1. Human Populations

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

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.

4. Human Population History

5. Population Growth
World War II ( ) killed about 40 million people in 6 years
Global population 2 billion +
Growth about 2% a year
Population growth 40,000,000 per year
Population growth 110,000 per day
At no time did the war offset population growth

6. 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.

7. 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 change.

8. 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 change is the only solution to the population problem.
Wealth and resource distribution must be addressed.

9. 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.

10. Technological Optimism

11. Technological Optimism

12. The Meaning of Finite
You cannot put an infinite amount of anything into a finite space
Therefore we will eventually run out of room
You cannot get an infinite amount of anything out of a finite space
Therefore we will eventually run out of new resources

13. At 2% Per Year
In 573 years there will be one person per square meter over the whole earth
In 1546 years the mass of humanity will equal the mass of the earth
No exponential growth can continue indefinitely

14. What About Interest?
At 2% per year, a penny invested in 1 AD would be worth $1.6 x 1015 in 2000 AD
Total GNP of World = $3.5 x 1012
At 4%, couldn’t be paid in gold because it would outweigh the earth
Works if interest paces growth of economy
Offsets: Inflation, Default, Collapse

15. In the Long Run, All Growth is Limited
Environmental Resistance
Malthusian: Overshoot plus crash
Logistic: Steady Limit
Human Population Will Stop Growing
When?
How?

16. Feedback Positive: Change More Change
More peoplemore babiesmore people…
Negative: Change Opposing Force
More babiesmore expense
Logistic growth
Early positive feedback phase
Final negative feedback phase

17. Carrying Capacity of Earth
Solar Energy about 10,000 times global energy use
Global energy use = sunlight on 20,000 square miles
Globally about 1/3 of arable land is used for crops
If U.S. (5% of population) uses 25% of resources, will take 5 times earth’s resource output to raise everyone to our level

18. Why Many Oppose Population Control
Suspicion of Government
Abuse of Police Powers
Undermine Family Authority
Racial Issues

19. Why Many Oppose Population Control
Economic
Declining markets
Diminished labor pool
Reduced Military Manpower
Reduced Tax Base
Increased Wages and Costs

20. Why Many Oppose Population Control
Religious
Pressure for Abortion
Birth Control
Effects on Sexual Conduct

21. Population Growth Rates

22. What Drives Population Growth?
Despite Vatican stance on birth control, most Catholic countries growing slowly
Fastest growth in Africa and South Asia
Many of the fastest growing countries are Moslem
Economic value of large families (farm labor, elder care and support)
Status attached to high fertility

23. 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.

24. Population Density (persons / square km)

25. “Third World” Originally a Cold War Term First World: U.S. and Allies
Second World: USSR and Allies
Third World: Non-Aligned

26. “Third World” First World: Developed Second World: Semi-Developed
Third World: Non-Developed
Close similarity to Cold War meaning of Third World

27. North vs. South?

28. 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.

29. Corruption Index

30. Estimated Human Population Growth

31. 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.

32. 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.

33. Population Growth Rates
Natural Increase
(Crude Birth Rate - Crude Death Rate)
Total Growth Rate
Includes immigration and emigration

34. 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.
Largely due to curbing infant mortality

35. Life Expectancy-1930

36. Life Expectancy-1960

37. Life Expectancy-1990

39. 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.

41. 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.

42. 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.

43. 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.

44. 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.

45. 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.

46. 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

47. Demographic Transition

48. United States Birth Rate
“Pig in a python”

49. 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.

50. Social Change
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.

51. 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.

52. 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

53. 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 billion
High billion

54. One Last Demographic Effect of Population Growth
Equals
Regulation

55. 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