Population Structure (DP IB Geography): Revision Note

Population Pyramids

• The characteristics of a population, the distribution of age, sex, ethnicity, religion etc, is known as the population structure

• It is the result of changes in:

  • Fertility

  • Mortality

  • Migration

• Two of these characteristics can be shown as an age-sex structure or population pyramid

• This is a graphical illustration of the distribution of a given population, grouped by age and gender

• It can be used to represent a population of any region, city, country or even the world

• As the population grows the shape of the pyramid changes 

• The population pyramid can be used to identify the following groups:

  • Young dependents 

  • Old dependents 

  • Economically active (working population)

  • Dependency ratio 

Features of a population pyramid

• Population pyramids of places change over time

  • They show a place’s population structure at one point in time

  • The shape of the pyramid changes as a country moves through the stages of the demographic transition model

• Population pyramids enable governments, nationally and regionally, to assess the needs of the population for services such as healthcare and education

• This means the governments can estimate and plan for spending

Population pyramid of the USA

• HIC countries such as the USA have a column shape

• Stage 4 of the demographic transition model

• This indicates:

  • Decreasing birth rate 

  • Increasing life expectancy

  • Decreasing death rate 

  • Low infant mortality

  • Larger working age population

Migration

• In some countries, migration can lead to an imbalance in the population structure

• The UAE has significantly more males than females 

  • In the UAE 29% of the population are males between the ages of 25 and 39 whereas only 10.5% of the population are women between 25-39

  • This is the result of the migration of males to the UAE to work in the oil, gas and construction industries

• Rapid population growth in some areas as a result of migration can lead to:

  • Increased pressure on services such as healthcare and schools

  • A shortage of housing

  • Increased traffic congestion

  • Increased water and air pollution

  • Shortage of food

  • Lack of clean water

UAE population pyramid

Japan's ageing population 

• Japan's population fell from 128 million in 2007 to 125.8 million in 2020

• The fertility rate is 1.36 births per woman which is well below the 2.1 fertility replacement rate

• The birth rate is 6.8 per 1000

• The death rate is 11.1 per 1000 

  • The death rate has increased from 6 per 1000 in 1979

  • This is not because healthcare or diets are worse but because there are far more elderly people who are more likely to become ill and die

• Japan has the highest life expectancy in the world at 84.36 years

Japan from a pyramid to a column?

• By 2085, although the population of Japan will have shrunk overall, the pyramid shows a relatively stable population; one that isn’t growing or shrinking

• The bars are about equal in all age groups, but become smaller at the top as people in the older age groups die

• Populations with pyramids this shape have just about a replacement fertility and higher life expectancy 

Mexico's shrinking population

• Mexico has a replacement fertility rate of just 1.8 (a TFR of 2.1 represents replacement level)

  • The reducing birth rate is due to out migration of young males

• The median age in Mexico is 29.8 years

Mexico - from expanding to contracting

• From 1960 to 2022 the population of Mexico increased from 37.8 million to 127.5 million people - a growth of 237.6% in 62 years

• The country represents 1.6% of the global population

• Peak population growth occurred in 1965 at 3.34% and since then it has steadily declined. In 2022 population growth was just 0.63%

• Median age has risen from a low of 15.1 years (1970) to 29.8 years (2022)

• Life expectancy is 75 years - females 78.4 and males 71.8 years

• Death rate decreased from 13 (1960) to 5 (2008) but increased to 7(2019) and further increased to 9.34/1000 in 2021, where it has remained

• Infant mortality has declined from 159.6 per 1000 in 1950 to 10.5 per 1000 (2022)

• Working age population stands at approximately 67%, however, by 2067 it is estimated it will be less than 60% with an ever increasing elderly population and decreasing young population

Dependency Ratio

• Population structures and pyramids can be divided into three age-group categories, depending on the level of economic activity

  • Young dependents - from 0-14 years, they rely on their economically active parents to support them

  • Economically active - from 15-64 years, they are the working population who earn income, pay taxes and contribute to the support of the young and elderly

  • Elderly dependent - from 65 years onwards, they are no longer economically active and so rely on support from the state and younger family members

• The amount that the young and elderly dependent population of a place depends on the economically active population can be measured 

  • This is expressed as the dependency ratio

• The higher the percentage of working-age people, the more income is being produced for a country to support those of non-working ages

• An ageing population would have a high dependency ratio – as would a population with a very high birth rate

• The dependency ratio tends to be:

  • Due to youthful population structure with many young dependents

    • In Niger the figure was 105 in 2021

    • This means for every 100 people of working age, 105 economically inactive young and elderly depend on them

  • Due to a large elderly dependent sector of the population

    • In Japan the figure was 57 in 2021

  • Due to few elderly dependents because previously there was low life expectancy

  • Also due to small number of young dependents because birth rates are falling

    • In Mexico the figure was 48 in 2021

  • Very high in LICs in stage 2 of the demographic transition model

  • High in advanced HICs in stage 4 and 5 of the demographic transition model

  • Lower in MICs in stage 3 of the demographic transition model

Examples of the Dependency Ratio

The dependency ratio describes how much pressure an economy faces in supporting its non-productive population

Dependency ratio limitations

• It assumes that people under 15 years and over 65 years (65+) are outside of the labour force

  • UK has a retirement age of 67 years (and set to increase) and minimum working age and hours

• It assumes that everyone aged 15-64 are working

  • UK has a school leaving age of 18 years