1.1 Population Dynamics

syllabus_link_buttonDescribe and suggest reasons for the rapid increase in the world’s population in recent times, ‘the population explosion’.

The world has experienced rapid population growth over the last century known as a population explosion.  This rapid growth is putting increasing pressure on the environment in terms of providing resources and absorbing our waste. The main reasons for this rapid growth are:

  • High birth rates in many developing countries which already have large populations
  • Decreasing death rates as medicine and hygiene standards improve.

syllabus_link_buttonDefine the main components influencing population growth – birth rate, death rate and migration.

Population Growth

The two ways in which population levels in a country grow are:

Natural increase:  this is calculated by birth rate – death rate. If more people are being born than are dying then the population level will increase.  Natural decrease would occur when more people are dying than being born.

Net migration gain: this is calculated by immigrants – emigrants.  Countries populations will rise if the number of people arriving (immigrants) exceeds the number of people leaving (emigrants). When calculating total population change both of the above criteria need to be taken into account.

syllabus_link_buttonDescribe the relationship between population growth and resources and explain why problems may result in some areas such as over-population and under-population.

over and underpopulation diagram

Over Population

Countries have a finite (limited) amount of resources and space.  If populations grow continually they will eventually start running out of both space and resources. This concept was identified by a scientist named Thomas Malthus.  He recognised that human population can grow at a much faster rate than humans can increase food supplies. He argued that ultimately areas would become overpopulated and experience declining living standards as resources and space became scarcer.  Eventually there would be events that would force a population reduction such as famine, disease spreading or conflict. Overpopulation has many effects in a country/area:

  • Pressure on housing, often leading to high prices and the emergence of cramped and poor quality housing in slum areas. Slums/favelas are often established on illegal sites.
  • Lack of job opportunities leading to unemployment and significant numbers of people working in the informal sector.
  • Pressure on food supplies which may lead to increasing prices (the poorest people suffer the most).  It also makes countries vulnerable
  • to famines if there is disruption to the food supply (natural disasters, droughts etc).
  • Pressure on state services.  Police, healthcare and education are examples of services that typically become increasingly stretched and suffer declines in quality.

Optimum Population

Optimum population exists at a level at which the population can utilise the available resources to achieve the highest possible standard of living.  Above this level the standard of living declines as more people share the same resources.  It is also possible for countries to be under populated.

Under Population

This occurs when the population could achieve higher standards of living by utilising more of their resources if they had more people to do this.  Under population has several impacts:

  • Lower than possible export earnings of the country
  • Low tax receipts for the government which may result in lower investment in government services.
  • Immigration may increase (perhaps encouraged) as overseas workers are attracted to boost the economic output.

syllabus_link_buttonIdentify and suggest reasons for contrasting patterns of population growth in different world areas as influenced by differences in birth rate, death rate and migration. Factors affecting these influences should be considered such as differences in social, economic and other factors, e.g. government policies and their impact upon birth rates, differences in health care, social and other factors influencing death rates, especially the impact of HIV/AIDS. These factors should be illustrated by reference to selected examples.

Contrasting rates of population growth exist around the world for many reasons.

Birth rates

There are significant contrasts in the birth rate globally.  In many developed countries, the birth rate is low, some even falling below replacement level.

Developed Countries

Improved equality for women in education and the workplace has resulted in many women delaying starting families as they establish careers. High costs of children (loss of earnings, child care, clothing, education etc) have resulted in many families choosing to have less children in order to maintain a higher standard of living. Low infant mortality and child mortality rates ensure that parents believe their children will survive into adulthood. Welfare payments and support from governments for the elderly has reduced the reliance on children in later life.  Most countries have state pensions that provide an income for the retired.

