Exploring Society II · Chapter 6 — Dynamics of Population

Suppose your town council must decide whether to build a new primary school or a new hospital ward for old people. How would it choose? It needs to know who lives in the town: how many children, how many elderly people, how many workers. Studying such facts about people is called demography.

Definition. Demography is the study of the human population: its size, its make-up by age, gender, education, occupation, religion and so on, and how these change over time because of births, deaths and the movement of people. Demographers look at four things:

• Size: how many people there are.
• Structure and composition: how the population is made up by age, gender, education and other features.
• Pattern and trend: how these numbers change over the years.
• Distribution: where people live.

Why it matters. Demography helps governments plan:

Businesses use it too: a company deciding what to sell studies people's age, gender and income to match its products to their needs.

Working-age population. People aged about 15 to 64 are called the working-age population, because they are usually the most productive and form most of the workforce. (Indian data often use 15 to 59.)

The census. In India, a census is generally held every 10 years. It is the official count of everyone living in the country at a particular time, and collects information about each person's age, gender, marital status, education, language, religion, family size, occupation, employment and income. It is the biggest source of demographic facts about the country.

Three forces of change. A population changes in only three ways: people are born, people die, and people move in or out. Every topic in this chapter comes back to these three forces.

India: the most populous country. In 2023 India overtook China to become the most populous country in the world. Today about 17 per cent of all the people on Earth, roughly one in six, are Indians.

The world's growth. The world population rose from 2.5 billion in 1950 to 8.2 billion in 2025, and is expected to reach 9.7 billion by 2050. United Nations projections suggest it will peak at about 10.3 billion in the mid-2080s and then slowly fall as birth rates drop. (A projection is a forecast based on present trends.)

Why so fast after 1950? Mainly because people began to live longer. Antibiotics, vaccines and oral rehydration solution saved millions of lives; clean water and sanitation reached more people; deaths of children from malaria and diarrhoea fell; and economic progress spread to more countries. Fewer deaths with births still high meant rapid growth.

Different countries, different directions. China, Japan and Italy already have shrinking populations. India's is still growing for now. Some African countries, such as Nigeria and Ethiopia, are growing fast.

India's own growth.

India's population has multiplied about four times since 1951. Notice that the jump in each decade grew larger until about 2001, and has been growing more slowly since.

Where the world lives. In 2025, of the 8.2 billion people on Earth, Asia had about 4.8 billion and Africa about 1.5 billion, while Australia and Oceania had under 50 million. More than half of humanity lives in Asia.

Every country's population today is the result of years of births, deaths and migration. Two measures describe births.

Replacement level: 2.1. For a population to stay stable over the long run, each couple needs to be 'replaced' by about two children. The figure used is 2.1, slightly more than 2, because some children die before they grow up and slightly more boys than girls are born. If the fertility rate stays above 2.1, the population tends to grow; if it stays below 2.1, it will eventually shrink. Where many children die young, the replacement level is higher.

China's one-child policy. Worried about shortages of food, jobs and housing, China in 1979 allowed most families only one child, with fines or job loss for those who broke the rule. China's fertility rate fell from 7.5 in 1963 to about 1 in 2025. Its population peaked at 1.43 billion in 2022 and is now shrinking, while the share of people above 65 is expected to rise from 14 per cent (2023) to 26 per cent (2050). A whole generation grew up without brothers, sisters or cousins. China ended the policy in 2015 and now allows three children, but fertility is still below replacement.

India's experience. India promoted small families through campaigns such as 'Hum do, humare do' (we two, our two) from 1952 onwards. India's fertility rate has fallen from 5.7 in 1950 to 1.9 in 2025, now below replacement, though the population is still growing because so many people are young.

Why fertility falls. The biggest factor is education, especially of girls: educated women often work in formal jobs, marry later and have fewer children. City life is costly, so urban families also prefer fewer children. The link with education is clear across Indian states:

As women's literacy rises, the fertility rate generally falls.

Death or mortality rate. The death rate is the number of deaths in a year for every 1,000 people. A low death rate is a sign of good health care and nutrition.

Child mortality. A key measure is child mortality: the number of children who die before the age of five for every 1,000 live births. India has made huge progress here:

Life expectancy is the average number of years a newborn can expect to live if today's health and living conditions stay the same. A life expectancy of 70 does not mean everyone dies at 70; it is an average. Some people live to 95, while some die young, and the average works out to about 70.

Migration. Migration is the movement of people from one place to another, within a country or across borders, to settle for a while or for good. People move for several reasons:

• Pull factors attract people to a place: jobs, better education, health care.
• Push factors drive people away: lack of work, natural disasters such as floods or droughts, conflict or political instability.

Effects on cities. Places that receive many migrants grow quickly. Delhi, Mumbai and Bengaluru have grown largely because of migration. But a very large population in a small area puts pressure on water, air and land, and strains transport and housing. You will study these challenges in the next chapter.

Effects on villages. When many young people leave villages for cities, the village may be left with mostly children and elderly people. Farms may be short of workers, but money sent home by migrants (remittances) can improve houses, schooling and health in the village.

Putting it together. Births add people, deaths remove them, and migration moves them around. A country's population today is the sum of all three over many years.

People pass through childhood, adulthood and old age. Countries, too, pass through stages as their birth and death rates change. Demographers call this the demographic transition. It is driven by economic development, better health care and education, and by women having a greater say in household decisions.

