NCERT Solutions for Class 8 Social Science Chapter 13 Dynamics of Population (PDF) – 2027

Demography is the study of the composition of a human population — its age, sex, education, occupation, religion and so on — and of how it changes over time through births, deaths and the movement of people.

It has three components (Fig. 6.2): size (how many people), structure and composition (how they are made up by age, gender, education) and pattern and trend (how the numbers are changing). Governments use it to plan schools, hospitals, roads, housing and services; businesses use it to understand their customers.

The four key indicators of demography (Fig. 6.7):

• Birth rate — the number of live births per 1,000 people in a year.
• Fertility rate — the average number of children a woman would have in her lifetime; 2.1 is the replacement level.
• Death (mortality) rate — the number of deaths per 1,000 people in a year.
• Migration — the movement of people from one place to another, within or outside the country.

Other important concepts: census, life expectancy, sex ratio, population pyramid, demographic transition and demographic dividend.

Both have grown enormously, but growth is now slowing down.

• World: 2.5 billion (1950) → 8.2 billion (2025). It is expected to reach 9.7 billion by 2050, peak at about 10.3 billion in the mid-2080s and then slowly decline (Fig. 6.4).
• India: 361 million (1951) → about 1,460 million (2025), about four times (Fig. 6.5). In 2023 India passed China as the most populous country; Indians are about 17 per cent of the world’s people.
• Why: after 1950 better healthcare made death rates fall while birth rates stayed high; now birth rates are falling too. China, Japan and Italy are already shrinking, while Nigeria and Ethiopia still grow rapidly.

Population trends decide what a society needs, who does the work and who pays for services.

• A young population (India: nearly 65 per cent aged 15–59, median age 28) can work, earn and pay taxes — the demographic dividend — if it gets good education, skills, healthcare and jobs.
• An ageing population (Japan, China) means fewer workers, slower economic growth, more need for healthcare and difficulty paying pensions.
• Migration makes cities such as Delhi, Mumbai and Bengaluru grow, putting pressure on water, land, transport and housing.
• Smaller families change society: China’s One-Child Policy left a generation without siblings.

About 8.2 billion people lived in the world in 2025 (Fig. 6.6). There were 2.5 billion in 1950, and the number is expected to reach 9.7 billion by 2050. Asia has the most people (4.8 billion, about 59 per cent), followed by Africa (1.5 billion). India alone has about 144 crore people — roughly 17 per cent of the world.

My grandmother says the fields behind our lane have become apartment blocks, the road is now jammed with buses, cars and two-wheelers, and families live in small flats instead of big joint-family houses.

Possible reasons:

• Population growth — India grew from 361 million (1951) to about 1,460 million (2025), so more homes are needed on the same land.
• Migration to towns and cities for jobs and education crowds the streets and transport.
• Smaller families — fertility fell from 5.7 to 1.9, and city living is costly, so people choose smaller homes.
• Rising incomes let more families buy vehicles.

Because not every child who is born survives to grow up and become a parent. Some children die before adulthood, and slightly more boys than girls are born. So if every couple had exactly 2 children, the next generation would be a little smaller than the parents’. About one-tenth of a child more per woman makes up for this — hence 2.1.

The replacement rate is higher where more children and young people die before they have children of their own — because of poor healthcare, unsafe water, malnutrition or diseases like malaria and diarrhoea — or where many more boys than girls are born.

Yes. There is an inverse relationship: where more women are literate, the fertility rate is lower.

Sample report — observations:

• Bihar has the lowest female literacy (55%) and the highest fertility (3.0); Delhi has the highest literacy (83.7%) and the lowest fertility (1.6, equal with Punjab).
• Bihar, Jharkhand and Uttar Pradesh (female literacy below 70%) are above the replacement level of 2.1; Karnataka, Punjab and Delhi (above 70%) are below it.
• Jharkhand is a small exception: lower literacy than Uttar Pradesh, but slightly lower fertility.

Possible reasons: educated girls marry later and have fewer children; more educated women work in formal jobs; city living is costly, so families stay small; and educated mothers use health services, so more of their children survive.

The village would lose many of its working-age people and be left mostly with children and elderly people. Possible changes:

• Fewer workers for farming — some land may be left uncultivated, and farm wages may rise.
• Money sent home by migrants can pay for better houses, schooling and healthcare.
• Elderly parents may be left alone, with less care.
• Fewer children over time, so village schools may have to be merged or closed.
• Returning migrants may bring back new skills and ideas.

Possible reasons why Kerala, Puducherry and Tamil Nadu have a sex ratio near or above 1,000:

• Better healthcare and nutrition for women. When women get the same care as men, they usually live longer than men.
• Daughters are valued, so girls get equal food and medical care and fewer die in childhood.
• High female literacy — educated mothers use health services, so girls survive.
• More elderly people — Kerala has the highest share of elderly (12.6%, Fig. 6.19), and older age groups have more women.
• Men migrate out for work (for example from Kerala), so more women than men are counted at home.

The pyramid would lose its wide base. Each new generation of children would be smaller than their parents’ generation, so the bottom bars become narrower than the middle — the shape turns into a bell and then an upside-down “urn”, widest in the middle and upper ages.

Yes. In time the number of children can become smaller than the number of aged people. Japan is already like this, and Fig. 6.18 shows India’s 65+ group overtaking its 0–14 group around 2050.

Such a population keeps growing for a while, then stops, then shrinks and grows older. There are fewer workers, more elderly people needing healthcare and pensions, and slower economic growth — as in Japan and China.

