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Population pyramids show the structure of a population by comparing relative numbers of people in different age groups.

Population structures differ markedly between Less Economically Developed Countries LEDCs and More Economically Developed Countries MEDCs.

• The shape of a population pyramid can tell us a lot about an area's population.

• Usually pyramids are drawn with the % of male population on the left and % of female population on the right.

• It gives us information about birth and death rates as well as life expectancy.

• A population pyramid tells us how many dependants there are. There are two groups of dependants; young dependants (aged below 15) and elderly dependants (aged over 65).

• Dependants rely upon the economically active for economic support. These are people of working age between 15 and 65.

• Many LEDCs have a high number of young dependants. Because of the large number of young people, the population pyramid will have a wide base and the sides of the pyramid will decrease as fewer people will reach old age. Most people younger than 15 tend not to be economically active (although this is not the case in some LEDCs) so the more young dependants there are, the more pressure that puts on the economically active population. On the other hand, these young people will enter the economically active age groups eventually, producing more wealth for the country.

• However, many MEDCs have a growing number of elderly dependants. The large proportion of older people results in the pyramid having straight sides or a barrel shape. The pyramid will also be much taller as people are living longer. People older than 65 tend not to be economically active, although some are. As with young dependants, elderly dependants rely on the wealth created by the economically active population. Older people may be more likely to have savings and so will create less pressure on the economy. On the other hand, their medical and other needs may be greater than young dependants.

A population pyramid can be drawn up for any area, from a whole continent or country to an individual town, city or village.

The shape of the population pyramid can help us to understand the population structure for a place and help us interpret the birth rate, death rate and life expectancy for a place.

The following graphs show the population pyramids of an MEDC (the UK) and an LEDC (Mozambique), for 2000 and in 2025 using projected figures.

MEDC (aged dependent) population pyramid

Notice how in the UK 2000 pyramid there is a bulge in the area of the 30-34 and 35-39 age groups, with the numbers thereafter reducing fairly steadily as the ages increase. This matches stage 4 of the demographic transition model.

Compare this to the 2025 pyramid, which would be stage 5 in the model. Here the bulge extends much further, covering the age groups 30-64, with the numbers beginning to reduce significantly only after 64.

The population structure for the UK shows an aged dependent population. The sides of the pyramid are steep which indicates that few people die before they reach old age.

The majority of children will be surviving beyond 65 or further. Life expectancies are high because health services are good.

LEDC (Youth dependent) population pyramid

Now compare the UK population pyramids with those for Mozambique:

In this graph, notice that in 2000 the 0-4 age group contained the largest number of people, with the numbers thereafter decline steadily as the ages increase. The graph matches stage 1 in the model.

In the second graph, the largest group in Mozambique in 2025 is still the 0-4 age group, but there are nearly as many people in the 5-29 age groups. Now the population pyramid matches stage 2.

Mozambique could be described as having a youth dependent population.

The birth rate is very high (shown by the wide base at the 0 – 4-year-old cohort).

The birth rate remains steady and high but each year a number of people will die so that much fewer people will reach the age of 65.

Although there have been improvements in health care in recent years, there are still large numbers of people who are dying as a result of diseases such as HIV/AIDS, malaria and cholera.

A very large percentage of the population are younger than 15, so the population is said to be youthful.

Most MEDCs are experiencing slow rates of population growth and some are experiencing population decline.

Most MEDCs are in stage 4 of the demographic transition model - the population is high, but not growing.

Some countries have a declining population and could be said to be entering stage 5.

This means that the birth rate in their country has fallen below the death rate. Most MEDCs have a very low rate of natural increase.

The average life expectancy in MEDCs is rising. This is due to:

• improvements in health care and medicine;

• increased leisure and recreation time;

• improved knowledge about the importance of a balanced diet and regular exercise;

• improved living standards and quality of life.

Birth rates in MEDCs are falling as people choose to have smaller families later in life. Contraception is easily available and well understood.

• As people live longer, the structure of a population changes.

• Many MEDCs are now experiencing a significant increase in the number of elderly people as a proportion of the population.

• As birth rates fall and people have smaller families, the number of young dependants is falling and the number of elderly dependants is rising.

• In the near future this will mean that there are fewer economically active people to support the elderly population.

• To try to balance out an ageing population, some countries adopt a pro-natalist policy - that is, they encourage people to have more children by offering them benefits, such as access to childcare and maternity leave.

Implications of an aged dependent population

Many LEDCs have experienced very fast growth in recent years.

Birth rates remain very high but there is an ever-increasing number of people living in the economically active group (from 15 to 65 years old).

As a result many LEDCs have moved from Stage 1 in the demographic transition model to Stage 3 very quickly.

The high birth rate in LEDCs results in a high proportion of the population under 15. This youthful population gives a country specific problems.

The problems include:

• Young children need health care - for example, immunisations. This is expensive for a country to provide.

• Young people need to be educated - providing schools and teachers are expensive. Resources for lessons are difficult to access, and costly to buy.

• In the future, more children will reach child bearing age, putting more pressure on the health service.

Implications of a youthful dependency population