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An illustration: Easter Island

An illustration: Easter Island. Upon its discovery by Westerners in 1722, was poor and had smaller population than vestiges indicated Stone Age culture created monumental statues but had ceased to do so by time of European discovery Why did system collapse?. Easter Island. Population.

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An illustration: Easter Island

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  1. An illustration: Easter Island • Upon its discovery by Westerners in 1722, was poor and had smaller population than vestiges indicated • Stone Age culture created monumental statues but had ceased to do so by time of European discovery • Why did system collapse?

  2. Easter Island

  3. Population • Archaeological evidence suggests settlement by small group of Polynesians around 400 AD, but perhaps as late as 900 AD • Population grew rapidly and probably peaked at about 7,000-10.000 around 1400-1500 AD • By arrival of first Europeans in 1722, population stood at around 3,000

  4. Easter Island statues

  5. Production system • Farming: sweet potatoes, yams, taro, bananas, sugar cane • Chicken as only domestic animal • Fish and shellfish but smaller contribution to diet than elsewhere in Polynesia because of absence of coral reef • Evidence of intensification of production

  6. Social organization • Hierarchical chiefdom • Evidence from very different house types • Oral tradition talks about clans and lineages who had demarcated territories but nevertheless integrated as transport of statues and raw materials from one part of island to another indicate

  7. Evidence of decline • Labor no longer organized to undertake big projects like statue carving and their movement across the island • Island exchange and cooperation declined • No major ceremonial relations • Chiefs lost power, especially their access to surplus production Skeletal evidence of conflict, warfare and even cannibalism

  8. Why decline? • Deforestation: severe already by 1400 • Crucial dependence on palm tree • Palm nut provided food • Fronds for thatch roofs, baskets, mats, boat sails • Trunks for transport and raising of statues • But, this palm tree variety was very slow growing: 40-60 years. This is beyond a generation • If population overshoots, and overuses resources the recuperation time of palm is too long and population will crash

  9. Consequences of deforestation • Soil erosion: negative effects on agriculture • Lack of wood for canoes, then affects fishing ability

  10. Absence of effective response • Institutional failure based on inability to learn from environment in sufficient time • Lack of knowledge: had not put in place controls over rate of use and over population

  11. Population and Migration • Fundamental problem of global environmental change: Balance supply of resources from physical system with demand for these resources from human populations over time

  12. Problems population-resource dynamics • A population “tragedy of the commons” • Problem of incorporating the future

  13. Measuring Population • Static: characteristics • Total • Age distribution • Genders • Urban/rural • Geographic distributions

  14. Measuring population • Dynamic: compare one period to another and one age group to another and calculate rates • Fertility • Mortality • Migration • From these rates develop models that allow for projection and prediction

  15. Malthusian theories of population • Assumptions • Constant "passion between the sexes" • Finite earth • Argument: • Left unchecked, population grows and, by definition, grows exponentially (passion) • After an initial period of strong growth, output as a function of population (labor) exhibits diminishing returns

  16. Pre-industrial Western European Demographic Regime • High mortality: “positive check” • High Fertility • Fertility Controls: “preventive checks” • Celibacy • Age at marriage • Spacing behavior • Contraception

  17. Alternatives to Malthus: Boserup/Simon • Relate technological progress to population growth • Population concentration leads to higher likelihood of technological advance. • Population growth  longer hours, • More labor-intensive techniques  eventually leads to more sophisticated technology Synthesis argument: Lee, Ronald, Malthus and Boserup: A Dynamic Synthesis, In David Coleman and Roger Schofield, The State of Population Theory, Oxford: Basil Blackwell, 1986.

  18. Limits to Malthusian Approach • Explaining emergence of new demographic regimes • How technology might explain shifts • These considerations important, because new regimes have emerged

  19. Demographic Transition • Characterized by a drop in marital fertility • Achieved through "stopping" behavior, i.e. controlling births after having the desired number of children

  20. Demographic transition • Theory and policy • Presented as a development model but link to direct link to development not clear from historical example • Nevertheless basis for current views about population in developing world and underlies policy initiatives

  21. Fertility Declines, Real and Projected

  22. Stabilization Remains a Challenge

  23. Demographic transition: the evidence • Shift from high to low fertility was a result of deliberate family limitation • Transition occurred rapidly once it began • To date, process has been irreversible

  24. Fertility Declines, Real and Projected

  25. Sub-Saharan African Fertility Regime • Low age at marriage • Polygyny: men have many wives, leaving few women celibate • Acceptance of pre-marital and extra-marital sexual relations • Remarriage after widowhood or divorce is the norm • These are all factors that make women susceptible to childbearing throughout their reproductive period of 15-49.

  26. Differences Pre-industrial European and African Regimes • Europe: reduce "exposure" • Africa: spacing behavior Lestaeghe, Ron (1986) On the Adaptation of Sub-Saharan Systems of Reproduction. In The State of Population Theory, David Coleman and Roger Schofield (eds.),Oxford: Basil Blackwell: 212-239.

  27. Characteristics of Sub-Saharan African Social System • Poorly defined or poorly enforced common property systems • Children reared communally (polygyny) • Share “costs” in time or responsibility • Weak conjugal bonds • Lineage holds land • Large families have access to larger share References: Dasgupta; Partha, The Population Problem: Theory and Evidence Journal of Economic Literature, 33, 4, 1995: 1879-1902; Chichilnisky, Graciela, North-South Trade and the Global Environment, TheAmerican Economic Review 84 (4): 851-874.

  28. 65 60 55 50 Life expectancy (years) 45 40 Senegal 35 30 Changes in life expectancy in selected African countries with high and low HIV prevalence: 1950 - 2005 with high HIV prevalence: Zimbabwe South Africa Botswana with low HIV prevalence: Madagascar Mali 1950– 1955 1955- 1960 1960- 1965 1965- 1970 1970- 1975 1975- 1980 1980- 1985 1985- 1990 1990- 1995 1995- 2000 2000- 2005 Source: UN Department of Economic and Social Affairs (2001) World Population Prospects, the 2000 Revision.

  29. Predicted loss in life expectancy due to HIV/AIDS in children born in 2000 Predicted life expectancy Loss in life expectancy due to HIV/AIDS Botswana Zimbabwe South Africa Kenya Zambia Côte d'Ivoire Rwanda Mozambique Haiti Cambodia 0 10 20 30 40 50 60 70 Life expectancy at birth (years) Source: U.S. Census Bureau, 2000

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