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Population theory

Population theory. http:// www.greenberg-art.com /. Toons /.Toons,%20Environ/ PopulationTrain.html. Demographic Transition Theory. Stage I. Stage II. Stage III. Stage IV. Birth Rate. Population. Demographic Growth. Death Rate. 1700. 1800. 1900. 2000. 1. Epidemiological transition.

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Population theory

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  1. Population theory

  2. http://www.greenberg-art.com/.Toons/.Toons,%20Environ/PopulationTrain.htmlhttp://www.greenberg-art.com/.Toons/.Toons,%20Environ/PopulationTrain.html

  3. Demographic Transition Theory Stage I Stage II Stage III Stage IV Birth Rate Population Demographic Growth Death Rate 1700 1800 1900 2000

  4. 1. Epidemiological transition • Concept • Focuses on changes over time in the causes of mortality affecting certain populations: • Health conditions. • Disease patterns. • Result in a decline in death rates and an increase of life expectancy. • The society goes through a transition from communicative diseases to degenerative diseases.

  5. 1. Epidemiological Transition Age of communicative diseases Age of receding pandemics Age of degenerative and man-made diseases Degenerative diseases Share of mortality Low Fertility Low Mortality High Fertility High Mortality LI=70 years LI=50 years LI=30 years Communicative diseases High Fertility Decreasing Mortality Time

  6. Malthus’ Theory of Population Growth • In 1798 Thomas Malthus published his views on the effect of population on food supply. His theory has two basic principles: • Population grows at a geometric rate i.e. 1, 2, 4, 16, 32, etc. • Food production increases at an arithmetic rate i.e. 1, 2, 3, 4, etc.

  7. Malthus (cont.) • The consequence of these two principles is that eventually, population will exceed the capacity of agriculture 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 of fertility rate), increased cost of food etc. • positive checks - famine, war, disease, would increase the death rate.

  8. Malthus (cont.) Population grows geometrically…. Population exceeds carrying capacity… Population is kept in “check”– preventative and/or positive checks

  9. 2. The Malthusian Crisis • The “Malthusian crisis” • Available agricultural spaces are limited. • Technical progresses (machinery, irrigation, fertilizers, and new types of crops) are slow to occur. • Increasing incapability to support the population. • If this persists, the population will eventually surpass the available resources. • The outcomes are “Malthusian crises”: • Food shortages. • Famines. • War and epidemics. • “Fix” the population in accordance with available resources. • Necessity of a “moral restraint” on reproduction.

  10. t3 t2 Technological Innovation t1 Resources Population 2. The Malthusian Crisis Quantity Overexploitation Time

  11. 2. The Malthusian Crisis • The Malthusian Crisis has not occurred • Malthus has been criticized on several accounts during the last 200 years. • Religious view (Protestantism), racist and elitist. • Did not foresee the demographic transition: • Changes in the economy that changed the role of children in the industrializing societies. • Failed to account for improvements in technology: • Enabled food production to increase at rates greater than arithmetic, often at rates exceeding those of population growth. • Enabled to access larger amounts of resources. • Enabled forms of contraception.

  12. Global Growth in Population and Grain (Wheat and Rice) Production, 1961-2005

  13. Esther Boserup’s Theory of Population Growth • In contrast to Malthus, instead of too many mouths to feed, Boserup emphasized the positive aspects of a large population; • In simple terms, Boserup suggested that the more people there are, the more hands there are to work; • She argued that as population increases, more pressure is placed on the existing agricultural system, which stimulates invention; • The changes in technology allow for improved crop strains and increased yields.

  14. Anti-populationists vs. pronatalists • Malthus– anti-populationist • Echoed in recent debates by Paul Ehrlich, author of The Population Bomb; • Ehrlich believed that the earth’s carrying capacity would quickly be exceeded, resulting in widespread famine and population reductions; • Boserup– pronatalist (cornucopian) • Echoed in recent debates by Julian Simon, who opposed Ehrlich by using economic theories; ie. Resources needed to support populations are becoming more abundant, not scarcer;

  15. Singapore Population Policyhttp://hs-esl.ism-online.org/files/2011/03/SingaporePopulationReport.pdf

  16. Singapore Population Policy

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