Population Dynamics » Population change and demographic transition model

What you'll learn this session

Study time: 30 minutes

How populations change over time
The Demographic Transition Model (DTM) and its 5 stages
Factors affecting birth rates and death rates
Population pyramids and what they tell us
Case studies of countries at different stages of demographic transition
How to apply the DTM to real-world situations

Population Change: The Basics

Population change is all about how the number of people in an area increases or decreases over time. This might be your town, your country, or even the whole world! Understanding population change helps us plan for the future - like how many schools, hospitals and homes we'll need.

Key Definitions:

Birth rate: The number of live births per 1,000 people per year.
Death rate: The number of deaths per 1,000 people per year.
Natural increase: The difference between birth rate and death rate (when births exceed deaths).
Natural decrease: When deaths exceed births in a population.
Migration: The movement of people from one area to another.

📈 Did You Know?

It took all of human history until 1804 for the world population to reach 1 billion people. Now we add a billion people every 12-15 years! The world population reached 8 billion in November 2022.

The Demographic Transition Model (DTM)

The Demographic Transition Model shows how populations change as countries develop. It tracks birth rates and death rates through 5 stages as a country becomes more developed. It's like a roadmap of population change!

📈 What the DTM Shows

The DTM shows how birth rates and death rates change as countries develop economically. As countries develop, both rates tend to fall, but at different times, creating periods of population growth or decline.

📖 Why It Matters

Understanding the DTM helps governments plan for the future. Will they need more schools or retirement homes? Will they have enough workers? The DTM gives us clues about what might happen next.

The 5 Stages of the Demographic Transition Model

🏠 Stage 1: Pre-industrial

High birth rate, high death rate

Population grows very slowly or stays the same. People have many children hoping some will survive. Deaths from disease, famine and war are common.

Example: Tribal societies with little healthcare

🏭 Stage 2: Early industrial

High birth rate, falling death rate

Death rate drops due to better food supply, improved sanitation and basic healthcare. Birth rate stays high, causing rapid population growth.

Example: Kenya, Nigeria

🏢 Stage 3: Late industrial

Falling birth rate, low death rate

Birth rate begins to fall as people have fewer children. Education improves, women enter the workforce and contraception becomes available.

Example: Brazil, Mexico, India

🏤 Stage 4: Post-industrial

Low birth rate, low death rate

Both rates are low and roughly equal. Population stabilises with slow growth or slight decline. Women focus on careers and children are expensive to raise.

Example: UK, USA, Australia

💻 Stage 5: Future development

Low birth rate, slightly rising death rate

Birth rate falls below death rate, causing population decline. Ageing population with more elderly people than young. Government may encourage more births.

Example: Japan, Italy, Germany

Factors Affecting Birth Rates and Death Rates

👶 Factors Lowering Birth Rates

Better education, especially for women
Access to contraception and family planning
Women entering the workforce
Later marriage ages
Higher cost of raising children
Declining religious influence
Government policies (e.g., China's former one-child policy)

🏥 Factors Lowering Death Rates

Improved healthcare and medicines
Better sanitation and clean water
Improved food production and nutrition
Vaccination programmes
Better housing conditions
Improved workplace safety
Education about health and hygiene

Population Pyramids: A Window into Demographics

Population pyramids are graphs that show the age and sex structure of a population. They're called "pyramids" because in many countries, they're wider at the bottom (more young people) and narrower at the top (fewer older people).

📈 Stage 2 Pyramid

Wide base, narrow top. Shows high birth rate with many young people. Typical of developing countries like Nigeria.

📈 Stage 4 Pyramid

More rectangular shape. Similar numbers across age groups. Typical of developed countries like the UK.

📈 Stage 5 Pyramid

Inverted pyramid or "coffin" shape. More elderly than young people. Seen in countries like Japan.

Case Study Focus: Japan - A Stage 5 Country

Japan is experiencing population decline with more deaths than births each year. In 2022, Japan's population fell by over 800,000 people.

Challenges:

Ageing population (29% are over 65)
Shrinking workforce
Rising healthcare costs
Rural areas becoming abandoned

Government responses:

Financial incentives for having children
Improved childcare facilities
Encouraging immigration (though limited)
Investing in robotics and automation to address labour shortages

Case Study Focus: Nigeria - A Stage 2 Country

Nigeria has one of the fastest-growing populations in the world, with a high birth rate (35.2 per 1,000) and a falling death rate (11.8 per 1,000).

Challenges:

Providing enough schools and jobs for young people
Strain on infrastructure and services
Environmental pressures from rapid urbanisation
Food security concerns

Government responses:

Family planning programmes
Improving education, especially for girls
Economic development initiatives
Urban planning for growing cities

Limitations of the Demographic Transition Model

While the DTM is useful, it's not perfect. Here are some limitations to consider:

Based on European experience: The model was developed based on what happened in Europe during industrialisation, but other regions may follow different patterns.
Assumes economic development: Not all countries develop in the same way or at the same pace.
Ignores migration: The model focuses on births and deaths but doesn't account for people moving in or out.
Cultural differences: Different cultures have different attitudes toward family size that the model doesn't capture.
Government policies: Policies like China's former one-child policy can change population patterns in ways the model doesn't predict.

Why Population Dynamics Matter

Understanding population change helps us prepare for the future. Different stages of the DTM bring different challenges:

🏠 Challenges of Rapid Growth (Stages 2-3)

Providing enough food, housing and jobs
Building enough schools and hospitals
Environmental pressure from resource use
Rapid urbanisation and growing cities

🏤 Challenges of Ageing Populations (Stages 4-5)

Fewer workers supporting more retirees
Rising healthcare and pension costs
Need for elderly care services
Possible economic slowdown

By understanding the DTM, geographers can help societies prepare for these challenges and develop appropriate policies to address them.