Developing Countries

Many developing countries have had high birth rates for various reasons. Lack of access to birth control (contraception).  This may be due to the relatively high cost of buying contraceptive devices in relation to income, it may be due to living in rural areas with limited access to places to buy/obtain birth control methods or it may be due to religious reasons regarding the use of contraception. The need for children to support the family.  Families that practise subsistence agriculture or have small businesses based in the primary sector often choose to have more children to help build the business or work the land.  Many developing countries do not provide comprehensive social welfare (pension payments, free medical care etc for elderly people) require their children to help support them financially and look after them when they are too old to continue working. High infant and child mortality rates.  Countries with the chance of children dying

The need for children to support the family.  Families that practise subsistence agriculture or have small businesses based in the primary sector often choose to have more children to help build the business or work the land.  Many developing countries do not provide comprehensive social welfare (pension payments, free medical care etc for elderly people) require their children to help support them financially and look after them when they are too old to continue working. High infant and child mortality rates.  Countries with the chance of children dying

Many developing countries do not provide comprehensive social welfare (pension payments, free medical care etc for elderly people) require their children to help support them financially and look after them when they are too old to continue working. High infant and child mortality rates.  Countries with the chance of children dying

High infant and child mortality rates.  Countries with the chance of children dying tend to experience higher birth rates as families want to ensure that they have children that survive into adulthood.  Historical evidence indicates that the birth rate starts to fall after the infant mortality rate falls.

Government Policies

The One Child Policy, China

China introduced the one-child policy in 1979 to restrict population growth.  Rapid population had occurred in the years leading up to the policy and China was starting to experience environmental and social problems.  The one child policy restricted families to having one child, although in rural areas families could apply to have a second child under certain circumstances.  If families had more than one child there were strict financial penalties enforced.

The policy has been relatively successful, birth rates have fallen from a peak off 44 in the 1950’s down to just 12. It is estimated that  without the policy there would have been 300 million more chinese born since 1979.  

The scheme has been credited with significantly slowing population growth although it has a left a legacy of social issues itself.  In 2013 the scheme was relaxed to allow parents who were an only child to have two children.

Death Rates 

Death rates have been falling in most countries.  Many of the developed countries that now have large numbers of elderly people are starting to face rising death rates.  Some of these countries are also experiencing increasing numbers of deaths from lifestyle choices such as obesity, lung cancer, heart disease.

Improvements in medicines & healthcare.  Medical knowledge has progressed significantly with scientists having a much deeper understanding of the body and diseases.  New medicines and vaccines have reduced deaths and illness from many diseases.

Improvements in diet.  With increasing levels of development, advances in agriculture and the impacts of globalisation people generally have access to more food and a wider range of food.  This has led to nutritionally better diets in many of the developing countries.

Clean water and sanitation.  Constant improvements in freshwater supplies have vastly reduced illness from water-borne diseases.   This linked with improved sanitation and waste disposal have led to declining death rates.

Death rates have not fallen in all countries.  War or civil conflict has plagued some countries such as the Democratic Republic of Congo resulting in high death rates.


HIV & AIDS have severely impacted on many sub-Saharan countries such as Uganda and Malawi.  These diseases have affected large proportions of working age people and in many cases been passed onto children during childbirth.  With no cure available the effects of these diseases will be felt well into the future.

Tanzania: Impact of HIV/AIDS

Approximately 1.6 million people are living with HIV in Tanzania.  It is widespread throughout the country but rates are distinctly higher in and around mining communities.  Tanzanias wealth of valuable metals (gold) and minerals (Tanzanite) has led to large scale commercial mining taking place.  Transient populations earning reasonable money have seen the emergence of prostitution. HIV is having a significant economic and social impact on Tanzania.  Significant sums of money are invested in education and the treatment of infected people.  The disease is still being passed on to babies during birth. Many children have been orphaned due to their parents dying from the disease.

syllabus_link_buttonDescribe the consequences (benefits and problems) of different patterns of population growth. Consideration should be given to variations in the size and nature of dependent populations and standards of living.

The rate of births and deaths over time in a country can impact on the standard of living the population enjoy.  The proportion of the countries population that is of working age in relation to the those that are too young or too old can have significant economic and social implications.

Young Dependents

These are the people aged 0-15, dependent on their parents for providing income for food, shelter and basic needs.

Economically Active

These are the people of working age 16 – 64.  They are the working population, although not all may be working, further education/training or disabilities may mean that some of them are not included in the labour force.

