1. The Human Population Ch. 7
Think of the earth as a living organism that is being attacked by billions of bacteria whose numbers double every forty years. Either the …bacteria dies, or both die. 
- Gore Vidal

2. Scientists Disagree on Earth’s Carrying Capacity
Figure
7.1

3. Scientists Disagree on Earth’s Carrying Capacity
The following graphs show theoretical models of food supply and population size.

4. Populations show two types of growth Exponential J-shaped curve
Population Growth
Populations show two types of growth
Exponential
J-shaped curve
Unlimited Growth
Growth is independent of population density
Logistic
S-shaped curve
Growth affected by environmental stress
Growth is not independent of population density

5. Exponential and Logistic Population Growth: J-Curves and S-Curves
Populations grow rapidly with ample resources, but as resources become limited, its growth rate slows and levels off.
Figure 8-4

6. Carrying Capacity (K)
Exponential curve is not realistic due to carrying capacity of area
Carrying capacity is maximum number of individuals a habitat can support over a given period of time due to environmental resistance (sustainability)

7. Freeways of LA

8. White Boards
What do you think is the human carrying capacity on earth?
(be prepared to explain)

9. Different types of Growth
Exponential growth is when the population and growth rate both increase.
Linear growth is when only the population rate increases. The growth rate is steady.

10. HUMAN DEMOGRAPHY
Demographics – The study of human populations and population trends.
Includes statistics about people such as births (fertility), deaths, life expectancy, migration, gender, race, age structures, and economic status.
Human Population reached 7 billion in 2011

11. POPULATION GROWTH
For most of human history, humans have not been very numerous compared to other species.
It took nearly 72,000 years to reach 1 billion.
150 years to reach 3 billion.
25 years to reach 4 billion.
20 years to reach 5 billion
12 years to reach 6 billion.
Human population tripled during the twentieth century..

12. World Population “Dots” Video
This video represents the growth of the human population since 0 A.D.

13. Human Population History

14. Changes in Population Size
Crude birth rate (CBR)= the number of births per 1,000 individuals per year.
Crude death rate (CDR)= the number of deaths per 1,000 individuals per year.
Global population growth rate =
(CBR- CDR)/ 10
National population growth rate =
(CBR+ immigration) - (CDR + emigration)/ 10
Doubling time (in years)- 70/growth rate

15. Human Population Growth
Exponential Growth
Human population has increased
Rates of growth have also increased
Currently about 2% per year
Doubling Time:
Estimation of how long for a population to double in size
When growth is exponential:
Doubling Time = 70 / annual % growth
70/2.0% = 35 years

16. Shanghai living

17. White Boards
Riddle:
A wealthy, eccentric relative of yours passes away. You are listed as the primary beneficiary on the will. You have two options for collecting the money.
Option 1:$200,000 per day for thirty days.
Option 2: One penny doubled every day for thirty days

18. Solution
Option 1:
30days x $200,000 = $6,000,000
Option 2:
Over $18,000,000!

19. 24 hours of ships

20. Rule of 70
To determine the doubling time of a population, divide 70 by the percentage of growth.
Uses the exponential growth calculation
If the growth rate is 2%, then,
70 ÷ 2 = 35 years

21. 24 hour of airline traffic in US

22. Two Demographic Worlds
Developing countries are poor, young, and rapidly growing.
India, China, Bolivia (S. America), Congo (Africa)
Contain 80% of world population, and will account for 90% of projected growth.
Developed countries are wealthy, old, and mostly shrinking.
United States, Japan, France
Populations often expected to decline.

23. New York City

24. Estimated Human Population Growth

25. Measurements of Population Growth
Fertility Rate - Number of births per 1000 women per year.
Developing countries = ~20
Developed countries = ~10
Total Fertility Rate – Average number of children a woman has in her lifetime.
Congo = 4.41 India = U.S. = 2.1
The replacement level is the total fertility rate required to offset the average number of deaths in a population for the current population to remain stable children per couple newest number

26. White Boards
Is it ethical to tell people how many children they can have?

27. World War II – Born before the war.
Baby Boomers
Gen X
Millennials
iGen

28. Fertility Rate of United States

29. Migration
The movement of individuals between areas.
Emigration: Move out of an area
Immigration: Move into an area

30. Changes in Population Size
Net migration rate- the difference between immigration and emigration in a give year per 1,000 people in the country.

31. Survivorship
Life Expectancy - Average age a newborn can expect to attain in any given society.
Most affected by infant mortality rates.
Strongly correlated with income up to about $4, (U.S.) per person.

32. White Boards
What happens if the number of retirees exceeds the number of working adults?
What are we going to do about this in this in the United States?

33. Life Expectancy
Infant mortality rate- the number of deaths of children under 1 year of age per 1,000 live births.
Child mortality rate- the number of deaths of children under age 5 per 1,000 live births.

34. Life Expectancy

35. Population Growth : Opposing Factors
Pronatalist Forces
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
Boys frequently valued more than girls.

36. Population Growth : Opposing Factors
Most antinatalist forces involve women.
Women are less likely to have children when they have…
Higher education and personal freedom.
More opportunities to earn a salary.
Higher socioeconomic status

37. United States Birth Rate

38. The Demographic Transition
The theory of the demographic transition is the theory that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth.

39. DEMOGRAPHIC TRANSITION
Model of how economic development alters population dynamics.
Preindustrial-slow population growth
Food shortages, malnutrition, lack of sanitation and medicine keep death rates high.
Birth rates tend to match death rates to maintain the population.
Early Transitional- rapid population growth
Hygiene, nutrition, and education improve.
Death rates drop dramatically.
Birth rates remain high initially.
Population increases very quickly.

40. DEMOGRAPHIC TRANSITION CONT’D
3. Late Transitional-stable population growth
Birth rates begin to fall.
Population may have increased from 2x to 4x by this point.
4. Industrial-declining population growth
Transition is complete.
Both death and birth rates are low.
Population is in equilibrium.

41. The demographic transition’s four stages
Population growth is seen as a temporary phenomenon

42. Demographic Transition

43. White Boards
What are other influences that could alter the path a country is on?

44. Age Structure (Population Pyramids)
Distribution of ages in a population at a specific time. Visual representations of age structure within a country for males and females.
Graphed as a population pyramid.
More young people in a population usually means higher growth rates.
The power of teens--The number of people younger than age 15 is the major factor determining a country’s future.

45. White Boards
What do you think the US pyramid would look like?

47. Age Structure Diagrams

48. FUTURE OF HUMAN POPULATIONS
Most demographers believe the world population will stabilize sometime during the next century.
We don’t know what the carrying capacity is?
Projections of maximum population size:
Low 8 billion
Medium billion
High billion

49. The 12 Most Populous Countries in the World

50. Family Planning
Family planning- the regulation of the number or spacing of offspring through the use of birth control.

51. The relationship between economic development and population growth rate for developing nations.

52. Ecological Footprints
Affluence - having a lot of wealth such as money, goods, or property.

53. The IPAT Equation
To estimate the impact of human lifestyles on Earth we can use the IPAT equation:
Impact= Population × Affluence × Technology

55. White Boards
What do you think is the largest city on earth right now? (metro area)

57. The Impact of Affluence
Gross domestic product (GDP)- the value of all products and services produced in a year in that country.
GDP is made up of consumer spending, investments, government spending, and exports minus imports.
A countries GDP often correlates with its pollution levels.

58. What will our future look like?
New York City Billings, Montana

59. White Boards
Do you have any questions?