Population Theories and ModelsPopulation Theories and Models Presented by:

Kumar Nirbhay, Asst. Prof.,Dept. of Geography, H D Jain College, Ara

Natural Increase= Crude Birth Rate – Crude Death Rate

Howyoudoin’?

Malthus’ Theory of PopulationGrowthMalthus’ Theory of PopulationGrowthMalthus’ Theory of PopulationGrowth

In 1798 Thomas Malthuspublished his views on the effectof population on food supply. Histheory has two basic principles:Population grows at a geometricrate i.e. 1, 2, 4, 16, 32, etc.Food production increases at anarithmetic rate i.e. 1, 2, 3, 4, etc.

Old dead guy

Malthus (cont.)Malthus (cont.)

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The consequence of these two principles is thateventually, population will exceed the capacity ofagriculture to support the new population numbers.Population would rise until a limit to growth was reached.Further growth would be limited when:

preventive checks - postponement of marriage (lowering offertility rate), increased cost of food etc.positive checks - famine, war, disease, would increase the deathrate.

Malthusian ideas are often supported by Westerngovernments because it highlights the problem of toomany mouths to feed, rather than the unevendistribution of resources;

Malthus (cont.)Malthus (cont.)

Population growsgeometrically….

Population exceedscarrying capacity…

Population is kept in“check”– preventativeand/or positivechecks

Esther Boserup’s Theory of PopulationGrowthEsther Boserup’s Theory of PopulationGrowthEsther Boserup’s Theory of PopulationGrowth

In contrast to Malthus, instead of too manymouths to feed, Boserup emphasized thepositive aspects of a large population;In simple terms, Boserup suggested that themore people there are, the more hands there areto work;She argued that as population increases, morepressure is placed on the existing agriculturalsystem, which stimulates invention;The changes in technology allow for improvedcrop strains and increased yields. I did the 100

metre dash in a90 metre gym!

Anti-populationists vs. pronatalistsAnti-populationists vs. pronatalists

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Malthus– anti-populationistEchoed in recent debates by Paul Ehrlich, authorof The Population Bomb;Ehrlich believed that the earth’s carrying capacitywould quickly be exceeded, resulting inwidespread famine and population reductions;

Boserup– pronatalist (cornucopian)Echoed in recent debates by Julian Simon, whoopposed Ehrlich by using economic theories; ie.Resources needed to support populations arebecoming more abundant, not scarcer;

The Demographic Transition ModelThe Demographic Transition Model The model of demographic transition suggested that a population's

mortality and fertility would decline as a result of social and economicdevelopment. It predicted that all countries would over time go throughfour demographic transition stages.

 

STAGE 1– High Stationary or Pre-IndustrialSTAGE 1– High Stationary or Pre-IndustrialSTAGE 1– High Stationary or Pre-Industrial

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HIGH BIRTH RATESLittle or no family planningParents have many children because few surviveMany children are needed to work the landChildren are a sign of virilitySome religious beliefs and cultural traditions encouragelarge families

HIGH DEATH RATESDisease and plague (e.g. bubonic, cholera, kwashiorkor)Famine , uncertain food supplies, and poor dietPoor hygiene, no piped clean water or sewage disposal

POPULATION GROWTH-- SLOW

STAGE 1 (continued)STAGE 1 (continued)Birth Rate HighDeath Rate HighNatural Increase LowFertility Rate HighInfant Mortality RateHighExample Region Various isolated communities in the least

developed regions of Africa; war-tornregions (eg Afghanistan, Sudan, Angola);political hotspots (eg North Korea)

Other Characteristics: Characterizes pre-industrial societies. Most of thepopulation is rural and involved in subsistence agriculture.

STAGE 1 PyramidSTAGE 1 Pyramid

Due to high birth rates, the pyramid shape wouldhave a wide base;Due to high death rates, the pyramid would be veryshort in height; concave shape indicates low lifeexpectancy.

STAGE 2– Early Expanding or EarlyIndustrialSTAGE 2– Early Expanding or EarlyIndustrialSTAGE 2– Early Expanding or EarlyIndustrial(Rapid population growth)(Rapid population growth)

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Ehrlich described this stage as the “population explosion”HIGH BIRTH RATES

As STAGE 1FALLING DEATH RATES

Improved medical care e.g. vaccinations , hospitals, doctors, new drugs,and scientific inventionsImproved sanitation and water supplyImprovements in food production in terms of quality and quantityImproved transport to move food and doctorsA decrease in child mortality

POPULATION GROWTH-- RAPID

EARLY STAGE 2 (continued)EARLY STAGE 2 (continued)EARLY STAGE 2 (continued)

Birth Rate HighDeath Rate DecreasingNatural Increase IncreasingFertility Rate HighInfant Mortality Rate HighExample Region Sub-Saharan AfricaOther Characteristics: Characterizes post-industrial societies. Most of the

population is rural, but urbanization is increasing rapidly. Dependency loadbegins to increase rapidly as the young cohort (%<15 yrs old) begins todominate the proportion of the population.

