at different stages, so they need different policies:
• Countries in stage 2 (sub-Saharan Africa) need girls' education, health care and family planning.

• Countries in stages 4-5 (Japan, Italy, South Korea) need pensions, care for old people, automation and immigration.

• Demographic dividend versus youth bulge risk:

• India and South Asia's large young population helps the economy only if they have skills and jobs.

• Without jobs, a youth bulge can lead to unrest, as seen in debates about the Arab Spring.

• Critique for "evaluate" questions:

• The model is based on Europe.
• Imported medicine made the gap between births and deaths wider in poor countries.
• Fertility fell without industrialisation in Kerala and Bangladesh.

• The model has no clear end point once fertility drops far below 2.1, as in the 2024 ultra-low fertility countries [2].

• Ageing changes the world's population pattern:

• 63 countries have already peaked [2], and older people will outnumber children by the late 2070s [2].
• Countries that age fast will depend more on migration from younger countries. This links the demographic transition to world migration flows.