Welcome to Population Geography!
Have you ever wondered why some cities are packed with millions of people while huge areas of land are almost completely empty? Or why some countries have lots of young children, while others have more elderly people? In this chapter, we are going to explore Population—the study of how many people live on Earth, where they live, why they live there, and how population numbers change over time.
Don't worry if demographic terms seem tricky at first. We will break down every single idea step by step with clear formulas, easy analogies, and handy memory tricks!
---1. Key Terms and How Populations Change
Let's start with the basics. Population simply means the total number of people living in a specific geographical area.
Births, Deaths, and Natural Change
To understand whether a population is growing or shrinking, geographers look at two key rates:
- Birth Rate: The number of live births per 1,000 people of the population per year.
- Death Rate (Mortality Rate): The number of deaths per 1,000 people of the population per year.
Watch Out for This Common Mistake: Birth rates and death rates are measured per 1,000 people (\(\text{per } 1{,}000\)), NOT as percentages out of 100!
When we compare the birth rate to the death rate, we get one of two results:
- Natural Increase: Happens when the birth rate is higher than the death rate. More babies are being born than people dying, so the population naturally grows.
Formula: \(\text{Natural Increase} = \text{Birth Rate} - \text{Death Rate}\) - Natural Decrease: Happens when the death rate is higher than the birth rate. More people are dying than babies being born, so the population naturally shrinks.
Formula: \(\text{Natural Decrease} = \text{Death Rate} - \text{Birth Rate}\)
The Complete Population Change Formula
Births and deaths are only part of the story! People also move into and out of countries. This is called migration.
- Immigration: People moving into a country permanently (think: Immi = In).
- Emigration: People leaving or exiting a country permanently (think: Emi = Exit).
To find the total population change, we combine natural change and migration:
\(\text{Population Change} = (\text{Births} - \text{Deaths}) + (\text{Immigration} - \text{Emigration})\)
Key Takeaway for Section 1: A population grows naturally when births exceed deaths. To calculate total population change, you must add net migration (\(\text{Immigrants} - \text{Emigrants}\)) to natural change (\(\text{Births} - \text{Deaths}\)).
---2. Population Density and Distribution
People are not spread evenly across our planet. Geographers describe this using two important concepts:
- Population Distribution: The spatial spread or pattern of where people live across a region or the globe. We describe places as either densely populated (crowded) or sparsely populated (empty/few people).
- Population Density: The average number of people living per unit of area, measured as people per \(\text{km}^2\).
Here is how you calculate density:
\(\text{Population Density} = \frac{\text{Total Population}}{\text{Land Area in km}^2}\)
Common Pitfall: Do not confuse total population size with population density! A giant country like Canada or Russia can have millions of residents, but because its land area is enormous, its population density is actually very low.
Why Do People Live Where They Do?
Where people settle depends on both physical factors (nature) and human factors (society and jobs):
Physical Factors
- Why people settle in high-density areas:
- Flat, low-lying relief and plains: Much easier to build houses, roads, and rail networks.
- Fertile soils and fresh water: Essential for farming crops and drinking supplies.
- Temperate, moderate climates: Reliable rainfall and comfortable temperatures for living and farming.
- Why people avoid sparse areas:
- Extreme climates: Very hot and dry deserts (like the Sahara) or frozen polar biomes make farming and survival extremely difficult.
- Steep, mountainous relief: Mountains (like the Himalayas) are hard to build on and isolate communities.
- Dense rainforests: Inaccessible biomes (like the Amazon basin) with thick vegetation and difficult transport routes.
Human and Socio-Economic Factors
People are naturally drawn to areas that have:
- Plenty of job opportunities and employment hubs.
- Major industrial centers and factories.
- Developed transport infrastructure (highways, railways, ports).
- Good access to healthcare, clean hospitals, and quality schools.
Key Takeaway for Section 2: Population density is \(\frac{\text{Total Population}}{\text{Area in km}^2}\). People choose flat, fertile, temperate areas with good jobs and transport, while avoiding steep mountains, extreme deserts, and dense rainforests.
---3. Population Structure and Population Pyramids
Population Structure describes the composition of a population broken down by age and sex (gender). Geographers display this data using a special bar graph called a Population Pyramid (or Age-Sex Pyramid).
How to Read a Population Pyramid
- Vertical Axis (Y-axis): Shows 5-year age groups (called cohorts), such as 0–4, 5–9, 10–14, all the way up to 85+. The youngest are always at the bottom and the oldest are at the top.
- Horizontal Axis (X-axis): Shows the number of people (in millions/thousands) or the percentage of the total population.
- Left Side: Conventionally displays Males.
- Right Side: Conventionally displays Females.
Memory Trick: "Men to the Left, because Women are always Right!"
