Upload
donna-fleming
View
225
Download
0
Tags:
Embed Size (px)
Citation preview
The Human Population
World Population
2200
2047
2024
2012
1999
1987
1975
1960
1930
1830
What Kept the Human Population in Check For
So Many Centuries?
• Disease!
• Smallpox, Diptheria, Measles & Scarlet fever kept the child population down
• Tyhus, Cholera and the Black Plague (14th century) kept the adult population in check
Why the Explosion?
• Discovery of infectious agents• Production of vaccines• Discovery of penicillin• Treatment of sewage
World Population Growth Rate and Absolute Growth
Why is Growth Rate Decreasing?
• Lower fertility rates• 5.0 in 1960 to 2.7 kids/woman
today
United Nations Population Projections
& Fertility Rates
Economic Divisions of the World
Different Worlds• High-Income, Developed/Industrialize
• 971 million, 2003• Gross national income per capita (GNI) = >$9386, average
$28 550
• Middle-Income, Moderately developed• 3 billion• GNI = $766-$9385, average = $1920
• Low-Income, Developing countries• 2.3 billion• GNI < $765, average = $450
Fertility• 98% of world population growth is occuring in
developing countries!
• A fertility rate of 2.0 will ensure a stable population if we ignore infant and child mortality, and women who do not reproduce
• Replacement-level fertility is actually 2.1 in developed countries and higher in developing countries due to the above factors
• Fertility rates in developed countries now averages 1.6 (lowest = 1.3), whereas in developing countries it averages 2.9 (highest 4.0)
• Doubling time with a fertility rate at 1.6 is 700 years
• Doubling time with a fertility rate of 2.7 is 58 years
Population Growth in Developed & Developing
Countries
Rural Populations in Developing Countries
• What is happening to populations based on small-scale agriculture?
• What options do they have to survive?
1. Reform the system of land ownership2. Intensify cultivation3. Open up new land to farm4. Engage in illicit activities for income5. Emigrate (legally or illegally)6. Move to cities & seek employment
City Growth
4035302520151050
Comparing Age Structure in the USA
1985, 2005, 2050
Comparing Age Structure in Italy
Comparing Age Structure in a
Developing Country
This projection is based on the assumption that there will be a decline in fertily rate from 4.8 to 2.7 by 2025
Comparing Projected Populations
2005
2050
Homework
• Answer question 12 in the back of the chapter, to be handed in for a mark for next week.
• This will be marked like a free-response question on your AP exam, only I will be marking you more severly as you will have more time to answer and the book to help you
• Do not use words like « it » and « they »