Human populations

The number of live births per 1,000 people per year.

Births, deaths, and migration.

A high birth rate (large proportion of young people).

High life expectancy and an ageing population.

The number of deaths per 1,000 people per year.

Natural increase (the change due to births minus deaths, excluding migration).

(CBR − CDR) ÷ 10 = annual % change (excluding migration).

A pyramid with a wide base and narrow top, showing high birth rates and rapid population growth (common in LICs).

How long it would take for a population to double at its current growth rate.

The average number of children a woman would have over her reproductive lifetime; replacement level is about 2.1.

Likely continued rapid growth due to a large cohort entering reproductive age.

A pyramid with a narrow base and wider middle/top, showing low birth rates and slow growth or decline (common in HICs).

The ratio of dependents (under 15 and over 65) to the working-age population (15–64). A high ratio increases economic pressure on workers and services.

Doubling time (years) = 70 ÷ growth rate (%).

State the trend (up/down), the rate of change, and any regional differences.

Improved healthcare (vaccinations/medicines) and improved sanitation (clean water/sewage).

Death rate typically falls first due to improved healthcare and sanitation (Stage 2).

A model showing how birth and death rates change as a country develops economically, typically moving from high rates to low rates.

Death rate falls rapidly due to improved sanitation/healthcare while birth rate stays high, causing rapid population growth.

A large gap between high birth rates and rapidly falling death rates.

Female education (girls staying in school tends to delay childbirth and reduce family size).

Increased female education and access to contraception (also urbanisation and employment).

Birth rate falls due to education, urbanisation, and contraception, so population growth slows.

Children become an economic cost rather than an asset; access to education and healthcare increases; women have more employment opportunities.

Better food security reduces malnutrition and increases resistance to disease, lowering mortality (especially infant mortality).

Low birth and death rates with a stable population (typical of many HICs).

It delays marriage/childbearing, increases career opportunities, improves knowledge and use of family planning, and changes desired family size.

Healthcare/sanitation mainly reduce CDR; female education/contraception mainly reduce CBR.

Not all countries follow the same pathway; very low birth rates and ageing can cause decline, but policies/migration can alter trends.

Look at whether CDR is falling, whether CBR is falling, and the size of the gap between them (growth rate).

A strategy that provides contraception, information, and services so people can choose family size without coercion.

Impact (I) = Population (P) × Affluence (A) × Technology (T).

I = P × A × T; it is used to explain how population, consumption, and technology combine to determine environmental impact.

It reduces fertility by delaying childbirth, increasing opportunities, and improving access to family planning.

Consumption per person (how much each person uses).

Food demand (land conversion), water demand (water stress), and energy demand (emissions and climate change).

Female education and voluntary family planning.

It increases demand for food, water, and energy, which can drive land conversion, pollution, and resource depletion.

They violate reproductive rights and can lead to discrimination and abuse (e.g., forced sterilisation, gender imbalance).

Policies that encourage births (e.g., childcare support or tax benefits) used in countries with ageing/declining populations.

Higher affluence means much higher per-capita consumption and emissions, raising total impact even with fewer people.

Because high-consumption lifestyles can create very large impacts even with small populations, while large low-consumption populations may have lower per-capita impacts.

A balanced judgement that weighs effectiveness, ethics, and evidence, and clearly justifies the recommended approach.

Population size and consumption patterns (affluence), not just total numbers.

Discuss effectiveness and unintended consequences, then evaluate ethical implications (rights, equity, who decides), and conclude with a justified judgement.