Older people contribute in many ways even after they stop earning:

• looking after grandchildren so that the parents can go to work;
• sharing knowledge not found in books — farming, home remedies, recipes, family and local history;
• teaching crafts, music and other skills to the young;
• guiding rituals and festivals and telling stories, which keeps culture alive;
• settling disputes and helping to run community groups;
• many keep working — running a shop, farming, tutoring.

Sample answer: In our lane an elderly aunt looks after three small children while their mothers go to work, and a retired postman teaches mathematics to children free of cost every evening.

Studying its population helps a country plan for its people and use its resources well.

• Many young children → more schools are needed.
• More elderly people → more healthcare facilities are needed.
• A large working-age population → more jobs must be created.
• It helps plan roads, housing, water, energy and waste management.
• Businesses use it to know their customers by age, gender and income.

In India this information is collected through the census, generally every 10 years.

A low fertility rate means fewer children now, and so fewer workers in the future.

• After about 20 years fewer young people join the workforce, so farms, factories and offices face a shortage of workers.
• As more people grow old and retire, economic growth can slow down.
• The government gets fewer young taxpayers but must pay more pensions and healthcare costs.

Example: China’s fertility rate fell from 7.5 (1963) to 1 (2025). Its population peaked at 1.43 billion in 2022, and its share of people over 65 is expected to rise from 14% (2023) to 26% (2050).

No, a high birth rate is not always good.

• It can help if the children are educated, kept healthy and later find jobs — they become a large workforce (a demographic dividend), as India has today.
• It can harm if the country cannot provide enough food, schools, healthcare, housing and jobs — it then leads to shortages, unemployment and overcrowded cities. China feared exactly this in the 1970s.

So what matters is whether the country invests in its people. A very low birth rate also causes problems — an ageing, shrinking workforce.

Neither is always better. What matters is the age structure and whether the country can educate, keep healthy and employ its people.

Fast-growing population: shortages of food, jobs and housing; schools and hospitals must be built quickly; crowded cities strain water, land, transport and housing.

Shrinking population: fewer young workers and slower economic growth; more elderly people needing healthcare; pensions hard to pay with fewer taxpayers (for example Japan and China).

My view: a country does best when its population grows at a pace its schools, hospitals and job market can keep up with.

The age structure decides which services are needed and what kind of workforce is available.

• Many children (about 27% of Indians are under 15): schools, anganwadis, vaccination and child healthcare — and jobs for teachers and nurses.
• Many working-age people (nearly 65% of Indians are 15–59): jobs above all, and colleges, skill training, transport and housing.
• Many elderly people (Japan, median age 50; Kerala, 12.6% elderly): hospitals, care workers and pensions. Japan has raised its retirement age and uses robots and AI assistants to help care for older people.

Why families are getting smaller: more girls are educated and marry later; more women work in formal jobs; city living is costly; and because fewer children die young, parents do not need many births. India’s fertility rate fell from 5.7 (1950) to 1.9 (2025).

Does it ensure better education and health? No, it does not ensure it, but it makes it more likely, because the family’s money and time are shared among fewer children. Good schools, health centres and equal care for daughters are also needed.

Effects: more nuclear families and smaller homes; fewer siblings and relatives; more elderly people supported by fewer young people; and, in future, an ageing population.

a) Yes. Life expectancy at birth rose from about 43 years (males) and 41 years (females) in 1950 to about 65 and 69 years in 2010, and it is projected to keep rising. Reasons: better healthcare — antibiotics, vaccines, oral rehydration solution; safe water and sanitation; fewer child deaths from malaria and diarrhoea (child mortality fell from 271 to 28 per 1,000); better nutrition and rising incomes.

b) In 2010: males about 65 years, females about 69 years — women could expect to live about 3–4 years longer.

A demographic dividend is the economic growth potential a country gets when a large part of its population is young and of working age.

How it benefits: more people work in farms, factories, offices and businesses, so production rises; workers earn and pay taxes that build schools, hospitals and roads; and each worker has fewer dependants to support.

What India should do before 2050 (after which its population starts to age):

• provide good education and skill training;
• improve healthcare and nutrition;
• create enough jobs;
• provide childcare and flexible work so that more women can join the workforce.

Sample answer — India and Japan (figures from this chapter):

Reasons: Japan’s fertility rate has been far below 2.1 since at least 2000 and its people live long, so its population is old and shrinking. India’s fertility fell only recently, so its population is still young and growing.

How Japan manages ageing: it has raised the retirement age and uses automation, robots, AI assistants and community centres to care for older people.

Questionnaire: Migration in our locality (fill one form for each person; about 20–25 people of different ages and occupations).

Steps: Draw a vertical line in the middle of the graph paper and mark the 17 age groups up it, 0–4 at the bottom and 80+ at the top. Mark the percentages outwards from the centre line on both sides with the same scale (1 cm = 1 per cent): males on the left, females on the right. Draw a horizontal bar for each value, label both axes and add a title.

The base is slightly narrower than the middle: the widest bars are 20–24 (9.5% males, 9.1% females). Births are falling, and the working-age group is large.

Observations:

• It is not a pyramid: the base is the narrowest part (about 0.4 million people per year of age), while the widest bars (about 1 million) are in the middle and upper ages — very few children are being born.
• There are two bulges: people aged about 74–77 (born just after the Second World War) and about 49–54 (their children).
• The top is wide, with more women than men at older ages — women live longer.

Inference: Japan has an ageing, shrinking population (median age 50). Deaths exceed births, the workforce will shrink, and more elderly people will need care and pensions.