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A scientist places one bacteria in a Petri dish at 9:00 am. The bacteria can reproduce at a rate that doubles its population every minute. The scientist observes that the Petri dish is completely full at 10:00 am.
Warm-Up
1. What do you think will happen after 10 am?
2. In what ways is this example similar to human population growth?
3. In what ways is this example different from human population growth?
The Human Population
Exponential growth – a quantity increases by a fixed percentage in a given time
The world’s population is increasing at 1.15% every year
Industrial Revolution
Year
Human Population Growth Over Time
The Rule of 70
The “Rule of 70” is an easy way to estimate how long it will take a population to double, if you know the growth rate
The Rule of 70
Ex: If a population’s growth rate is 7% a year, how long will it take to double in size?
70/7% = 10 years
The Rule of 70
If a country’s population is increasing at about 2% every year, how long will it take to double in size?
70/2% = 35 years
The Rule of 70
Ex: If a population’s growth rate is 5% a year, how long will it take to double in size?
70/5% = 14 years
The Rule of 70
The world’s population is increasing at about 1.15% every year, how long will it take to double in size?
70/1.15% = 61 years
Human Population Density
Human Population Density
Population Map
Wealth Map
Think About It
343,000Amount by which the population of all European Union countries combined grew in the year 2000.
343,000Amount by which India's population grew in the first week of 2001.
If the world were a village of 100 people, there would be:
60 Asians 14 Africans 12 Europeans 8 Central/South Americans & Caribbean 5 North Americans 1 Oceania
If the world were a village of 100 people, there would be:
80 living in substandard housing 50 suffering from malnutrition 33 lacking access to safe drinking water 24 lacking electricity
WORLD POP.
Developed Countries
Developing Countries
U.S., Canada, Australia, NZ, Japan, Europe
Africa, Asia, Latin American, South
America
• > $10,750 per capita GNI
• 19% of world pop.
• 85% of world’s wealth
• Use 88% of resources
• < $10,750 per capita GNI
• 81% of world pop.
• 15% of world’s wealth
• Use 12% of resources
What Do You Think?
Are developed countries, like the U.S., obligated to help developing countries develop? Should we be sending our money to other
countries to help provide them with food, clean drinking water, etc.?
Are we obligated to offer financial assistance to developing countries, like Haiti, who have suffered a natural disaster?
A Changing Population
Based on the differences between developed and developing countries, which do you expect to be increasing in size faster? Developed or developing?
Population Questions
Should we be concerned with the increasing world population size?
What should be done to slow the rate of growth?