1.

Up until the early 1970s, researchers thought that chimpanzees were gentle animals that occasionally defended their territories but otherwise lived in harmony with their neighbors.

Then, from 1974 to 1977, researchers Jane Goodall and Richard Wrangham observed how a large group of chimps repeatedly attacked a smaller neighboring group until every male in that smaller group was dead. (Source of information: Thomas Hayden, "The Roots of War," U.S. News & World Report, April 26, 2004, p. 48.)

2.

Noise is much more than just an annoyance.

In fact, noise can be a type of pollution that produces serious hearing impairments, prevents people from getting adequate rest, contributes to high blood pressure, interferes with productivity, and reduces the our overall quality of life. (Source of information: Noise Pollution Clearinghouse, http://www.nonoise.org/)

3.

President Abraham Lincoln is widely considered to have been a good leader who utilized his resources wisely.

Lincoln's counterpart during the Civil War, Confederate president Jefferson Davis, is viewed as a less effective leader because he shielded incompetent people and refused to make use of talented individuals if he disliked them. (Source of information: Joan E. Cashin, "Jefferson Davis," The Reader's Companion to American History, http://college.hmco.com/history/readerscomp/rcah/html/ah_023100_davisjeffers.htm)

4.

For decades , environmental groups have been painting a grim picture of our planet's health.

In his book The Skeptical Environmentalist, however, Bjorn Lomborg argues that the Earth is actually getting healthier, with less pollution, more forests, and more food. (Matt Ridley, "Bjorn Lomborg: Green Contrarian," Time, April 26, 2004, p. 106.)

5.

Visitors enter the sunken plaza of Washington, D.C.'s World War II Memorial on ramps that pass by two giant arches representing the two fronts of the war, the Atlantic and the Pacific.

In the center of the plaza, fifty-six pillars symbolizing the unity of American states and territories during the war surrond a reflecting pool with fountains and a Freedom Wall covered with 4,000 gold stars, where each star represents 100 Americans who gave their lives in the conflict.

6.

Serving as a caregiver for an ailing loved one can be enormously rewarding because it provides a sense of fulfillment and may lead to deeper and more meaningful relationships.

But new research has revealed that caregivers tend to have weaker immune systems, suffer from depression more than non-caregivers, and are 63 percent more likely than non-caregivers to die prematurely. (Source of information: Claudia Kalb, "How TLC Makes You Sick," Newsweek, May 31, 2004, p. 62.)

7.

The planet Neptune has a rocky core surrounded by a mantle of water, methane, and ammonia ice, followed by an atmosphere composed mainly of hydrogen and helium, and—finally—eight satellites and five rings.

Its neighbor, the planet Uranus, is considered Neptune's twin because it has the same size, a similar internal structure and atmosphere, and similar rings and satellites. (Source of information: James T. Shipman et al., An Introduction to Physical Science, 10th ed., Boston: Houghton Mifflin, 2003, p. 402.)

8.

Classicism, the predominant style of the 18th century, was not very interested in nature and celebrated reason, order, and restraint.

The 19th century romantics, in contrast, were enchanted by nature and believed the natural world to be a source of spiritual inspiration. (Source of information: John P. McKay et al., A History of Western Society, 7th ed., Boston: Houghton Mifflin, 2003, p. 767.)

9.

In 1950, 7 percent of middle-class women were employed outside their homes and earned wages.

By 1960, 25 percent of middle-class women were part of America's workforce. (Source of information: Carol Berkin et al., Making America, 3rd ed., Boston: Houghton Mifflin, 2003, p. 872.)

10.

President Richard Nixon pursued his goal of world stability by visiting the leaders of China and the Soviet Union in order to reduce the tensions between the United States and those two countries.

He was also responsible for a peace settlement with North Vietnam that ended America's involvement in the Vietnam War. (Source of information: Carol Berkin et al., Making America, 3rd ed., Boston: Houghton Mifflin, 2003, pp. 935-936.)