Causes of Population Change Since 1950

Main Causes of Population Change Since the 1950s

Global population has more than tripled since 1950 (from 2.5 billion to over 8 billion), and significant regional shifts in population size and structure have occurred. Understanding the causes of this change — and why they vary across regions — is a core Unit 4 requirement.

The Three Determinants of Population Change

Population change results from just three processes:
1. Natural increase (or decrease): births minus deaths
2. Immigration: people entering a country/region
3. Emigration: people leaving a country/region

$$\text{Population Change} = \text{(Births} - \text{Deaths)} + \text{(In-migration} - \text{Out-migration)}$$

Causes Operating Since the 1950s

1. Medical Advances and Improved Healthcare

The most significant driver of post-1950 population growth has been the dramatic fall in death rates, especially in developing countries, while birth rates remained high.

• Antibiotics: Penicillin (discovered 1928) became widely available post-WWII; dramatically reduced mortality from bacterial infections (pneumonia, sepsis, tuberculosis)
• Vaccines: Mass vaccination campaigns (polio, measles, smallpox — declared eradicated 1980) dramatically reduced child mortality
• Oral rehydration therapy: Simple treatment for diarrhoeal diseases — a leading killer of children — dramatically reduced infant deaths
• Malaria control: DDT spraying campaigns in the 1950s–60s reduced malaria mortality significantly (though later banned for ecological reasons)
• Maternal healthcare: Improvements in obstetric care reduced maternal mortality
• Result: Death rates fell rapidly in Asia, Africa and Latin America while birth rates remained culturally high — the “demographic gap” producing rapid natural increase

2. The Green Revolution

Agricultural innovations from the 1960s–70s:
- High-yield variety (HYV) seeds for wheat, rice and maize (developed by Norman Borlaug and colleagues)
- Irrigation expansion
- Synthetic fertilisers and pesticides
- Effect: India and Pakistan quadrupled wheat production between 1965 and 1985; Asia avoided the mass famines many demographers predicted; population growth that would otherwise have been constrained by food scarcity was supported

3. Declining Fertility (from 1960s–70s)

As development spread, birth rates began falling:
- Female education expanded — educated women have fewer, later children
- Urbanisation — children become costly dependents, not agricultural labour assets
- Contraception access widened (hormonal contraceptives from 1960; IUDs)
- Government family planning programmes (India from 1952; China’s one-child policy 1980–2015; Indonesia KB programme)
- Rising costs of raising children in developing-world cities
- Result: Global TFR fell from ~5.0 in 1950 to ~2.3 today; natural increase rate slowed

4. Government Policies

Pro-natalist (encouraging births):
- France: comprehensive family support packages (free childcare, housing subsidies) — TFR rose from 1.8 to ~2.0 in the 2000s
- Sweden, Germany: paid parental leave policies
- China’s reversal: two-child (2015) then three-child (2021) policies as population ageing alarmed government

Anti-natalist (discouraging births):
- China’s one-child policy (1980–2015): estimated 400 million births prevented; enforced through fines, job penalties, and in some cases coercive sterilisation; resulted in male-biased sex ratio (107:100 male:female at birth vs normal 105:100)
- India’s sterilisation programmes (controversial in 1970s under Indira Gandhi)
- Indonesia’s Keluarga Berencana (Family Planning) programme — voluntary; successful in reducing TFR from 5.5 to 2.6

5. Wars and Conflict

Population change events since 1950 linked to conflict:
- Korean War (1950–53): ~3 million deaths + mass displacement
- Vietnam War: ~2 million Vietnamese deaths; massive refugee exodus
- Rwandan Genocide (1994): ~800,000 deaths in 100 days; 2 million refugees fled
- Syria (2011–): 400,000+ deaths; 5.5 million refugees, 6.7 million internally displaced — largest refugee population since WWII
- Birth rates in conflict zones often fall dramatically (demographic depression)

6. HIV/AIDS

In sub-Saharan Africa, the HIV/AIDS epidemic (from the 1980s) dramatically increased death rates, particularly among young adults aged 20–40:
- Botswana life expectancy fell from 65 (1990) to 48 (2003) before antiretroviral treatment expanded
- Created unusual population pyramid shapes with missing 25–45 age cohorts
- Left millions of orphans, causing social disruption

7. Economic Conditions

Rapid industrialisation drives urbanisation and fertility decline (China, South Korea, Brazil). Economic crises can suppress fertility temporarily (e.g., Eastern Europe post-1990 collapse).

KEY TAKEAWAY: Population growth since 1950 was primarily driven by falling death rates (medical/agricultural advances) while birth rates remained high in developing regions. Since the 1970s, falling birth rates driven by development, education and policy have slowed growth. Wars, disease (HIV/AIDS) and government policy create regional variations.

EXAM TIP: For any “causes of population change” question, organise your response by cause type (natural increase determinants vs migration; or by period). Always connect a cause to a specific mechanism and outcome (e.g., “Antibiotic availability reduced infant mortality, particularly from pneumonia and sepsis, widening the gap between birth and death rates in developing countries”).

STUDY HINT: Remember that “population change” includes both growth AND structural change (ageing, urbanisation, sex ratio imbalance). Causes like the one-child policy affect structure, not just size.