2Population Pyramids – The Basics Population pyramids show a cross section of a population at a particular moment.They divide the population by gender i.e. male and female and by age. The age groups are called cohorts.Gender – male and femaleAge groups or cohorts – usually in 5 year age groups e.g
3What Info Can We Get From A Population Pyramid? As you can see from the population pyramid, the cohort for 20 – 24 year olds is smaller than the cohort for 15 – 19 year olds. Therefore this means that 20 – 25 years ago there was a decline in the birth rate, or that this cohort has been affected by an increased death rate, or that large numbers in this cohort have migrated (or a combination of any of these.)If one cohort is smaller than the one below it, this could be explained by:A decline in birth rateAn increase in death rateMigrationAny combination of these
4Can Population Pyramids Explain What Happened? The simple answer is no, a population pyramid is a descriptive tool.It can only describe what is happening now and in the past in terms of the age and sex of the population.It doesn’t predict patterns in the future.It can’t explain patterns now or in the past.It doesn’t include other features of populations e.g. religion, ethnic group etc.
5Use Your Common Sense!You can make educated guesses about what happened, but be aware that they are just guesses!Why is the female bar wider for 80+ year olds? It might be because females generally have a greater life expectancy than males so tend to live longerWhy is there a bulge in the 35 – 49 cohort for both males and females? It might be because the older ones in this cohort (45 – 49) were born just after World War II when all of the men returned from war and so there was a ‘Baby Boom’ i.e. more babies were born. The younger ones in this cohort were born in the 1960s and so the increase might be due to more free attitudes towards sex.Why is there an indent in the 20 – 29 cohort? This may be due to a decreased Birth Rate in the 1980s due to more women having careers and so leaving having children until they are in their late 20s and 30s. This means that their fertility window is reduced.
6Features of LEDC Pyramids LEDC population pyramids have very narrow tops – this suggests a high Death Rate and a low life expectancyLEDC population pyramids have steeply sloping sides as many people in each successive cohort die – this suggests a high Death RateLEDC population pyramids have many more people in the youthful pyramid base i.e. it looks more pyramid in shape compared to the MEDC pyramidLEDC population pyramids have fairly broad bases – this suggests a high Birth Rate
7Features of MEDC Pyramids MEDC population pyramids have fairly wide tops – which suggests that there is a low Death Rate and high life expectancy. Large numbers of people are living until 80+.MEDC population pyramids have gently sloping sides – this suggests that there is a low Death Rate.MEDC population pyramids have fairly narrow bottoms – which means a fairly low Birth RateMEDC population pyramids tend to have more people in the top half of the pyramid and lower numbers of younger people – this gives a rather top heavy appearance.
8Population in millions Population pyramids are used to show information about the age and gender of people in a specific country.MaleFemaleThere is also a high Death Rate.In this country there is a high Birth RatePopulation in millionsThis population pyramid is typical of countries in poorer parts of the world (LEDCs.)
9In some LEDCs the government is encouraging couples to have smaller families. This means the birth rate has fallen.
10Population in millions MaleFemalePopulation in millionsThe largest category of people were born about 40 years ago.In this country the number of people in each age group is about the same.In this country there is a low Birth Rate and a low Death Rate.This population pyramid is typical of countries in the richer parts of the world (MEDCs.)
11Population in millions MaleFemalePopulation in millionsIn the future the elderly people will make up the largest section of the population in this country.In this country the birth rate is decreasing.This is happening more and more in many of the world’s richer countries.
12Population in thousands MaleFemalePopulation in thousandsThis country has a large number of temporary workers. These are people who migrate here especially to find a job.
13Population pyramid for Mozambique. Population pyramid for Iceland.
20MEDC’s and LEDC’sLook at your 2 Population Pyramids and add the following labels to each pyramid (some can be used more than once).
21Which Labels Go Where? Primary school class sizes fall High birth rate Low death rateLow birth rateHigh death rateNew maternity hospital is neededNew “shopmobility” neededMore Golden WeddingsPublic health inspector happy at creation of new sewer.Parents start to think more about family planningGrandparents are rareRise in taxes to pay for growing dependantsHospital in UK advertises in India for new staff.Grandparents take more responsibility for child careMother sobs over grave of her 6th child dead from typhoid.Large number of elderly people at Bingo.
22Answer The Following...Describe the population of each pyramid and suggest reasons for their shape.Suggest ideas for each pyramids population momentum (How each would look in 25 years time).Give a list of reasons (at least 5 per pyramid) to explain benefits and problems of their population projection.
23Is what you see, what you expected? 25 Years Later...Look at the 2 population pyramids for 2025 and compare them to your (2000) projections.Is what you see, what you expected?