Chapter 11 Human Population: Growth, Demography, & Carrying Capacity tutorial by Paul Rich

1. Chapter 11 Human Population:Growth, Demography, & Carrying Capacity tutorial by Paul Rich © Brooks/Cole Publishing Company / ITP

2. Outline 1. Factors Affecting Human Population Size birth & death rates 2. Population Age Structure age structure diagrams, developing vs. developed countries 3. Solutions: Stabilizing Human Population computer models, demographic transition 4. Case Studies United States, India, China 5. Human Population & Sustainability © Brooks/Cole Publishing Company / ITP

3. 1. Factors Affecting Human Population Size Human population is currently growing exponentially. • What will be the ultimate size of the human population? • What is Earth's carrying capacity? Fig.1–1 © Brooks/Cole Publishing Company / ITP

4. Births+Immigration Deaths+ Emigration Population Change = – Factors Affecting Human Population Size Population change is calculated as the difference between individuals entering and leaving a population: • birth rate is reported as the number of births per thousand people; • death rate is reported as the number of deaths per thousand people; • zero population growth (ZPG) occurs when factors that increase and decrease population size balance. © Brooks/Cole Publishing Company / ITP

5. Crude Birth & Death Rates Developed countries tend to have lower birth rates & death rates than developing countries (data from 1998). Fig.11–2 © Brooks/Cole Publishing Company / ITP

6. Population Change The annual rate of population increase is generally expressed as a percentage. Note the distribution of growth rates in 1998. Fig.11–3 © Brooks/Cole Publishing Company / ITP

7. Population Size The world's ten most populous countries in 1998, with projections of population size in 2025. Fig.11–4 © Brooks/Cole Publishing Company / ITP

8. Population Size Population size by region in 1998, with projections of population size in 2025. Fig.11–5 © Brooks/Cole Publishing Company / ITP

9. Population Size United Nations projections of human population increase, based on fertilities ranging between 1.7 (low), 2.1 (medium), & 2.5 (high) children per woman. Fig.11–7 © Brooks/Cole Publishing Company / ITP

10. Population Size Average total fertility in 1998 was 2.9 children per woman. The total size of the human population depends upon the year by which the replacement rate of 2.1 children per woman is reached. Fig.11–8 © Brooks/Cole Publishing Company / ITP

11. Total Fertility in the United States Total fertility in the United States had a major increase during the "baby boom" (1946–64) & is now hovering just below replacement level. Fig.11–9 © Brooks/Cole Publishing Company / ITP

12. Factors Affecting Fertility Rates The following are significant factors that decrease human fertility levels: • increase in average level of education & affluence; • decrease in importance of child labor; • increased urbanization; • increased cost of raising & educating children; • increased educational & employment opportunities for women; • decreased infant mortality; • higher average age of marriage; • greater availability of private & public pensions; • greater availability of reliable birth control; • greater availability of legal abortions; • change in religious beliefs, traditions, & cultural norms away from encouraging large families. © Brooks/Cole Publishing Company / ITP

13. Birth Control Typical effectiveness of birth control methods in the United States: Fig.11–10a © Brooks/Cole Publishing Company / ITP

14. Birth Control Typical effectiveness of birth control methods in the United States (continued): Fig.11–10b © Brooks/Cole Publishing Company / ITP

15. Death Rates Infant death rates are lower in developed countries than developing countries. Fig.11–12 © Brooks/Cole Publishing Company / ITP

16. Birth & Death Rates Over Time The rapid growth in the world's population has not resulted from an increase in birth rates, but rather a major decrease in death rates. • death rates have decreased markedly during the past 100 years; • birth rates have also decreased, but not as fast as death rates; • the increasing difference between birth & death rates is what has lead to exponential population growth; • the patterns of change in birth & death rates over time are different for developed vs. developing countries. © Brooks/Cole Publishing Company / ITP

17. Birth & Death Rates Over Time In developed countries decreases in death rates are being accompanied by decreases in birth rates over time. Fig.11–11a © Brooks/Cole Publishing Company / ITP

18. Birth & Death Rates Over Time In developing countries decreases in death rates have not been accompanied by as large of decreases in birth rates over time, leading to major population increase. Fig.11–11b © Brooks/Cole Publishing Company / ITP

19. 2. Population Age Structure Age structure refers to the proportion of the population in each age class: • prereproductive (0–14 years) • reproductive (15–44 years) • postreproductive (45 & up) © Brooks/Cole Publishing Company / ITP

