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Human Population : Growth, Demography and Carrying Capacity

Human Population : Growth, Demography and Carrying Capacity. CHAPTER 7 HUMAN POPULATIONS. Human Population Growth Historically. Early Hunter Gatherers Nomadic, With a Strong Sense of the Earth Practiced Intentional Birth Control Rise of Agriculture Necessary for Survival

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Human Population : Growth, Demography and Carrying Capacity

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  1. Human Population:Growth, Demography and Carrying Capacity CHAPTER 7 HUMAN POPULATIONS

  2. Human Population Growth Historically • Early Hunter Gatherers • Nomadic, With a Strong Sense of the Earth • Practiced Intentional Birth Control • Rise of Agriculture • Necessary for Survival • Animals became extinct via predation and altered habitat • Humans began to cultivate own food

  3. C. Agriculture Gives Rise to Cities • Food Produced in Country, Consumed in City • Food wastes are no longer returned to soil • Soil becomes less productive • Waste of Populations Concentrated in Cities • Population Control in Medieval Societies • Infanticide • Plagues

  4. D. Industrialization • View of Children During Early Phases of Industrial Growth • Valued as cheap source of income and cheap labor • Exponential growth of populations • By 1900s, Birth Rate in Industrialized World Dropped • Rise in standards of living • Safe and inexpensive means of birth control introduced • Increase in the cost of child rearing

  5. MI L L I O NS

  6. Population Projections Over 95% of this increase will take place in “Developing Countries”

  7. Current World Population • Population ClockVital Events (per time unit) Global population was 6,669,203,826 On February 27, 2007 at 6:13 am • The global population grows by: • Nearly 2.3persons per seconds • Nearly 8,343 persons per hour • Over 200,234 persons per day • Over 73 million persons per year

  8. How Much is a Billion? • 1,000 seconds = 16.7 minutes • 1 million-s = 16,677 min = 11.6 days • 1 billion-s = 11,574 days = 31.7 years • 1,000 pennies = ~ 88 ounces = 5.5 pounds • 1 million pennies = 5,500 pounds (~1-Suburban) • 1 billion pennies = 2,750 tons (~2 Space Shuttles)

  9. Human Population Outline • Factors Affecting Human Population Size • Population Age Structure • Influencing Population Size • Carrying Capacity

  10. Human Population Dynamics • There are just three sources of change in population size — • fertility • mortality • "natural decrease" refers to population decline resulting from more deaths than births • migration • Net migration is the number of immigrants minus emigrants

  11. What Is Family Planning? • Definition • Measures enabling parents to control number of children (if they so desire) • Goals of Family Planning • Not to limit births • For couples to have healthy children • For couples to be able to care for their children • For couples to have the number of children that they want

  12. China’s Program • Nation With Best Known Population Control Program • Reasons Chinese Government Initiated Population Control Measures • Freshwater and food at a premium for nation’s population • Country experiencing population momentum • Government Perks / Coercive Measures for Citizen Compliance • Free education and health care • Increased personal and family incomes • Increased legal marrying age for women • Contraceptives, abortions, and sterilizations free of charge • Preferential housing and retirement income

  13. What Methods are Used to Control Births? • Preconception Birth Control Methods • Barrier Methods • Condom • Vaginal sponge • Diaphragm • Spermicides • Hormonal Contraceptives • Pill • Injections and implants • Sterilization • Postconception Birth Control Measures • Intrauterine Device • RU-486 Pill • Abortion

  14. Contraceptive Use Worldwide • People in industrialized countries enjoy easy access to contraceptives while those in LDCs do not. • In the U.S., teens and poor women are least likely to use contraceptives. • Severe problems are associated with teen pregnancy.

  15. Human Population Dynamics • infant mortality rate • IMR • infant deaths per 1000 live births (infant < 1 yr) • 1990: 62 now: 52.4 (normal in 1900: 200)

  16. http://www.povertymap.net/pub/mipwa/sections/w-global/health-sanit/infant-mortality-2.htmhttp://www.povertymap.net/pub/mipwa/sections/w-global/health-sanit/infant-mortality-2.htm

  17. www.tte-online.com/.../table-of-contents/ chem-enc-1.html

  18. Maternal Deaths per 100,000 Live Births Source: WHO, UNICEF, UNFPA Maternal Mortality in 1995: Estimates Developed by WHO, UNICEF AND UNFPA, 2001.

