1. Human Population: Growth & Distribution
Chapter 11
Human Population: Growth & Distribution
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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
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3. Warm-Up What is the world population right now?
About 7 billion people
Is that too much?
What is the population of the U.S.?
About 313 million people

4. What do you think?
China’s “one child” policy has dramatically slowed their country’s population growth. Should other countries (such as the U.S.) follow their example? Should the government be able to tell you how many kids you can have?

5. Industrial Revolution
Human Population Growth
Industrial Revolution
better medicine
more money
more food
What kinds of historical events were taking place in the 1700s and 1800s?

6. Human Population Growth
Year Reached
Years to Reach
1 billion
1850
Tens of thousands
2 billion
1930 80
3 billion
1960 30
4 billion
1974 14
5 billion
1987 13
6 billion
1999 12

7. 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? (How many humans can Earth support?)
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8. What do you think?
If we cannot provide the basic necessities for 1 billion people today, how will we provide these necessities to an additional 3 billion people in 2050?

9. http://www. youtube. com/watch

10. Factors Affecting Human Population Size
Population change is calculated as the difference between individuals entering and leaving a population:
Population Change
Births + Immigration
Deaths + Emigration – =
Birth Rate – the number of births per thousand people
Immigration – moving into a country
Death Rate – the number of deaths per thousand people
Emigration – moving out of a country
Zero Population Growth (ZPG) occurs when factors that increase and decrease population size equal each other

11. Crude Birth & Death Rates
Developed countries tend to have lower birth rates & death rates than developing countries.
Why?
Figure 11-3

12. Population Change
The annual rate of population increase is generally expressed as a percentage.
What information can you gather from this map?
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13. Population Size by Country
The world's ten most populous countries in 1998, with projections of population size in 2025.
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14. Population Size by Continent
Population size by region in 1998, with projections of population size in 2025.
There are about 84 million births each year.
97% of new births are in developing countries
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15. Birth & Death Rates Over Time
In developed countries, decreases in death rates are being accompanied by decreases in birth rates over time.
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16. 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.
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18. Population Fertility Rates
Replacement Fertility - Number of children needed to replace the parents
(2.1 in developed countries, 2.5 in developing countries)
Total Fertility Rate (TFR) - Average number of children each woman has in a population
Average TFR (births per woman)
2.8 – Low Income Countries
2.4 – Middle Income Countries
1.7 – High Income Countries
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19. Total Fertility in the United States
Total fertility in the United States had a major increase during the "baby boom" (1946–1964) & is now hovering just below replacement level.
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21. Factors Affecting Fertility Rates
What factors decrease human fertility levels?
(What causes people to have fewer children?)
How do you get a baby astronaut to fall asleep?
You rocket.
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22. 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
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23. TFR (births per woman)

24. Teen Pregnancy
Which industrialized country has the highest teenage pregnancy rate?
How many American teenage girls become pregnant each year?
The United States
733,000 (girls years old)
13,500 (girls 14 and younger)

25. Teen Pregnancy
What is the pregnancy rate for American girls ages 15-19?
Is the teen pregnancy rate increasing or decreasing?
67.8 per 1,000 girls (~7%)
It has decreased 42% since 1990 peak

26. Indicators of Health
“It’s not as if people suddenly started breeding like rabbits; it’s just that they stopped dying like flies.” Peter Adamson
Life expectancy - The number of years a newborn can expect to live
Low Income Countries years
Middle Income Countries years
Upper income Countries years
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28. Indicators of Health
“It’s not as if people suddenly started breeding like rabbits; it’s just that they stopped dying like flies.” Peter Adamson
Infant mortality - Number of babies out of every 1,000 that die within a year of birth
Angola – 182.4
India – 32.3
United States – 6.2
Singapore – 2.3
World Average – 42.1
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29. Infant Mortality Rate vs. GDP

30. Death Rates
Infant death rates are lower in developed countries than developing countries
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31. Think About It
Which age group do you think has the biggest population in Pennsylvania?

32. Pennsylvania

33. Population Age Structure
Age structure refers to the proportion of the population in each age class:
Pre-reproductive (0–14 years)
Reproductive (15–44 years)
Post-reproductive (45 & up)
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35. 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 pre-reproductive individuals. Slower growing populations have a more even age distribution.
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36. Population Age Structure
Age structure of populations with zero growth vs. negative growth.
Populations with zero population growth have nearly equal proportions of pre-reproductive & reproductive individuals; whereas populations with negative growth have a greater proportion of reproductive than pre-reproductive individuals.
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37. Matching Review B C A D Rapid Growth Zero Growth Negative Growth
Slow Growth

38. 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.
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39. 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
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40. Population Age Structure
Populations of developed countries are expected to have an increasingly even age distribution through the year 2025.
Fig.11–14b
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41. Developed vs. Developing

42. Demographic Indicators
Fig.11–15
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43. Demographic Transition
A generalized model of demographic transition

44. Demographic Transition
Preindustrial Stage:
Birth rate and death rates are high & approximately equal
population does not increase
population size is small
Death rate
Birth rate
Total pop.
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45. Demographic Transition
2) Transitional Stage:
death rate decreases because of industrialization, increased food production, & improved health care
birth rate remain high
population grows rapidly
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46. Demographic Transition
3) Industrial Stage:
birth rate drops & eventually approaches a balance with death rate
slowing of population growth
Total pop.
Birth rate
Death rate

47. Demographic Transition
4) Postindustrial Stage:
birth rate & death rates approximately balance
zero population growth
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
Total pop.
Death rate
Birth rate

48. 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.
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49. 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.
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50. 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, 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
India
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51. Case Studies – Population Control in China
Since 1970, China 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
China
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52. Case Studies – Immigration in the U.S.
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
Increasing levels of legal & illegal immigrants are expected
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53. Immigration in the U.S.A.!
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54. U.S. Immigration
"Give me your tired, your poor, Your huddled masses yearning to breathe free, The wretched refuse of your teeming shore. Send these, the homeless, tempest-tost to me, I lift my lamp beside the golden door!"

56. Should the U.S. Discourage Immigration?
Since 1820, the U.S. has admitted almost twice as many immigrants and refugees as all other countries combined
Immigration accounts for about 45% of the United States’ annual population growth

57. Immigration in the United States
Should the U.S. reduce the number of immigrants allowed into the country?
Is the U.S. (or other wealthy countries) obligated to accept immigrants from very poor countries?

58. 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
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