Stage 1: high births, high deaths. Many babies are born, but many people, especially children, die from disease and hunger. The two cancel out, so the population hardly grows.

Stage 2: deaths fall, births stay high. Medicines, vaccines and clean water cut deaths sharply. But families still have many children, as they are used to doing. The gap between births and deaths becomes wide, and the population grows rapidly. Countries in this stage have a 'youth bulge', a large share of young people.

Stage 3: deaths low, births fall. As cities grow, incomes rise, education spreads and more women work, families choose to have fewer children. Births fall towards deaths, and growth slows. If fertility falls very low, births drop below deaths and the population shrinks, as in Italy, Japan and South Korea.

Reading the gap. The secret of the transition is the gap between the birth-rate line and the death-rate line. A wide gap means fast growth; a narrow gap means slow growth; if the birth line falls below the death line, the population declines.

Where India stands. India passed through Stage 2 after independence and is now in Stage 3. Its fertility rate is below replacement, but its population is still growing because the large number of young people born earlier are now having families. Growth will slow further and is expected to stop in the coming decades.

Distribution across states. India's people are spread very unevenly across its states. A handful of states hold a large share of the population.

Just these nine states together hold about 70 per cent of India's people, while many states in the Himalayas and the north-east each have less than 1 per cent. Uttar Pradesh alone has about one in six Indians.

Population composition. Besides where people live, demographers study the population's features such as age, gender, occupation and education. This is called the structure or composition of the population.

Sex ratio. One key measure is the sex ratio: the number of females for every 1,000 males. It shows the balance between women and men, and it also reflects a society's social, economic and cultural conditions, such as whether girls get the same nutrition and health care as boys.

In 2011 women made up 48.5 per cent of India's population. The ratio has improved, but it is still below 1,000, which means there are fewer women than men. A few states and union territories, such as Kerala, Puducherry and Tamil Nadu, have had sex ratios at or above 1,000. Better education and health care for women, and fewer harmful practices against girls, are among the likely reasons.

Why a balanced sex ratio matters. A balanced ratio supports fair development, social stability and healthy population growth. A low ratio can signal that girls are neglected or discriminated against, which is why campaigns to value and educate girls matter.

How can you see a country's whole age structure in one picture? With a population pyramid (also called a population structure diagram). It is a special bar graph: each bar is an age group, with males on one side and females on the other. Young age groups are at the bottom and old ones at the top.

Reading the shape.

Despite the name, the drawing is really a two-dimensional outline whose sides bulge or shrink, so it does not always look like a pyramid.

How India's pyramid has changed.

• 1950s: a narrow triangle with a wide base. Families had many children, and life expectancy was only about 30 to 35 years, so few people reached old age.
• Today: more bell-shaped. The base has narrowed because families have fewer children; the middle, the people aged roughly 15 to 60, has widened a lot.
• Coming decades: the top is slowly widening as people live longer with better health care and nutrition. India will gradually age, as Japan and China already are.

Reading real data. In India's estimated 2021 data, about 8.6 per cent of males and 8.2 per cent of females were aged 0–4, while the largest groups were 15–19 and 20–24 (around 9 to 9.5 per cent each). Only about 0.9 per cent of males and 1.2 per cent of females were 80 or older. The bars are widest just above the base, a sign that births have begun to fall.

Notice the top. At older ages, the female bars are often a little longer than the male bars, because women in India, as in most countries, tend to live slightly longer than men.

Think about it. If a country's fertility stays well below replacement for many years, its pyramid becomes top-heavy: there may be more grandparents than grandchildren.

A young nation. About 27 per cent of Indians are under 15, and nearly 65 per cent are of working age (15–59). India's median age, the age that splits the population into two equal halves, is only 28.

A large young population, especially aged about 16 to 30, is called a youth bulge. It is typical of countries passing from Stage 2 to Stage 3 of the demographic transition.

The demographic dividend. When most people are of working age, more people can work in farms, factories and offices or start businesses. More work means more goods and services, more income and more taxes, which the government can spend on schools, hospitals and roads. This growth potential from a young, productive population is the demographic dividend.

A limited window. This advantage will not last forever. The number of Indian children under five peaked in 2007 and those under 15 in 2011; both are now falling. After about 2050 the young working population will shrink and India will begin to age. Kerala and Tamil Nadu are already ageing faster than Bihar and Uttar Pradesh.

Challenges of ageing. An ageing society has more elderly people needing care and fewer young workers. This strains health systems, slows the economy as workers retire, and makes it harder to pay pensions (regular payments to retired people) with fewer young taxpayers.

How countries respond.

• Developed countries such as Japan have raised the retirement age and use automation, robots and AI assistants to fill labour gaps and care for the elderly.
• Developing countries such as India must turn the dividend into real progress through good education, skills training and health care.
• Supporting women's work. Women in jobs often face a 'double burden' of work and housework. Childcare centres, flexible hours and family support help more women join the workforce.

The elderly as a resource. The old Indian idea of āshrama dharma divides life into four stages. Older people may step back from earning, yet they pass on wisdom, skills, stories and traditions. A wise society values their role.

The lesson. India's young population is a great opportunity, but only if young people are healthy, educated and employed. The time to invest is now, before 2050.