3Natural increase is the balance between birth rates and death rates Population ChangeOutputsInputsDeathsBirthsNatural IncreaseTotalPopulationEmigrantsImmigrantsMigrationThe total population of an area is the balance between 2 forces of change: natural increase and migrationNatural increase is the balance between birth rates and death rates
13What do you think the reasons are for the changes at each stage?
14Reasons for Stage 1 High Fluctuating Little access to birth controlMany children die in infancy so parents have more to compensateChildren are needed to work on the landSome religions encourage large familiesDeath rates are high due to disease, famine, poor diet, poor hygiene, little medical scienceStage 1Birth RateDeath RateTotalPopulation
15Reasons for Stage 2 Early Expanding Improvements in medical careImprovements in sanitation and water supplyQuality and quantity of food produced improvesTransport and communications improve movements of food and medical suppliesDecrease in infant mortalityBirth RateDeath RateTotalPopulation
16Reasons for Stage 3 Late Expanding Increased access to contraceptionLower infant mortality rates so less need for bigger familiesIndustrialisation and mechanisation means fewer labourers requiredAs wealth increases, desire for material possessions takes over the desire for large familiesEquality of women means they can follow a career rather than just staying at homeStage 3TotalPopulationBirth RateDeath Rate
17Reasons for Stage 4 Low Fluctuating Rates fluctuate with ‘baby booms’ and epidemics of illnesses and diseasesReasons for Stage 4 have improved and it stabilisesTotalPopulationBirth RateDeath Rate
18Stage 5: Declining (or Depleting) Population Is there a Stage 5????Stage 5: Declining (or Depleting) Population
19What limitations do you think there could be with the model? It does not include the influences of migrationIt assumes that all countries will go through the same patternThere is no time scaleReasons for birth rates and death rates are very different in different countriesAnd finally, is there a stage 5?
20The End?Adapted from Alsager School – with thanks.