Population Change (DP IB Geography)

Demographic Transition Model

• Since the Industrial Revolution (1850s), no two country's population have changed in the same way

• However, some similarities can be seen in population growth

• These similarities are shown by the demographic transition model (DTM)

• The model illustrates 5 generalised stages of population change that countries pass through as they industrialise

• It shows how birth and death rates change over time and its effects on the overall population 

• The gap between the birth rate and death rate is called natural change (either an increase or decrease in population)

Demographic transition model

Description of DTM

• The strengths of the model include:

  • It can be applied to different settings 

  • It can help demographers plan for predicted future changes

• The limitations of the model include:

  • Developed in 1929, when many countries were still under colonial rule. The model assumes all countries will follow the same pathway through the stages

  • It fails to take into account the effects of globalisation, migration, natural disasters, pandemics, wars and government policies that impact birth rates, e.g. China’s one-child policy

  • It fails to take into account the decline in fertility rates

  • It is too Euro-centric. The model is based on data from 3 countries (England, Wales and Sweden) that industrialised between the 18th and 20th centuries

  • It is difficult to apply to LICs that are currently industrialising in a shorter time frame due to globalisation

• Current LICs population change has differences:

  • Birth rates in stages 1 and 2 are generally higher in LICs

    • Currently only 1 African country (Niger) has a birth rate of 45 /1000 or more

    • In 2000, 14 African countries were in this situation

  • Death rates have fallen quickly for different reasons

    • Availability and use of modern medicine, particularly vaccinations, has lowered mortality rates significantly

    • However, AIDS has caused the death rate to rise in some countries, particularly sub-Saharan Africa

  • Base populations are different

    • With the overall global growth in population, LICs have a much bigger base population to start with, making the impact of high growth bigger in stage 2 and early stage 3 

    • When India and China entered stage 2, no developed country had a population close to that size

  • Fall in fertility rates have been steeper for countries in stage 3 

    • Mainly due to the availability, reliability and education of modern contraception

Differences in demographic transitions

• Not all countries follow the classic model of transition

  • France essentially skipped stage 2, as their birth rate declined in line with death rates

  • Mexico saw an increase in births in stage 2 as maternal health care improved

  • Ireland saw falling birth rates and rising death rates in stage 2 because of emigration after the Great Famine of 1845-9

Types of demographic transition

Natural Change

• Natural population change occurs when birth and death rates differ in a place

  • If birth rates are higher than death rates then there will be a natural increase

  • If death rates are higher than birth rates there will be a natural decrease

• The crude birth rate is heavily influenced by the age structure of a population

  • For instance, in 2022 the crude birth rate varied globally

  • The overall global crude rate was 17/1000

  • Highest was Niger with 46.86/1000

  • Lowest was South Korea and Hong Kong with 5/1000

• Natural change is calculated as a % by subtracting the crude death rate from the crude birth rate 

• Population also changes when people migrate into and out of an area

• Population change is also influenced by the following key vital rates:

  • Fertility rate

  • Infant mortality rate 

  • Replacement level

  • Net production rate

Fertility rate

• For more accurate measures of fertility, the fertility rate and the total fertility rate (TFR) are used

• These rates apply to women within the main reproductive age range of 15-49 years, rather than to the whole population

• This makes for a more accurate measure of fertility than just the birth rate

• Fertility rate is:

  • The number of live births per 1000 women aged 15-49 years in a given year

• Total fertility rate is:

  • The average number of children that would be born alive to a woman during her lifetime - total family size

    • This assumes that she passes through her child-bearing years conforming to the age-specific fertility rates of a given year

• Factors affecting fertility can be grouped into four main categories:

Categories Affecting Fertility Rates

• The United Nations has predicted that:

• Generally, as health improves the mortality rate in the population decreases, and typically there is an accelerated population growth

• However, fertility levels have been falling faster than expected:

  • The global average fertility rate is around 2.3 children per woman today

  • Yet 50 years ago, the global fertility rate was double, with rates of 4.5 to 7 children per woman across the globe

  • Since then, LICs and MICs have seen rapid falls in fertility, partly due to:

    • Increased status and well-being of children

    • Empowerment of women within society and relationships through strengthening: 

      • Access to education

      • Recognition and participation in the labour force

      • Improved women's rights

Declining global fertility rates over time

• Replacement level fertility is the level at which those in every generation have just enough children to replace themselves in the population

• A total fertility rate of 2.1 children is usually considered a replacement level, below this, and countries see a population decline 

Life expectancy

• This measure indicates the average age of death in a population

• In the past, life expectancy was around 30 years in all regions of the world

• Since the 17th century, life expectancy has steadily increased, although it is unevenly spread

• Industrialising countries saw the largest increase through improved health and access to medicines

• Since the 1900s, average, global life expectancy has risen to above 70 years, although it still varies within and between countries

• in 2021, Japan had the highest life expectancy at close to 85 years and Chad was the lowest at 52.5 years

• Globally, the African continent has the lowest average life expectancy at 61.7 years and Oceania the highest at 79.9 years

• Countries with a life expectancy of below 60 years are found in Sub-Saharan Africa due to conflict, poverty and the AIDS virus

• Yemen, Haiti and Afghanistan have life expectancies of over 62 years, yet in 1950 they were below 37.5 years

Women live longer

• Before the 19th century, this wasn't the case, as many women died in childbirth or complications from childbirth

• In fact, the death rate between men and women was fairly equal

• As countries developed, men became more vulnerable to cardiovascular diseases such as strokes and heart disease, through self-destructive lifestyles such as drinking and smoking

• Men became less active as job roles changed from manual to desk work 

• Men are more likely to be involved in conflict and take bigger risks with their lives

• Biologically, women are more resistant to disease and fat is laid down in the body differently than men

• Environmental changes due to the reduction or eradication of infectious diseases