Population Structure (SL IB Geography)

• 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

Generalised 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 can be applied to 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

• 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