Population Trends: Problems and Prospects

2 A.D A.D A.D B.C B.C B.C B.C B.C B.C B.C. 1+ million years Old Stone Age New Stone Age Bronze Age Iron Age Middle Ages Modern Age Black Death—The Plague A.D A.D A.D Future Billions World Pop. was steady until 2 nd agricultural/ scientific revolutions – then it exploded World Pop. Growth Through History

3 Pop. Growth--the Problem Food Supply Status of Women Health Issues –not enough nutrients in food –lack of medical help Educational Opportunities Environmental Issues –deforestation –erosion –tech./chemicals

4 Sparks to Pop. Growth 2 nd Agricultural Revolution Industrial Revolution Urbanization & Sanitation Advances in Medicine Conquest/Colonization of New Lands Developing Countries –Global Pop. Growth Is Driven by Developing Countries

5 Checks on Pop. Growth Epidemics & Plagues –Bubonic Plague , 1/4 of pop. killed; England loses 4 million Famines –Potato Famine in Ireland –India & China Wars Natural Decrease

6 Important Demographic Equations Growth Rate (%) = Birth Rate – Death Rate +/– Migration = Rate of Natural Increase (%) Population Doubling Time (yrs.) = 70  Rate of Natural Increase

7 Rate of Increase (%) Doubling Time (yrs.) Example (1998) Ireland United States China Costa Rica Yemen Higher rate of increase = shorter doubling time (inverse relationship) Doubling Time = 70 / Rate of Increase

yrs. ago – 250 million: doubling time 16 centuries (1650) 1650 – 500 million: doubling time 170 yrs. (1820) … 2000 – doubling time reduced to 35 yrs. (>7 billion currently)

9 The Demographic Transition Model

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12 1. Stage One Growth Pre-Industrial economy – Crude birth rates & death rates fluctuate freely due to famine, war & disease

13 2. Stage Two Growth Early Industrial Economy - Industrialization = decline of death rates bc of better food access due to agricultural advances; birth rates level off & stabilize

14 3. Stage Three Growth Developed Industrial Economy - Birth rates plummet along w/ death rates as overall pop. climbs Most people survive to old age, no need to replace w/babies

15 4. Stage Four Growth Developed Economies - The post- industrial economy sees birth & death rates converging as pop. growth levels off & stabilizes Nations reach replacement fertility – 2.1 children/couple

5. Stage Five Decline Very low birth rate, a low death rate & a slow decrease of the total pop. 16

17 Demographic Transition Theory 5 Stages: 1.High Birth Rate, High Death Rate 2.High Birth Rate, Declining Death Rate 3.Declining Birth Rate, Low Death Rate 4.Low Birth Rate, Low Death Rate 5.Very Low Birth Rate, Low Death Rate

18 Thomas Malthus Food production increases linearly (arithmetically) while pop. increases geometrically (exponentially)— i.e. the world will not have enough food to support itself

19 Malthus cont… But wait! Technology intervenes! Is Malthus wrong for the future? – Neo-Malthusians argue it’s a problem we will never escape—pop. will outdo technology

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