1. I. I.Population Dynamics - History A. A.Thomas Malthus (1766-1834) English parson Became concerned that unrestricted population growth would cause demand to exceed availability of resources Predicted widespread poverty and famine Global population < 1 billion Malthusians - People who forecast disaster due to overpopulation Many of Malthus’ predictions did not occur Agricultural improvements (did not foresee) Birth control (rejected on moral grounds) PopClock

2. I. I.Population Dynamics - History B. B.Demographic Transition Theory developed to explain human population dynamics in response to economic development Cohen – Four Stages 1) 1)High birth & death rates (nearly equal but variable)  Growth rate low 2) 2)Death rate falls and becomes less variable, birth rate still high  Growth rate rises, population increases. Mortality transition 3) 3)Birth rate drops, death rate remains low or declines, growth rate slows, population increases. Fertility transition 4) 4)Low birth & death rates (nearly equal, not variable), growth rate low or negative, population larger than before (1) This process has occurred in many developed nations United States, Canada, Japan, Western Europe Mortality and fertility transitions typically due to greater affluence, improved health care, changing social expectations, etc.

5. I. I.Population Dynamics - History B. B.Demographic Transition In recent years death rates in many developing nations have decreased Status of the social and economic changes that will supposedly lead to stable populations is unclear Some neo-Malthusians pessimistic that transition to lower birth rates and stable populations will occur Garrett Hardin - “Lifeboat Ethics” Barry Commoner - Anti-Malthusian Main cause of environmental degradation is inappropriate use of technology, not simple population growth Ecologically sound development more important than population control

6. II. II.Population Dynamics - Theory A. A.Background Understanding human population dynamics requires understanding population theory Earth is a closed system (no immigration/emigration) Population size is dynamic equilibrium between Biotic potential Environmental resistance Two basic growth models Density-independent (exponential) growth Density-dependent (logistic) growth

7. II. II.Population Dynamics - Theory B. B.Density-Independent Growth Population growth with unlimited resources In nature, usually occurs rarely and briefly Limited by maximum reproduction rate for a species Inversely related to generation time Ex - Higher for mouse than human

9. II. II.Population Dynamics - Theory B. B.Density-Independent Growth Not sustainable indefinitely in the real world Assumes/Requires unlimited resources Increasing population density limits ability of individuals to acquire resources Density affects/limits population growth rate C. C.Density-Dependent Growth Based on idea that a given environment only can support a limited number of individuals Carrying capacity Population growth described by logistic growth model Environmental resistance increases as population size increases

13. III. III.Population Dynamics - Trends A. A.Demographics Global population reached 6 billion in Oct 1999 Most population growth currently taking place in developing nations Developing nations contain 80% of global population Percentage of global population growth in developing nations 1950 – 85% Today – 99%

16. III. III.Population Dynamics - Trends B. B.Total Fertility Rate (TFR) TFR = Fecundity 2.0 = Replacement level fertility Global TFR 1950 – 5.0 2007 – 2.60 (48% decrease) Africa – 4.73 (Mali – 7.38, Niger – 7.37) Asia – 2.41 (India – 2.81, China – 1.75) N America – 2.26 (Canada – 1.61, Mexico – 2.39, USA – 2.09) Europe – 1.45 (Lithuania – 1.21, Italy – 1.29, Spain – 1.29) Source: U.S. Census Bureau

17. III. III.Population Dynamics - Trends C. C.Infant Mortality Rate (IMR) Global IMR 1950 – 156 deaths per 1000 births (15.6%) 2007 – 44.0 deaths per 1000 births (4.40%) 72% decrease Europe – 0.76% Africa – 8.03% Source: U.S. Census Bureau

18. III. III.Population Dynamics - Trends D. D.Birth and Death Rates 1950 Birth rate – 37 per 1000 people per year Death rate – 20 per 1000 people per year Growth = 17 per 1000 people per year = 1.7% 2007 Birth rate – 20.2 per 1000 people per year Death rate – 8.4 per 1000 people per year Growth = 11.8 per 1000 people per year = 1.18% Developed nations – 0.22% (0.06 B-D + 0.16 I) Developing nations – 1.38% (1.43 B-D – 0.05 E) Source: U.S. Census Bureau

19. III. III.Population Dynamics - Trends E. E.Age and Life Expectancy Median Age World – 28.0 years Developed nations – 39.2 years Europe – 39.8 years N. America – 32.0 years Developing nations – 25.8 years Africa – 19.3 years Life Expectancy 1950 – 46 years 2007 – 65.7 years Africa – 51.9 years (Swaziland – 32.2 years) Europe – 74.8 years (Andorra – 83.5 years) N. America – 75.9 years (USA – 78.0 years) Source: U.S. Census Bureau

20. III. III.Population Dynamics - Trends F. F.Population Projections - UN 1. 1.Low Variant (TFR  1.35 by 2050) 2050 – 7.68 billion 2150 – 3.2 billion 2. 2.Medium Variant (TFR  1.85 by 2050) 2050 – 9.08 billion 2150 – 9.7 billion 3. 3.High Variant (TFR  2.35 by 2050) 2050 – 10.65 billion 2150 – 24.8 billion 4. 4.Constant Variant (TFR = 2.59) 2050 – 11.66 billion 2150 – 51.2 billion

21. United Nations Population Division

23. IV. IV.Population – Environmental Effects Ehrlich – “Earth can support a larger population of cooperative, far-sighted, vegetarian pacifist saints than of competitive, myopic, meat-eating, war- making typical human beings. All else being equal, Earth can hold more people if they have relatively equal access to the requisites of a decent life than if the few are able to monopolize resources and the many must largely do without. The problems of population, social and economic inequity, and environmental deterioration are thus completely intertwined.”

24. IV. IV.Population – Environmental Effects Not all humans impact the environment equally Industrialized nations currently house 22% of the world’s population but consume 60% of food 70% of energy 75% of metals 85% of wood Generate 75% of CO 2 emissions

25. IV. IV.Population – Environmental Effects B. B.I = PAT (Ehrlich and Holdren) I = Environmental Impact of nation P = Population A = Affluence (reflects consumption) T = Technology (reflected in pollution) Ex – Changes in CFC emissions related to technology, not population Developments in technology historically not directed toward environmental preservation