Essentials of Ecology

S12 SUPPLEMENT 3

High-income: $10,800 or more

Upper middle-income: $3,500–$10,799

Lower middle-income: $900–$3,499

Low-income: $899 or less No data available

10,000 B.C.

8,000 B.C.

2,000 B.C.

1,000 A.D.

1347–1351

1500

1750

1800

1804

1845–1849

1927

1943

1952

1957

1961

1974

1984

1987

2011

2024

2042

End of last Ice Age 4 million

50,000 B.C. Hunter-gatherer societies 1.2 million

Year Event

Human

population

Agricultural Revolution 5 million

Contraceptives in use in Egypt

500 B.C. 100 million

250 million

Black Death (Plague); 75 million people die

450 million

Industrial Revolution begins in Europe 791 million

Industrial Revolution begins in the United States

1 billion

Irish potato famine: 1 million people die

2 billion

Penicillin used against infection

Contraceptive pill introduced

Great famine in China; 20 million die

3 billion

4 billion

5 billion

6 billion

Projected human population: 7 billion

Projected human population: 8 billion

Projected human population: 9 billion

Figure 3 High-income, upper middle-income, lower
middle-income, and low-income countries in terms of
gross national income (GNI) PPP per capita (U.S. dol-
lars) in 2006. (Data from World Bank and International
Monetary Fund)

Data and Map Analysis

1. In how many countries is the per capita average
   income $899 or less? Look at Figure 1 and find the
   names of three of these countries.


2. In how many instances does a lower-middle- or low-
   income country share a border with a high-income
   country? Look at Figure 1 and find the names of the
   countries involved in three of these instances.

Figure 4 Population timeline, 10,000 B.C.–2008.

Data Analysis

1. About how many years did it take the human
   population to reach 1 billion? How long after
   that did it take to reach 2 billion?


2. In about what year was the population half of
   what it is projected to be in 2011?