Human Populations

1. Human Populations Chapter 7 Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

2. Outline: • Population Growth • Limits to Growth • Human Demography • Fertility and Mortality • Life Span and Expectancy • Population Growth - Opposing Factors • Demographic Transition • Family Planning • Future of Human Populations Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

3. POPULATION GROWTH • Until the Middle Ages, human populations were held in check by diseases, famines and wars, and thus grew very slowly. • It took all of human history to reach 1 billion. • 150 years to reach 3 billion • 12 years to go from 5 to 6 billion • Human population tripled during the twentieth century. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

4. Human Population History Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

5. LIMITS TO GROWTH • Thomas Malthus (1798) argued human populations tend to increase exponentially while food production is plentiful. • Humans inevitably outstrip food supply and eventually collapse. • Human population only stabilized by positive checks. • Humans are too lazy and immoral to voluntarily reduce birth rates. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

6. Karl Marx • Population growth is a symptom rather than a root cause of poverty and other social problems. • Real causes of these problems are exploitation and oppression. • The way to slow population growth and alleviate many social problems is through social justice. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

7. Malthus and Marx Today • Neo-Malthusians - Believe we are approaching, or have already surpassed, the earth’s carrying capacity. • We should make over-population issues our first priority. • Neo-Marxists - Believe eliminating oppression and poverty through social justice is the only solution to the population problem. • Wealth and resource distribution must be addressed. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

8. The Role of Technology • Technological optimists argue that Malthus was wrong in his predictions because he failed to account for scientific progress. • Current burst of growth was stimulated by the scientific and industrial revolutions. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

9. Can More People be Beneficial ? • More people mean larger markets, more workers, and increased efficiency due to mass productions. • Greater numbers also provide more intelligence and enterprise to overcome problems. • Human ingenuity and intelligence. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

10. HUMAN DEMOGRAPHY • Demography - Encompasses vital statistics about people such as births, deaths, distribution, and population size. • October 12, 1999, UN officially declared the human population reached 6 billion. • Estimation at best. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

11. Population Density (persons / square km) Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

12. Two Demographic Worlds • First is poor, young, and rapidly growing. • Less-developed countries. • Africa, Asia, Latin America • Contain 80% of world population, and will account for 90% of projected growth. • Second is wealthy, old, and mostly shrinking. • North America, Western Europe, Japan. • Average age is about 40. • Populations expected to decline. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

13. Estimated Human Population Growth Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

14. Fertility and Birth Rates • Crude Birth Rate - Number of births in a year per thousand. (Not adjusted for population characteristics) • Total Fertility Rate - Number of children born to an average woman in a population during her life. • Zero Population Growth - Occurs when births plus immigration in a population just equal deaths plus emigration. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

15. Mortality and Death Rates • Crude Death Rate - Number of deaths per thousand persons in a given year. • Poor countries average about 20 while wealthier countries average about 10. • Some rapidly growing countries have very low crude death rates compared to slower growing countries, due to a higher proportion of young people in the population. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

16. Population Growth Rates • Natural Increase • (Crude Birth Rate - Crude Death Rate) • Total Growth Rate • Includes immigration and emigration Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

17. Life Span and Life Expectancy • Life Expectancy - Average age a newborn can expect to attain in any given society. • Declining mortality is the primary cause of most population growth in last 300 years. • Worldwide, average has risen from 40 to 65.5 over the past century. • Greatest progress has been in developing countries. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

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19. Demographic Implications of Living Longer • A population growing rapidly due to natural increase has more young people than a stationary population. • Both rapidly and slowly growing countries can have a problem with dependency ratio. • The number of non-working compared to working individuals in a population. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

20. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

21. Emigration and Immigration • Emigration and Immigration play a large role in human population dynamics. • Developed regions expect 2 million immigrants a year for next 50 years. • Immigration is a controversial issue. “Guest workers” often perform dangerous or disagreeable work, while being paid low wages with few rights. • Locals complain immigrants take away jobs and overload social services. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

22. POPULATION GROWTH, OPPOSING FACTORS • Pronatalist Pressures • Factors that increase the desire for children. • Source of pleasure, pride, comfort. • Source of support for elderly parents. • Current source of family income. • Social Status • Replace members in society as they die. • Boys frequently valued more than girls. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

23. Birth Reduction Pressures • Higher education and personal freedom for women often result in decisions to limit childbearing. • When women have more opportunities to earn a salary, they are less likely to have children. • Education and socioeconomic status are usually inversely related to fertility in wealthier countries. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

24. Birth Reduction Pressures • In developing countries, higher income often means families can afford more children, thus fertility often increases. • In less-developed countries, adding another child to a family usually does not cost much, while in developed countries, raising an additional child can carry significant costs. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

25. United States Birth Rate Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

26. DEMOGRAPHIC TRANSITION • Model of falling death rates and birth rates due to improved living conditions accompanying economic development. • Pre-Modern Society - Poor conditions keep death rates high, thus birth rates are correspondingly high. • Economic Development brings better conditions and standard of living thus death rates fall. Birth rates stay constant or even rise. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

27. Demographic Transition • Eventually, birth rates begin to fall. • Populations grow rapidly in time between death rates and birth rates fall. • Developed Countries - Transition is complete and both death and birth rates are low and population is in equilibrium. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

28. Demographic Transition Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

29. Optimism or Pessimism • Some demographers believe the Demographic Transition is already taking place in developing countries, and world population should stabilize during the next century. • Others argue that many poorer countries are trapped in the middle phase of transition, and that their populations are growing so rapidly that human demands exceed sustainable resource yields. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

30. Social Justice • Still other demographers believe that in order for the Demographic Transition model to work, resources must be distributed more equitably. • The world has enough natural resources, but inequitable social and economic systems cause maldistribution. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

31. FAMILY PLANNING • Family Planning allows couples to determine the number and spacing of their children. • Birth Control - Any method used to reduce births. • Traditional Methods • Long breast-feeding, taboos against intercourse while breast-feeding, celibacy, folk medicines, abortion, infanticide. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

32. Birth Control • Current Methods • Avoidance of sex during fertile periods. • Mechanical barriers preventing contact between sperm and egg. • Surgical prevention of sperm or egg release. • Chemical prevention of sperm or egg maturation, release, or implantation. • Physical barriers to implantation. • Abortion Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

33. FUTURE OF HUMAN POPULATIONS • Most demographers believe the world population will stabilize sometime during the next century. • Projections of maximum population size: • Low 8 billion • Medium 9.3 billion • High 13 billion Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

34. Summary: • Population Growth • Limits to Growth • Human Demography • Fertility and Mortality • Life Span and Expectancy • Population Growth - Opposing Factors • Demographic Transition • Family Planning • Future of Human Populations Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

35. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.