2. Human Population History

3. LOSSES: Mortality and Emigration
Mortality - Death Rate.
Survivorship - Percentage of cohort surviving to a certain age.
Life expectancy - Probable number of years of survival for an individual of a given age.
Increases as humans age.
Life Span - Longest period of life reached by a given type of organism.
Emigration - Movement of individuals out of a population.

4. Identify most likely influences
Given a long list of possible factors promoting growth, for a specific case, what leads to overpopulation or extinction?
Identify most likely influences
(create a simplified “model”)
Test the predictions of the model

6. Changing birth rates: opposing factors
Factors that increase the desire for children
Personal
Source of pleasure, pride, comfort.
Source of support for elderly parents.
Current source of family income.
Social Status
Government policy
Labor availability
Tax and social welfare balances

7. Birth Reduction Pressures
Good times
Education and socioeconomic status are usually inversely related to fertility in wealthier countries.
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
Bad times
Food & violence uncertainty

8. Infant Mortality and Women’s Rights

9. Fig. 9.10

10. Birth Rates in the United States

11. Fig. 9.11

12. Fig. 9.12

13. Population “momentum”
Fig. 9.13
Population “momentum”

14. 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.

15. 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.
But is this hypothesis accurate?

16. Demographic Transition

17. Fig. 9.15

19. What are the consequences of large numbers of people?

20. Pessimistic View

21. Optimistic View

22. Questions for discussion
What defines human “carrying capacity”?
How do these factors change birth or death rates to stabilize population size?
For national policy makers around the globe, what should be considered in setting policy about birth rates?

23. …the U.S. can be called the most over-populated nation.
Erhlich & Ehrlich, Environmental Law (vol. 27, no. 4) 1997

24. If every one of the 6 billion of us lived in Texas…room enough for each family of four to have a house and 1/8 acre…
Moore, National Review (Oct. 25, 1999)

25. …the answer often focuses on crowding…these views miss the point…
Erhlich & Ehrlich, Environmental Law (vol. 27, no. 4) 1997

26. …energy use seems to be a priori a reasonable measure…
Erhlich & Ehrlich, Environmental Law (vol. 27, no. 4) 1997

27. Life expectancy is the best overall numerical measure of human well-being
Moore, National Review (Oct. 25, 1999)

28. Population growth is a sign of mankind’s greatest triumph - our gains against death
Moore, National Review (Oct. 25, 1999)

29. It’s hard to argue with somebody who despairs because mankind is alone at the top of the food chain.
Moore, National Review (Oct. 25, 1999)

30. …the key is regulation of birth rates…
Erhlich & Ehrlich, Environmental Law (vol. 27, no. 4) 1997

31. capitalism is by far the best contraceptive
Moore, National Review (Oct. 25, 1999)

32. Assuming human progress and scientific advancement continue as they have… …12 billion people will be richer, healthier and better fed than the 6 billion of us today…
Moore, National Review (Oct. 25, 1999)

33. In a rational world, Malthusianism would be [in]…thorough disrepute…every objective trend is running in precisely the opposite direction…
Moore, National Review (Oct. 25, 1999)

34. By assaulting the earth’s ecosystems, humanity is…sawing off the limb on which it perches.
Erhlich & Ehrlich, Environmental Law (vol. 27, no. 4) 1997

35. "We now have in our hands—really, in our libraries—the technology to feed, clothe, and supply energy to an ever-growing population for the next seven billion years."
Simon, The Ultimate Resource, 1981

36. "There is no reason to believe that at any given moment in the future the available quantity of any natural resource or service at present prices will be much smaller than it is now, or non-existent."
Simon, The Ultimate Resource, 1981

37. Paul Ehrlich and Human Populations
Why is zero population growth counter to Natural Selection?