Birth rate, death rate & natural change

The size of a population changes through births, deaths and migration. Two rates are measured per 1000 people per year:

• Birth rate — live births per 1000 people per year.
• Death rate — deaths per 1000 people per year.

The natural increase rate is birth rate − death rate. If births exceed deaths the population grows naturally; if deaths exceed births it falls (natural decrease). Migration then adds or removes people on top of this.

Key idea: Over-population = too many people for the resources available (falling living standards). Under-population = too few people to use the resources fully. Governments use anti-natalist policies to slow growth or pro-natalist policies to encourage births.

Your turn — natural increase rate

Your turn — as a percentage

The Demographic Transition Model (DTM)

The DTM shows how birth and death rates, and total population, change as a country develops through stages:

• Stage 1 — High fluctuating: high birth rate and high death rate; population low and stable.
• Stage 2 — Early expanding: death rate falls (better food, water, medicine) while birth rate stays high; population grows fast.
• Stage 3 — Late expanding: birth rate falls (contraception, education, urbanisation); growth slows.
• Stage 4 — Low fluctuating: low birth rate and low death rate; population high and stable.

Some models add a Stage 5 where birth rate drops below death rate and the population begins to decline.

Which stage grows fastest?

Population pyramids & dependency

A population pyramid plots the number (or percentage) of males and females in each age group. Its shape shows a country's structure:

• Wide base — high birth rate, many young people (typical of a less developed country).
• Narrow base, tall top — low birth rate and an ageing population (typical of a more developed country).

The dependent population is the young (0–14) and elderly (65+) who rely on the working-age population (15–64). A high dependency ratio puts pressure on workers, schools, pensions and healthcare.

Dependent or working-age?

Tap a group of people, then tap the category it belongs to.

Why people cluster or spread out

Population density = people per km². Distribution is how people are spread across an area. Factors that make areas densely or sparsely populated:

• Physical: flat, low land, fertile soil, reliable water and a mild climate attract people; mountains, deserts, dense forest and extreme climates repel them.
• Economic: jobs, industry, ports and mineral resources draw people in.
• Social & political: good services, transport links, stable government and investment raise density.

Settlement patterns

The shape a settlement makes on the ground is its pattern:

• Dispersed — buildings scattered widely apart, often in remote farming or upland areas.
• Linear — buildings in a line, following a road, river or valley.
• Nucleated — buildings clustered tightly together, usually around a crossroads, market or water supply.

Name the pattern

Settlement hierarchy & services

Settlements can be ranked in a hierarchy from small hamlets up to large cities. Larger settlements are fewer but serve bigger areas:

• Sphere of influence — the area served by a settlement or shop.
• Threshold population — the minimum number of customers a service needs to survive.
• Low-order services (newsagent, post box) are used often, need a small threshold and are found in villages.
• High-order services (department store, hospital) are used rarely, need a large threshold and are found only in towns and cities, with a large sphere of influence.

Match each term to its meaning

Tap a term on the left, then its matching meaning on the right.

Urban land-use zones

Towns and cities show zones of land use, often in roughly concentric rings:

• CBD (Central Business District) — the centre: shops, offices, high land values, tall buildings, good accessibility.
• Inner city — older, high-density housing and former industry near the centre.
• Suburbs — newer, lower-density residential housing further out.
• Rural–urban fringe — the edge where the city meets the countryside; space for out-of-town retail, industry and new estates.

Where are land values highest?

Urbanisation & squatter settlements

Urbanisation is the growing share of people living in towns and cities. In many lower-income countries it is driven by:

• Rural push factors — poverty, drought, lack of jobs and services in the countryside.
• Urban pull factors — hopes of jobs, higher wages, schools and hospitals.
• High natural increase among young migrants already in the city.

Rapid growth can outpace housing, so squatter (informal) settlements — self-built housing on unused land, often lacking clean water, sanitation and secure land rights — grow on the city edge. Strategies include site-and-service schemes and self-help upgrading.

Case study flag: Cambridge expects a named case study of a rapidly growing city and its squatter settlements. Check any specific figures (population, growth rates) against your class notes before quoting them.

Your turn — population density

Over- or under-populated?

The big ideas to know

You've covered the core of Cambridge Theme 1 — Population & Settlement. Press Finish to see your score.