Key terms:

  • demography – study of population
  • birth rate – number of live births per 1000 of the population
  • fertility rate – average number of children per woman
  • death rate – number of deaths per 1000 of the population
  • natural growth – birth rate minus death rate
  • replacement rate- a fertility rate of 2.1 children per woman
  • migration – a permanent change of residence
  • net migration – immigration minus emigration
  • immigrant – a person moving into a country
  • emigrant – a person leaving a country
  • population density – number of people per kmĀ²
  • carrying capacity- number of people an area can support based on its resources and technology

Population explosion


Graph from:

The population explosion was caused by a rapid decline in death rates due to medical and scientific advancements during the Industrial Revolution.

Factors for a high birth rate:

  • poor family planning
  • little access to contraception
  • children required to work on land
  • children support their parents in old age
  • desire to have a son, so parents keep trying
  • religious beliefs or traditions

Factors for a low birth rate:

  • emancipation of women, including education and increased career-mindedness
  • access to contraception
  • high cost of raising children
  • anti-natal policies
  • increased age of marriage
  • urbanisation

Factors for a high death rate:

  • low life expectancy and high infant mortality
  • food scarcity, resulting in starvation
  • lack of medical infrastructure and doctors, so disease can not be treated properly
  • poor hygiene and sanitation allows the easy spreading of disease
  • sexually transmitted diseases such as HIV/AIDS

Factors for a low death rate:

  • long life expectancy and low infant mortality rate
  • good hygiene and sanitation
  • abundant food supply, so no starvation
  • good access to medicine/hospitals

Population pyramids

Population pyramids are used to show the age-sex distribution of a country or area.

LEDC (less economically developed countries) pyramids commonly have:

  • a narrow apex (suggesting that there are few old dependents)
  • a broad base (suggesting that there are many young dependents)
  • a concave slope (suggesting a high death rate)
  • a rapidly tapering top (suggesting a high death rate and low life expectancy)Population pyramid of Uganda
Population pyramid from:

MEDC (more economically developed countries) pyramids commonly have:

  • a wide apex (many old dependents)
  • a narrow(-ing) base (low or falling birth rates)
  • a convex slope and bulging sides (suggests low death rates)

Population pyramid of United Kingdom

Population pyramid from:

Ageing population

Demographers talk about an ageing population, if the percentage of people over the age of 65 increases. This is happening in many European countries (most notably Germany and Italy), as well as in other developed countries eg. Japan.

Benefits of an ageing population

  • Increased development of grey industries (industries catering the needs of old people), such as specialised healthcare and care homes
  • Elderly may pass skills and expertise on to the younger generation
  • Elderly may take care of their grand children, allowing parents to work at full capacity, and they may be active in volunteering or other forms of service

Disadvantages of an ageing population

  • Financial burden of elderly due to retirement: little contribution to economy (often little income) and cost of pension budgets places a strain on the working class – even requiring higher taxation to pay for the pensions
  • Reduced development of infrastructure for younger people eg. schools, playgrounds
  • Fewer people to defend the country


Demographic transition model

The demographic transition model (DTM) groups countries based on population trends to give a perception of development.

File:Demographic Transition010.jpg

Most LEDC’S (less economically developed countries) are in Stage 2 of the demographic transition model. Transition economies are commonly found in Stage 3, while the majority of MEDC’s (more economically developed countries) is in Stage 4.

Overpopulation, underpopulation and optimum population

The carrying capacity of an area is defined by the relationship of population to resources and technology.

Overpopulated areas have too little resources and technologies for the people living there. The opposite is true for underpopulated areas. Areas with an optimum population have found a healthy balance between the available resources/technologies and the number of inhabitants.




You can find the respective case studies at:

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