  19. Migration Net migration is the number of immigrants minus emigrants

  20. Overall, the world population is growing at a rate of about 1.7 per cent; if this rate continues, the population will double in 42 years. • Unabated, such a rate would lead to a point about 2000 years hence when the mass of humanity would weigh more, and be larger, than the Earth. • But, the growth rate is decreasing

  21. Rule of 70 • Rule of 70 – standard to determine how long it takes for a population to double. • Focus on: migration, aging, youth bulge, urbanization and new socio-economic-political consequences. • Some countries will double—some will not. • World is in j-curve growth.

  22. Rule of 70 • Assume that the pop doubles every 70 years. • Problem: If the population has a growth rate of 2%, how long will it take for the population to double? • Answer: 70/2 = 35 years to double.

  23. Rates of Global Pop. Changeuse: International Data Base http://www.census.gov/ipc/www/idbnew.html, then Online Demographic Aggregation • CBR (crude birth rate) = # births / 1000 population 1990: 24 now: 20.6 • CDR (crude death rate) = # deaths / 1000 population 1990: 9 now: 8.8 • Growth Rate = (b + i) – (d + e) 1990: 1.5% now: 1.19% • growth rates have come down

  24. Human Population Dynamics • Total fertility rate (TFR) • The average number of children born to a woman • Average in developed countries = 1.5 • Average in developing countries = 3.8 • Worldwide 1990: 3.1 now: 2.76 • Replacement fertility rate (RFR) • The number of children a couple must have to replace themselves • A TFR of 2.1 for developed countries with low infant and child mortality rates • Africa RFR = 2.5

  25. Human Population Outline • Factors Affecting Human Population Size • Population Age Structure • Influencing Population Size • Carrying Capacity

  26. Population Pyramids • Graphic device: bar graph • shows the age and gender composition of a region • horizontal axis: gender • male: left-hand female: right-hand • absolute number of people or % • vertical axis: age • 5-year or 10-year age groups

  27. Population Pyramid with young cohorts Male cohorts Female cohorts

  28. Population Pyramids • Population Pyramids on the Web • High Growth: Afghanistan • Moderate Growth: Mexico • Zero Growth: U.S. • Negative Growth: Austria or Italy

  29. Top Graph: China’s baby boom that peaked in late 1960’s and early 1970’s. Started in 1950’s-now visible as those generations in 2000 were 45-49 years of age. Middle Graph: Birth cohorts rapidly declined. Children born bet 25-29 in 2007 belonged to the smallest birth cohorts after the baby boom. These ind were born bet 1978 & 1985 when family planning took place.

  30. Bottom Graph: Projected population pyramid for 2025 when one can again see the large cohorts that were born between 1985 and 1990. This large number of births is just the “echo effect” of the baby boom bet mid 1960’s and mid-1970’s. Each couple should only have one child according to government policy—so why is the base so large?

  31. Population Pyramids • Population Pyramids on the Web • High Growth: Afghanistan • Moderate Growth: Mexico • Zero Growth: U.S. • Negative Growth: Austria or Italy

  32. Population Pyramids • Population Pyramids on the Web • High Growth: Afghanistan • Moderate Growth: Mexico • Zero Growth: U.S. • Negative Growth: Austria or Italy

  33. Population Pyramids • Population Pyramids on the Web • High Growth: Afghanistan • Moderate Growth: Mexico • Zero Growth: U.S. • Negative Growth: Italy

  34. Factors affecting pop pyramids Medicine Disease Technology War Baby Boomers Natural Disasters • Women deciding to delay family • More attention to health (graying of America) • Gay population increasing!! • Immigration / emigration

  35. Demographic Transition • Movement of a nation from high population growth to low population as it develops economically • Transition as a result of four stages • Stage 1—Birth and death rates are both high • Stage 2—Death rates fall; birth rates remain high; growth rate rises • Stage 3—Birth rates fall as standard of living rises; growth rate falls • Stage 4—Growth rate continues to fall to zero or to a negative rate

  36. The Demographic Transition

  37. Five Stages of the Demographic Transition • Used to be 4, now 5 stages • birth rates, death rates and growth rates systematically change through time as societies change: • modernize, urbanize • gain access to technology

  38. Population Pyramids and Demographic Stages • characteristics shapes of ‘pyramids’ • wide base (true pyramid) • wide middle (bulge), somewhat wider base • urn- or bottle-shaped • reversed pyramid • different shapes--different dynamics

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