Elderly Dependents

These are the people who are aged 65+ who are likely to have retired and do not generate much income.  In developed countries they typically rely on pension payments to support them in later life.  The age of retirement is increasing in many countries as life expectancy increases.

The Dependency Ratio

The dependency ratio is an important concept in Geography.  Governments main source of income is from tax, which is generated through the labour force (income tax, corporation tax, value added tax etc).  If the working population is high in relation to the dependent population then the Government is likely to have more income and the ability to invest more in healthcare, education, infrastructure and other public services. If the dependent population is high in relation to the working population then the government is likely to have many demands on its finances but relatively low income to service these demands.

Youthful Populations

High proportions of young dependents in Tanzania
High proportions of young dependents in Tanzania

Countries with high birth rates are likely to have large youthful populations, especially if they have relatively low life expectancy.  Many Sub-Saharan countries currently have relative large youthful populations. This can have both positive and negative impacts. Youthful populations can have a negative impact on the economy as many women are unable to be part of the workforce due to giving birth and then needing to look after children.  This restricts economic output and growth.  Governments also need to invest significantly in education in order to provide school places for a rapidly expanding number of children. Youthful populations can provide future benefits.  As long as the children have been educated or have skills then there is likely to a large proportion of people entering the workforce and increasing the economic capacity of the country in future years.

Ageing Populations

Most developed countries are facing the issue of ageing populations in which there are an increasing proportion of elderly people.  Long life expectancy and low birth rates have led to this scenario. Ageing populations put pressure on economies as more people are needing care and financial support for many years after retirement.  Most of the cost falls on the government who then need to collect more money from the working population often through higher taxes. Japan is an example of

Japan has been struggling to deal with an ageing population. It has the highest proportion of old dependents (about 23%) and the lowest proportion of young dependents (about 13%) in the world. It has a total fertility rate of only 1.25. This is well below the replacement rate of 2.1.  Japan has resisted large-scale immigration to boost its economically active population in order to preserve its cultural identity.   The country is facing many social problems as services for young people close in many rural areas and investment is increasingly chanelled towards the elderly.

syllabus_link_buttonIdentify and suggest reasons for different types of population structure as shown by age/sex pyramids. Candidates should be able to describe population pyramids and relate them to the different stages of the Demographic Transition Model.

Population Pyramids

These are graphs that display the demographic makeup of a country.  The vertical axis displays the age.  The number or % of the population in each age group is displayed with horizontal bars. Population pyramids very effectively display the countries demography in a single chart. The basic outline shape of a countries pyramid can tell a lot about the level of development.  This makes comparing countries easy but also allows demographers to identify patterns and predict future concerns.

Less Economically Developed Countries (LEDCs)

LEDC-population-pyramidThe wide base represents a high birth rate.

Sharply sloping sides represent a high death, in the lower section, this would be the infant and child mortality rate.

The low height of the pyramid represents low life expectancy.

Pyramids this shape have a high percentage of young dependents.


More Economically Developed Countries (MEDCs)

MEDC-population-pyramidThe narrow base represents a low birth rate.

Steeply sloping sides indicate that very few people die in early life.

The pyramids are tall due to long life expectancy.

Pyramids this shape have a good proportion of the population in the economically active population

The Demographic Transition Model


This is a model that represents the typical changes in a countries population over time as the country develops.  It can be used to predict the future changes that a country is likely to experience. The model shows the relationship between birth rates, death rates and total population.

Early stage of development characterised by high birth rates & high death rates.  Low and stable total population level. As Development increase the death rate falls (better diet, medicine, sanitation & clean water).  The birth rate initially remains high which leads to rapid natural increase. Birth rates then follow death rates as people start to trust that children will survive.  This stage is often linked with improvements in education access and the emergence of women focusing on careers.

The final stage represents many of the developed countries today.  Stable populations with low birth and death rates.

Many Geographers suggest the model needs to be adapted to reflect the future trend predicted for the most developed countries.  Ageing populations will lead to an increase in the death rate while birth rates remain low resulting in natural decrease.

syllabus_link_buttonIdentify the major influences on population density and population distribution. Reference should be made to physical, economic and human factors.

Population Density & Distribution

Population distribution refers to how spread out people are (where they are living).

