Human Population Dynamics and Structure

Population density = total population ÷ area = 18 000 000 ÷ 300 000 = 60 people per km².

The dependency ratio is the number of dependants (people aged 0-14 and 65+) compared with the working-age population, expressed as dependants per 100 working-age people.

The working-age population is usually taken as those aged 15-64.

Dependants = 9 + 1 = 10 million (aged 0-14 plus aged 65+).

Working-age population = 20 million (aged 15-64).

Dependency ratio = (10 ÷ 20) × 100 = 50.

Meaning: there are 50 dependants for every 100 working-age people, so the working population supports a relatively low number of dependants — a comparatively light burden. Most of the dependants here are children (a youthful population), so there will be future pressure on schools and, later, on jobs.

Environmental factor — relief and climate. Flat, fertile land with a reliable water supply and a mild climate supports farming and settlement, so density is high; mountains, deserts and very cold regions are hard to live in, so density is low.

Economic factor — jobs and resources. Areas with industry, trade and resources offer employment, attracting people and raising density; remote areas with few jobs have low density.

Social/political factor — services and stability. Good services (schools, hospitals, transport) and a stable government attract people and raise density, while conflict or poor services lead to low density (and emigration).

Comparison (AO2). The LIC pyramid (Fig. 1) has a much wider base, showing a large proportion of children (0-14) and therefore a high birth rate; it narrows steeply, so there are few elderly people, indicating a lower life expectancy. The HIC pyramid (Fig. 2) has a narrow base (few children, low birth rate) and straighter sides with a broad top, showing a high proportion of elderly people and a long life expectancy. Overall the LIC population is youthful and expanding, while the HIC population is ageing.

Suggested reasons (AO3).

• The LIC's high birth rate may be due to limited access to contraception, children being needed for farm labour and to support parents in old age, lower education (especially of women), and cultural factors. Higher infant mortality also encourages larger families.
• The HIC's low birth rate reflects widespread contraception, education and careers for women, the high cost of raising children, and low child mortality, so fewer children are "needed".
• The HIC's broad top reflects low death rates and long life expectancy from good health care, nutrition and sanitation.

Overall: as countries develop, they tend to move from the youthful LIC pattern towards the ageing HIC pattern.

Introduction. A larger population clearly needs more food, water, energy and land, so population size matters for environmental impact. But it is not the only factor — how much each person consumes, and the technology used, may matter just as much. This essay weighs population size against these other influences before reaching a judgement, using the idea that total impact depends on population × consumption per person × technology.

The case that population size is the most important factor.

• More people means greater total demand for resources — more food production (clearing land, using water and fertiliser), more housing, more energy and more waste.
• Rapidly growing populations, often in LICs, can place severe pressure on local environments: deforestation for fuelwood and farmland, overuse of water, and soil degradation.
• A larger population also produces more pollution overall, all else being equal.

The case that other factors matter more.

• Consumption per person can outweigh sheer numbers. A typical citizen of a high-income country uses far more energy and resources and emits far more carbon dioxide than a citizen of a low-income country, so a small, wealthy population can have a larger total footprint than a large, poor one.
• Technology and management change impact dramatically: clean energy, efficient farming and good environmental laws can reduce the impact of a large population, while wasteful technology magnifies a small one.
• Distribution and lifestyle matter too — dense, well-planned cities can be more efficient per person than sprawling settlement.

Judgement. The most useful way to judge is by total impact = population × consumption per person × technology. By this criterion, population size is a major factor but not automatically the most important one: where consumption per person is very high, that factor can dominate; where a large population consumes little, its per-person impact is small. The greatest environmental damage occurs when a large population also consumes heavily and uses polluting technology. The statement is therefore an overstatement — population size matters, but it is one of three interacting factors, and in high-income contexts consumption per person is often the more decisive driver. Effective environmental management must address all three, not population size alone.