1. The Human Population

2. Big Idea
The size and growth rate of human population has changed drastically over the last 200 years. Those changes have led to profound changes to almost every place on Earth.

3. Questions to Ponder What is the world’s population?
Do the factors that affect other populations affect humans as well?
Why or why not?

4. This is AFTER we factor in deaths
Q: If 2.8 humans are born every second, then how many are born each day?
people born each day
This is AFTER we factor in deaths
over 88,500,000 people born each year

5. JQ: Which of the following graphs do you think represents the world’s population growth over the next few hundred years (population in vs. time)? Explain.
-or-

6. Studying Human Populations
Describe how the size and growth rate for human population has changed over history
What factors lead to population changes
Analyze populations using Age Structure Diagrams
Define demographic transition

7. Describe what you see on this graph
How long did it take to get to 1 billion, then 2, 3, 4, 5, 6?
How many people are living today?
Did You Know? Basic sanitation was rare even in the medical profession until 1861, when Dr. Ignaz Semmelweis discovered that doctors’ hand washing greatly reduced patient mortality.

8. Why did it take so long to reach 1 billion?
Why do you think it took off around the late 1880s?
Interesting Fact: Of all the humans ever born, approximately 6-7% are alive today.

9. Rapid population growth has led to serious environmental problems

10. Studying Human Populations
Demography: the study of human population
How many people live where?
How long are you expected to live?
How many children are you likely to have.

11. 2 General Categories of Populations
Developed Countries
Higher average income
Slower population growth
Diverse industrial economies
Stronger social support systems
Developing Countries
Lower average incomes
Rapid population growth
Simple, agriculture-based economies

12. Exponential Growth
Exponential Growth: rapid growth often seen as J-Shaped curve on a graph
Is exponential growth sustainable?

13. Forecasting Population Size
Will new schools be needed?
Should we be building more housing?
Should farming practices be improved?
Predictions like this often wrong because human behavior changes

14. POPULATION SIZE

15. Forecasting Population Size
Age Structure: the distribution of ages in a population
Age Structure Diagrams aka Population Pyramids
What is useful about these diagrams?

16. What do age structure diagrams show?
What are the “reproductive years”?
Why is that important in forecasting future population growth?

17. Population Age Structure
Rapid Growth
Guatemala
Nigeria
Saudi Arabia
Slow Growth
United States
Australia
Canada
Male
Female
Zero Growth
Spain
Austria
Greece
Negative Growth
Germany
Bulgaria
Sweden
Fig p. 184

18. QUESTIONS
Which “type” of nation is going to see most of the population growth?
In which “type” of nation do people live longer lives?

19. Forecasting Population Size
Survivorship: percent of population likely to survive to any given age
Survivorship Curves – show how much of the population survives for a given age
Type I
Wealthy, developed countries
Most people live to be very old
Type II
Similar death rates at all ages
Type III
Very poor, undeveloped countries
Many children die

22. PROJECTED WORLD POPULATIONS

23. What causes population to change?
Population Changes =
(births + immigration) – (deaths + emigration)
For world population growth we are only concerned about births and deaths.
Many developed countries would have negative population growth without immigration.

24. Migration: movement INTO (immigration) or OUT of (emigration) an area
Population Change =
(births + immigration) – (deaths + emigration)
Migration: movement INTO (immigration) or OUT of (emigration) an area
U.S. growth continues because of both births and immigration

25. Death rates on the decline… people living longer
Population Change =
(births + immigration) – (deaths + emigration)
Death rates on the decline… people living longer
Why?
Better hygiene, sewage disposal, clean water, medicines, education, access to food, nutrition

26. Life Expectancy
Life Expectancy: average number of years members of a population are expected to live
Improvement in most of world
Lower INFANT MORTALITY

27. Compared to our neighbors

28. Major changes in U.S. over last 100+ years

29. Fertility Rates
Fertility Rate: number of children born each year per 1,000 women
Total fertility rate (lifetime)
Replacement level

30. How have U.S. fertility rates changed?
What does this graph show?
Total Fertility Rate – average number of births in one woman’s lifetime
How have U.S. fertility rates changed?

31. Fertility and Women Two main factors impact fertility rates worldwide
Education level of women (knowledge of family planning)
Economic level of women
Generally:
more education = more wealth = lower fertility rates

33. Rule of 70: Doubling Time
Currently, a city has a population of 10 million. If the population is growing at 10%, when will it reach 20 million? (70/rate = doubling time)
What is the growth rate if the population increases from 200 million to 400 million in 14 years ? (70/doubling time = rate)

34. Review
Describe how the size and growth rate for human population has changed over history
What factors lead to population changes
Analyze populations using Age Structure Diagrams
Terms: Demography, Age Structure, Fertility, Migration, Life Expectancy

35. China’s One-Child Policy
In 1970, the average Chinese woman had about six children.
Since 1979, China has used a system of rewards and punishments to enforce a one-child limit to slow population growth.
In 2005, there were 32 million more males than females in China under the age of 20
Talk About It Is it ethical for governments to limit or encourage human population growth?

36. Diverse World Population
Developed Countries
US, Canada, Japan, Australia, New Zealand and most of Europe. High Per Capita GDP. (1.2 billion people)

37. Comparing a Developed Country
to a
Moderately Developed
Developing (Least Developed)

38. Diverse World Population
Developing (lesser developed)
5.2 billion people
living with very little
97% of population growth

39. Percent of World’s 19 Population 81 0.1 Population growth 1.6 85
Wealth and income 85 15 88
Resource use 12 75
Pollution and waste 25
Developed countries
Developing countries

40. World Growth Rates

41. Strategies for Controlling Growth
Public Advertisements
Economic Incentives
Legal Punishments
Empowering Women
Investments in Education and Family Planning

42. Worldwide fertility rates are dropping

43. Growth Is Slowing but still growing
Medium growth rate – fertility rates decline to replacement level by 2050

44. Review
How do developed and developing (less developed) countries compare?
What are some strategies for reducing population growth?