Big picture
The world's population passed 8 billion in 2022. But people are very unevenly spread: some regions are crowded, while others are almost empty. Population also changes over time through births, deaths and migration.
This chapter explains where people live and why, how populations grow, and how the demographic transition describes the way populations change as societies develop.
Learning goals
Describe patterns of world population distribution and density.
Explain the geographical, economic, social and cultural factors affecting distribution.
Explain the components of population change and calculate growth rates.
Explain migration and its push and pull factors.
Describe trends in world population growth and doubling time.
Explain the demographic transition theory and population control measures.
Core ideas
1. Distribution of population
Distribution refers to the pattern of where people live.
About 90% of the world's population lives on about 10% of its land area.
The ten most populous countries together hold about 60% of the world's people, and Asia alone holds about 60%.
Densely populated regions include East Asia, South Asia, Southeast Asia, Europe and north-eastern USA. Sparsely populated regions include the polar regions, hot and cold deserts, high mountains and dense equatorial forests.
2. Density of population
Density of population = Population ÷ Area (persons per square kilometre).
Example. A region of 2,000 sq km has 5,00,000 people. Density = 5,00,000 ÷ 2,000 = 250 persons per sq km.
3. Factors affecting distribution
Type | Factor | Effect |
|---|---|---|
Geographical | Availability of water | People prefer areas with fresh water; river valleys (Ganga, Nile) are densely populated |
Landforms | Flat plains and gentle slopes attract people; mountains and hills are sparsely populated | |
Climate | Moderate climates attract people; very hot, cold or wet areas have fewer people | |
Soils | Fertile soils (alluvial, loamy) support agriculture and dense population | |
Economic | Minerals | Mineral-rich areas attract miners and industries (Katanga–Zambia copper belt) |
Urbanisation | Cities offer jobs, education, health care and amenities | |
Industrialisation | Industrial belts provide employment (Kobe–Osaka region of Japan) | |
Social and cultural | Religious and cultural significance; peace and stability | Holy places attract settlement; conflict and insecurity drive people away |
4. Components of population change
Crude birth rate (CBR): number of live births in a year per 1,000 people.
Crude death rate (CDR): number of deaths in a year per 1,000 people.
Natural growth = Births − Deaths. Actual growth = Births − Deaths + In-migration − Out-migration.
Positive growth: births exceed deaths, or in-migration adds to population. Negative growth: population falls, as in some European countries with low birth rates.
Example. CBR = 25 per 1,000 and CDR = 10 per 1,000. Natural growth rate = 25 − 10 = 15 per 1,000 = 1.5% per year.
5. Migration
Migration is the movement of people from one place to another. The place people leave is the place of origin; the place they move to is the place of destination.
Emigrants leave a place; immigrants arrive in a new place.
Migration may be permanent, temporary or seasonal, and internal or international.
Push factors (make people leave) | Pull factors (attract people) |
|---|---|
Unemployment, poor living conditions | Better job opportunities |
Political turmoil, war, insecurity | Peace and stability |
Unpleasant climate, natural disasters, epidemics | Pleasant climate |
Socio-economic backwardness | Security of life and property, better amenities |
6. Trends in world population growth
For most of human history, population grew very slowly, because high birth rates were balanced by high death rates.
After the Industrial Revolution (about 1750), and with improvements in agriculture, medicine, sanitation and transport, death rates fell while birth rates stayed high, causing rapid growth.
The world reached 1 billion around the early nineteenth century, and has grown much faster since: it took over a century to reach 2 billion, but only about a decade or so to add each recent billion. It passed 8 billion in 2022.
Doubling time is the time a population takes to double at its current growth rate. A useful approximation is the rule of 70: doubling time ≈ 70 ÷ growth rate (%). At 1.5% per year, a population doubles in about 70 ÷ 1.5 ≈ 47 years.
7. Demographic transition theory
The demographic transition theory describes how a population changes from high births and high deaths to low births and low deaths as a society moves from rural, agrarian and illiterate to urban, industrial and literate.
Stage | Birth rate | Death rate | Population growth | Features |
|---|---|---|---|---|
Stage 1 | High | High (fluctuating) | Slow | Agriculture-based economy; large families; poor health care; low life expectancy; illiteracy |
Stage 2 | High (declines slowly later) | Falls rapidly | Rapid (population explosion) | Improved health, sanitation and food supply reduce deaths, but birth rates stay high |
Stage 3 | Low | Low | Slow or stable | Urban, industrial, literate societies; family planning; small families |
Many developed countries are in Stage 3; many developing countries are in Stage 2 or moving towards Stage 3. Some countries now have birth rates below death rates and face declining and ageing populations.
8. Population control
Thomas Malthus (1798) argued that population grows faster than food supply, which would lead to famine, disease and war (positive checks) unless people practised restraint.
Population control measures: family planning and access to contraception, education (especially of women), better health care (which reduces infant mortality and the desire for many children), raising the age at marriage, and economic development.
A reliable approach to questions
For distribution, describe crowded and sparse regions and explain them with factors.
Calculate density, natural growth and doubling time with the formulas.
For migration, give push and pull factors.
For demographic transition, describe the three stages with birth rate, death rate and features.
Connections that matter
India: population applies these ideas to India.
Human development relates population to well-being.
Economics: statistics helps interpret population data.
Common mistakes
Expressing CBR and CDR per 100. They are per 1,000 people.
Confusing natural growth (births − deaths) with actual growth (which includes migration).
Saying population grows fastest in Stage 1. Rapid growth occurs in Stage 2.
Saying people are evenly spread across the world.
Revision checklist
I can describe world population distribution and density.
I can explain factors affecting distribution.
I can calculate density, growth rate and doubling time.
I can explain migration with push and pull factors.
I can explain the demographic transition theory.