LATE STAGE 2 (continued)LATE STAGE 2 (continued)LATE STAGE 2 (continued)Birth Rate HighDeath Rate LoweredNatural Increase Increasing rapidlyFertility Rate HighInfant Mortality Rate DecliningExample Region Many African countries, Middle East

Other Characteristics: The beginning of the population“explosion”. Often, social and economic problems begin on alarge scale. Urbanization continues to grow rapidly.Dependency load is huge due to a massive, young cohort(<15yrs old).

STAGE 2 PyramidSTAGE 2 Pyramid

As death rates are addressed, the population explosion begins;The height of the pyramid grows to reflect the prevention of moredeaths; shape becomes less concave as life expectancy increases;The width of the base remains large due to the ongoing high birthrates

STAGE 3– Late Expanding or LateIndustrialSTAGE 3– Late Expanding or LateIndustrialSTAGE 3– Late Expanding or LateIndustrial

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FALLING BIRTH RATESFamily Planning utilized; contraceptives, abortions, sterilization, andother government incentives adoptedA lower infant mortality rates means less pressure to have childrenIncreased mechanization and industrialization means less need forlabourIncreased desire for material possessions and less desire for largefamiliesEmancipation of women

DEATH RATES LOWAs Stage 2

POPULATION GROWTH– STILL GROWING BUT SLOWING

EARLY STAGE 3 (continued)EARLY STAGE 3 (continued)EARLY STAGE 3 (continued)Birth Rate DecreasingDeath Rate LowNatural Increase High, but decreasingFertility Rate DecreasingInfant Mortality Rate DecreasingExample Region South and East AsiaOther Characteristics: Birth control is introduced and begins

wide social acceptance. Social and economic issues begin tobe addressed. Dependency load is still large due to a largeyoung cohort group (<15yrs old).

LATE STAGE 3 (continued)LATE STAGE 3 (continued)LATE STAGE 3 (continued)Birth Rate Decreasing to a manageable levelDeath Rate LowNatural Increase Decreasing sharplyFertility Rate Decreasing sharplyInfant Mortality Rate LoweredExample Region Latin America, Tiger EconomiesOther Characteristics: Ends the population explosion. People

choose smaller families due to many social and economicfactors. Urbanization dominates. Population stabilizationbegins. Population continues to grow due to the large youngpopulation reaching childbearing age.

STAGE 3 PyramidSTAGE 3 Pyramid

As birth rates begin to be addressed, the basebegins to stabilize and eventually narrow;Death rates are low and stabilized, meaningthat the pyramid continues to grow higher.

STAGE 4– Low Stationary or LowFluctuatingSTAGE 4– Low Stationary or LowFluctuatingSTAGE 4– Low Stationary or LowFluctuating

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BIRTH RATES LOWFertility rates plunge to below replacement rate (2.1children per woman) because:

Valuation of women beyond childbearing and motherhoodbecomes importantIncreasing value is placed on material goods over family size inmodern industrialized societyWidespread choice of contraception by families

DEATH RATES LOWChild mortality reduced and life expectancy increased dueto:

Capital ($$$) investment in medical technologyWidespread knowledge of healthy diet and lifestyle

POPULATION GROWTH– SLOW OR DECLINING(due to aging societies)

STAGE 4 (continued)STAGE 4 (continued)Birth Rate LowDeath Rate Low with spurts as a result of an aging

societyNatural Increase Low or negativeFertility Rate Near or below replacement rateInfant Mortality Rate LowExample Region MEDC’s, ChinaOther Characteristics: Population growth no longer a social and economic

issue. Birth and death rates fluctuate minimally and natural increase stops.An overwhelmingly urban society. Dependency load is small (large workingage group).

STAGE 4 PyramidSTAGE 4 Pyramid

Birth rates and death rates are low; as fertilitycontinues to decline, an AGING SOCIETY emerges.Pyramid seems to “invert”…

MEDC vs. LEDCMEDC vs. LEDC

Note the quick transition toPhase 3 from the explosionof Phase 2

Note the longer time periodas LEDC’s are “trapped” inPhase 2

Criticism of the DTM…Criticism of the DTM…

The model is an over-generalization of theindustrialized European experience;Model is too rigid in assuming all countriesproceed from stage 1-4; it ignores variablesand exceptions (eg. War, political turmoil);Industrialization is difficult to achieve forLEDC’s in a trading system that protects theindustries of MEDC’s;The model assumes that reductions infertility are a function of increased wealthand industrialization– other factors such asthe status of women and other socialdevelopment are ignored.