Population density refers to how many people are living in a certain area (km or miles).  Densely populated refers to an area with many people/km2.  Sparsely populated refers to an area with few people/km2.

Many factors affect the distribution and density of people:

  • Climate: extremes of climate (hot, dry, very cold, very wet) tend to have low population densities.  Very dry and cold places limit the availability of freshwater and the ability to grow food which is essential to support populations.  Very wet places in tropical climates have high risks of disease (malaria, dengue fever etc).
  • Relief: mountainous areas are difficult to build on and face challenges with trade links and transport routes which restricts population sizes.  Flat land is much easier and cheaper to build on and to farm.
  • Trade: Coastal locations or sites by major rivers have traditionally attracted larger populations as these places benefitted from excellent trade links.  Trade supplies resources and creates jobs which attract more people to live in an area.
  • Fertile soils: regions that have fertile soil are able to support large populations.  Modern trade allows us to import food but the ability to produce food locally is still very important.  In the UK, The South East has flat fertile land which historically supplied London with cereals and vegetables.

syllabus_link_buttonDescribe and suggest reasons for population migrations. Reference should be made to internal movements such as rural-urban migration as well as to international migrations both voluntary and involuntary.


Migration is the process of moving to another place to live.  It occurs on a variety of scales, international, national or local.  Most people tend to migrate over shorter distances due to there being fewer difficulties.  International migration requires extensive paperwork and visas and the cost of visiting home increases.

International Migration

Mexico to the USA.

  • Legal & illegal migration of Mexicans to the USA seeking higher wages and improved living conditions.
  • Often to work in seasonal industry or low paid services (agricultural jobs in California).
  • High population growth, comparatively low wages & mechanisation of farming & manufacturing in Mexico has led many people to seek an alternative.
  • The USA has been slowly building a fence along the Mexican border to restrict illegal migration.  The fence pushes illegal migrants to take more dangerous routes through desert areas.

Impact on Mexico:

  • Increase in remittance payments from migrant workers – this money goes directly to families and can be spent on rais¡ng living standards.
  • Decrease in some of the economically active population (more male than female).
  • Loss of skilled workers to the US in search of higher pay

Impact on USA:

  • Increased supply of labour with few rights has provided cheap labour allowing lower production costs benefitting American consumers and export sales.
  • Increasing presence of Spanish in American culture (tv, menus etc).
  • Reduction in jobs available & cultural change has created anti-migrant feelings in some Americans.


Internal Migrations

These are migration patterns that occur within countries.

Rural -Urban Migration

Push and pull factors

This is the movement of people from the countryside into towns and cities.  It is the major cause of urbanisation (natural increase in urban areas also contributes).   It is a process currently occurring largely in the less developed countries.

Push Factors

  • Lack of jobs in rural areas due to mechanisation of farming.
  • Limited provision of higher education
  • Limited range of jobs available (unlikely to work in  IT/media/politics/finance etc)
  • Poorer infrastructure & communications networks
Pull Factors

  • Perceived higher wages & more job opportunities
  • Universities & main medical facilities
  • Entertainment & leisure facilities
  • Often cheaper & more accessible Internet facilities


MEDC trend in which people increasingly choose to live outside urban areas in rural communities.

Push Factors

  • Higher crime rates
  • Higher levels of air pollution
  • Higher noise pollution
  • Higher land values & lack of space
  • Traffic congestion
Pull Factors

  • Safer cleaner environment (family friendly)
  • Less traffic congestion
  • Easy access to out of town malls
  • IT developments leading to home working.
  • Commute into urban area for work.

Test Yourself

Past Paper Style Question Practice

1) Define population explosion. [1 mark]

2) Define economically active population. [1 mark]

3) Identify 3 reasons that some regions are sparsely populated. [3 marks]

4) Describe the problems that an over-populated country is likely to face. [5 marks]

5) Describe the problems that a country with a high HIV/AIDS rate is likely to face [5 marks].

6) Describe the problems that countries with ageing populations face.  You should refer to an example that you have studied. [7 marks]

7) Explain why some countries have high birth rates, You should refer to an example that you have studied. [7 marks]