The Three Age Groups (Dependents vs. Workers)
A population is divided into three key groups:
- Young Dependents (Aged 0–14): Children who rely on working adults for food, shelter, and education.
- Economically Active / Working Population (Aged 15–64): People who work, earn wages, and pay taxes to support services.
- Elderly Dependents (Aged 65+): Retired individuals who rely on pensions and healthcare services.
The Dependency Ratio measures how many dependents each 100 working-age people must support:
\(\text{Dependency Ratio} = \frac{\text{Number of Dependents (0–14) + (65+)}}{\text{Number of Working Age People (15–64)}} \times 100\)
Comparing Pyramid Shapes
- Wide Base / Expansive Pyramid (LEDCs / Low-Income Countries, e.g., Niger):
- Shape: A very wide base that quickly tapers to a narrow point at the top.
- Meaning: High birth rate (lots of babies born), but higher death rates and lower life expectancy (few people survive to old age).
- Narrow Base / Constrictive Pyramid (MEDCs / High-Income Countries, e.g., Japan, UK):
- Shape: A narrow base, wide middle, and broad top.
- Meaning: Low birth rate (fewer babies), low death rate, and high life expectancy, leading to an ageing population.
Key Takeaway for Section 3: Population pyramids show males on the left and females on the right. A wide base indicates a high birth rate, while a wide top shows high life expectancy and an ageing population.
---4. The Demographic Transition Model (DTM)
The Demographic Transition Model (DTM) shows how a country's birth rate, death rate, and total population change over time as the country develops economically. It is split into 5 distinct stages:
Stage 1: High Stationary
- Birth Rate: High.
- Death Rate: High (due to disease, famine, and lack of medicine).
- Total Population: Low and stable.
- Example: Isolated tribal societies.
Stage 2: Early Expanding
- Birth Rate: Remains high.
- Death Rate: Falls rapidly (due to cleaner water, better sanitation, improved food supplies, and basic healthcare).
- Total Population: Rapid natural increase / population explosion!
Stage 3: Late Expanding
- Birth Rate: Falls rapidly (due to improved access to contraception, urbanization, and better education for women).
- Death Rate: Continues falling slowly.
- Total Population: Still growing, but at a much slower rate.
Stage 4: Low Stationary
- Birth Rate: Low.
- Death Rate: Low.
- Total Population: High and stable.
- Examples: UK, USA.
Stage 5: Declining
- Birth Rate: Drops below the death rate.
- Death Rate: Remains low, but may rise slightly due to an ageing population.
- Total Population: Begins to experience natural decrease and shrinks.
- Examples: Japan, Germany.
Important Geography Insight: Why do birth rates fall in Stages 3 and 4? It is not just about contraception! Female empowerment, higher educational attainment for women, career opportunities, later marriage ages, and lower infant mortality (parents no longer need to have many children to ensure some survive) are major driving reasons.
Key Takeaway for Section 4: The DTM tracks the shift from high birth and death rates (Stage 1) to low birth and death rates (Stage 4), ending in population decline (Stage 5) as countries develop.
---5. Migration and Population Policies
Push and Pull Factors of Migration
People move from one location to another due to a combination of negative reasons pushing them away and positive reasons attracting them:
- Push Factors (Reasons to leave an origin): Negative conditions such as droughts, armed conflict and war, lack of jobs, famine, or natural disasters.
- Pull Factors (Reasons to move to a destination): Positive attributes such as better job opportunities, a safer living environment, higher wages, and superior healthcare and education.
Managing Populations: Government Policies
When a country's population grows too quickly or declines too rapidly, governments can introduce national policies to influence birth rates:
- Anti-natalist Policies: Strategies designed to reduce birth rates (think: Anti = against).
- Methods: Providing free family planning services, increasing contraception availability, and promoting smaller family sizes (for example, China’s historical One-Child Policy).
- Pro-natalist Policies: Strategies designed to increase birth rates and combat an ageing population (think: Pro = in favor of).
- Methods: Offering subsidized childcare, generous paid maternity and paternity leave, baby bonuses, and family tax incentives.
Key Takeaway for Section 5: Push factors drive people away from home, while pull factors attract them to new places. Governments manage birth rates using anti-natalist policies (to reduce births) or pro-natalist policies (to increase births).
---Quick Chapter Review Checklist
Before moving on, check that you can answer these key revision questions:
- Can you calculate Natural Increase using \(\text{Birth Rate} - \text{Death Rate}\)?
- Can you calculate Population Density using \(\frac{\text{Total Population}}{\text{Area in km}^2}\)?
- Which side of a population pyramid represents males, and which represents females?
- What happens to birth and death rates during Stage 2 of the Demographic Transition Model?
- What is the difference between a push factor and a pull factor?
- Can you define the difference between an anti-natalist policy and a pro-natalist policy?