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    examBoard: Cambridge
    examType: IGCSE
    lessonTitle: Population Structure Changes
Geography - Human Geography - Changing Populations - Population Structure Changes - BrainyLemons
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Changing Populations » Population Structure Changes

What you'll learn this session

Study time: 30 minutes

  • How to interpret population pyramids and what they reveal
  • The demographic transition model and its 5 stages
  • Factors affecting population structure (birth rates, death rates, migration)
  • Population structure differences between HICs and LICs
  • Ageing populations and youth bulges - causes and consequences
  • Case studies of Japan (ageing population) and Nigeria (youthful population)

Population Structure: The Building Blocks of Society

Population structure refers to the composition of a population in terms of age, gender and other demographic characteristics. Understanding population structure helps geographers and planners predict future needs for healthcare, education, housing and employment.

Key Definitions:

  • Population structure: The composition of a population by age and gender.
  • Population pyramid: A graphical representation showing the age and gender distribution of a population.
  • Dependency ratio: The ratio of non-working age population (0-14 and 65+) to working-age population (15-64).
  • Demographic transition: A model showing how populations change over time as countries develop.

Reading Population Pyramids

Population pyramids are bar charts that show the distribution of males and females across different age groups. They provide a snapshot of a country's demographic situation and can help predict future trends.

📊 What Pyramids Tell Us

Population pyramids reveal:

  • Birth and death rates
  • Life expectancy
  • Dependency ratios
  • Gender imbalances
  • Effects of migration
  • Historical events (wars, baby booms, etc.)

👥 Pyramid Shapes

Different shapes indicate different stages of development:

  • Triangular/Pyramid: High birth rates, high death rates (LICs)
  • Bell/Barrel: Declining birth rates, low death rates (NICs)
  • Constrictive/Column: Low birth rates, low death rates (HICs)

The Demographic Transition Model

The Demographic Transition Model (DTM) shows how population structure changes as a country develops economically. It consists of five stages that countries typically progress through as they develop.

🟢 Stages 1 & 2

Stage 1: High birth rates, high death rates, slow population growth.

Stage 2: High birth rates, falling death rates, rapid population growth.

Examples: Historical Europe, some parts of Africa today

🟡 Stages 3 & 4

Stage 3: Falling birth rates, low death rates, slowing population growth.

Stage 4: Low birth rates, low death rates, stable population.

Examples: Brazil, China, UK, USA

🔴 Stage 5

Stage 5: Very low birth rates, rising death rates due to ageing population, potential population decline.

Examples: Japan, Germany, Italy

Factors Affecting Population Structure

Birth Rates (Fertility)

Birth rates vary widely between countries and are influenced by:

  • Economic factors: Cost of raising children, women in workforce
  • Social factors: Education levels, contraception access, marriage age
  • Cultural factors: Religious beliefs, gender roles, family size preferences
  • Political factors: Government policies (e.g., China's former one-child policy)

Death Rates (Mortality)

Death rates have generally declined worldwide due to:

  • Improved healthcare: Vaccinations, antibiotics, maternal care
  • Better sanitation: Clean water, sewage systems
  • Improved nutrition: Food security, varied diet
  • Education: Health awareness, hygiene practices

Migration

Migration can significantly alter population structure:

  • Emigration: Often involves working-age adults, leaving behind the young and elderly
  • Immigration: Usually involves young adults, potentially boosting birth rates
  • Gender-selective migration: Some migration flows are dominated by one gender

Population Challenges: Ageing Populations vs Youth Bulges

👴 Ageing Populations

Causes:

  • Declining birth rates
  • Increased life expectancy
  • Out-migration of young people

Consequences:

  • Increased healthcare costs
  • Pension system strain
  • Smaller workforce
  • Higher dependency ratio
  • Potential economic slowdown

🎓 Youth Bulges

Causes:

  • High birth rates
  • Declining infant mortality
  • Limited family planning

Consequences:

  • Pressure on education systems
  • High youth unemployment
  • Housing shortages
  • Potential social unrest
  • Economic opportunity (demographic dividend)

Case Study: Japan's Ageing Population

Japan has one of the world's oldest populations, with 28% of people aged 65+ (2020).

Causes:

  • Very low fertility rate (1.4 children per woman)
  • High life expectancy (84 years)
  • Limited immigration
  • High cost of living and raising children
  • Work-life balance challenges

Consequences:

  • Labour shortages (declining workforce)
  • Rural depopulation as young people move to cities
  • Rising healthcare costs (40% of government budget)
  • Pension system under pressure
  • Economic stagnation

Responses:

  • Robotics and automation to address labour shortages
  • Encouraging women to join the workforce
  • Raising retirement age
  • Policies to encourage higher birth rates
  • Gradual opening to more immigration

Case Study: Nigeria's Youthful Population

Nigeria has one of the world's youngest populations, with over 40% under age 15.

Causes:

  • High fertility rate (5.3 children per woman)
  • Cultural preference for large families
  • Limited access to family planning
  • Lower education levels, especially for girls

Consequences:

  • Rapid population growth (projected to be world's 3rd largest by 2050)
  • Pressure on schools and education system
  • High youth unemployment (over 40%)
  • Housing shortages in urban areas
  • Potential for social unrest

Responses:

  • Expanding education access, especially for girls
  • Promoting family planning
  • Youth employment initiatives
  • Infrastructure development
  • Harnessing the "demographic dividend" through economic policies

Population Structure Management

Countries use various policies to manage their population structures:

📈 Pro-natalist Policies

Policies to increase birth rates:

  • Child benefits and tax breaks
  • Subsidised childcare
  • Extended parental leave
  • Housing support for families
  • Examples: France, Sweden, Russia

📉 Anti-natalist Policies

Policies to reduce birth rates:

  • Family planning programmes
  • Education campaigns
  • Access to contraception
  • Financial incentives for smaller families
  • Examples: China (formerly), India

Summary: Population Structure Changes

Population structures are constantly changing due to economic development, social changes and government policies. Understanding these changes helps countries plan for future needs and challenges.

Key points to remember:

  • Population pyramids reveal a country's demographic profile and stage of development
  • The Demographic Transition Model shows how populations change as countries develop
  • HICs typically face ageing population challenges while LICs often deal with youth bulges
  • Birth rates, death rates and migration all influence population structure
  • Countries use various policies to manage their population structures based on their specific challenges
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