20. Population Age Structure Age structure of a rapidly growing vs. a slower growing population. Rapidly growing populations have pyramid–shaped age structures, with large numbers of prereproductive individuals. Slower growing populations have a more even age distribution. Fig.11–13a © Brooks/Cole Publishing Company / ITP

21. Population Age Structure Age structure of populations with zero growth vs. negative growth. Populations with zero population growth have nearly equal proportions of prereproductive & reproductive individuals; whereas populations with negative growth have a greater proportion of reproductive than prereproductive individuals. Fig.11–13b © Brooks/Cole Publishing Company / ITP

22. Population Age Structure Developing countries are expected to continue to have a pyramid shape through the year 2025, although the age structure will become somewhat more evenly distributed. Fig.11–14a © Brooks/Cole Publishing Company / ITP

23. Population Age Structure Populations of developed countries are expected to have an increasingly even age distribution through the year 2025. Fig.11–14b © Brooks/Cole Publishing Company / ITP

24. Population Age Structure Population age structure of the United States continues to show a bulge as the baby boom generation ages. This has been compared to watching a boa constrictor swallow a pig. Fig.11–15 © Brooks/Cole Publishing Company / ITP

25. 3. Solutions: Stabilizing Human Population In 1972 the projections of a model, published in The Limits to Growth, indicated that if current economic, resource use, & population trends continue then we can expect economic & ecological collapse. • the results of this admittedly crude model challenged basic assumptions of industrial societies that there are no limits to industrial & population growth; • twenty years later the authors updated their work in Beyond the Limits: Confronting Global Collapse, Envisioning a Sustainable Future(Donella Meadows et al. 1992); • despite limitations, computer models are an effective means for exploring possible future scenarios. © Brooks/Cole Publishing Company / ITP

26. Computer Models of Human Population This computer model projects what might happen if the world's population & economy continue to grow exponentially at 1990 levels. Fig.11–18 © Brooks/Cole Publishing Company / ITP

27. Computer Models of Human Population This computer model projects how we can avoid overshoot & collapse to make a fairly smooth transition to a sustainable future by stabilizing fertility at two children per couple. Fig.11–19 © Brooks/Cole Publishing Company / ITP

28. Demographic Transition A generalized model of demographic transition (four stages): Fig.11–20 © Brooks/Cole Publishing Company / ITP

29. Demographic Transition 1) Preindustrial Stage: both birth & death rates are relatively high & approximately equal, such that the population does not increase, & the population size is small. Fig.11–20 © Brooks/Cole Publishing Company / ITP

30. Demographic Transition 2) Transitional Stage: death rate decreases markedly because of industrialization, increased food production, & improved health care; birth rates remain relatively high, such the population grows rapidly. Fig.11–20 © Brooks/Cole Publishing Company / ITP

31. Demographic Transition 5) Industrial Stage: birth rate drops & eventually approaches a balance with death rate, leading to a slowing of population growth. Fig.11–20 © Brooks/Cole Publishing Company / ITP

32. Demographic Transition 4) Postindustrial Stage: birth rate & death rates approximately balance, zero population growth is attained, & the population stabilizes at a size much higher than the preindustrial size; if birth rate declines below death rate negative population growth may even be attained. Fig.11–20 © Brooks/Cole Publishing Company / ITP

33. 4. Case Studies Immigration in the United States: • as fertility decreases, immigration has become a major source of population increase in the U.S.; • in 1998 the U.S. received about 935,000 legal immigrants & 400,00 illegal immigrants; • working immigrants boost the economy in the long run; • increasing levels of legal & illegal are expected. Fig.11–17 © Brooks/Cole Publishing Company / ITP

34. Case Studies Population Control in India: • in 1952 India began the first national family planning program; • the program has been disappointing because of poor planning, inefficiency, low status of women, extreme poverty, & lack of funds; • couples still have an average of 3.5 children because of the belief that they need children to work & care for them in old age. Fig.11–16 © Brooks/Cole Publishing Company / ITP

35. Case Studies Population Control in China: • Since 1970, China, with the world's largest population, has initiated efforts to better feed its people & control population growth; • strict population control measures prevent couples from having more than one child; • although considered coercive, the policy is significantly slowing population growth. Fig.11–16 © Brooks/Cole Publishing Company / ITP

36. 5. Human Population & Sustainability How can governments reduce population growth? • improve access to family planning & reproductive health care; • improve heath care for infants, children, & pregnant women; • encourage development of national population policies; • improve equality between men & women; • increase access to education, especially for girls; • increase the involvement of men in child rearing & family planning; • reduce poverty; • reduce & eliminate unsustainable patterns of production & consumption. © Brooks/Cole Publishing Company / ITP