The public ceremonies of the Plains Indians are lesser elaborate than those of the Navajo in the Southwest.

In some species of fish, such the three-spined stickleback, the male, not the female, performs the task of caring for the young.

When she retires in September 1989, tennis champion Christine Evert was the most famous woman athlete in the United States.

The ancient Romans used vessels equipped with sails and banks of oars to transporting their armies.

Dinosaurs are traditionally classified as cold-blooded reptiles, but recent evidence based on eating habits, posture, and skeletal structural suggests some may have been worm-blooded.

Since the great depression of the 1930's, social programs such as Social Security have been built into the economy to help avert severity business declines.

In the 1970's, consumer activities succeeded in promoting laws that set safety standards for automobiles, children's clothing, and a widely range of household products.

Zoos in New Orleans, San Diego, Detroit, and the Bronx have become biological parks where animals roams free and people watch from across a moat.

In human beings, as in other mammal, hairs around the eyes and ears and in the nose, prevent dust, insects, and other matter from entering these organs.

The Rocky Mountains were explored by fur traders during the early 1800's, in a decades preceding the United States Civil War.

The works of the author Herman Melville are literary creations of a high order, blending fact, fiction, adventure, and subtle symbolic.

Each chemical element is characterized to the number of protons that an atom of that element contains, called its atomic number

The body structure that developed in birds over millions of years is well designed for flight, being both lightly in weight and remarkably strong.

From 1905 to 1920, American novelist Edith Wharton was at the height of her writing career, publishing of her three most famous novels.

In the early twentieth century, there was considerable interesting among sociologists in the fact that in the United States the family was losing its traditional roles.

Although pure diamond is colorless and transparent, when contaminated with other material it may appear in various color, ranging from pastels to opaque black.

Comparative anatomy is concerned to the structural differences among animal forms.

A seismograph records oscillation of the ground caused by seismic waves, vibrations that travel from its point of origin through the Earth or along its surface.

Electric lamps came into widespread use during the early 1900"s and have replaced other type of fat, gas, or oil lamps for almost every purpose.

Located in Canada, the Columbia Icefield covers area of 120 square miles and is 3,300 feet thick in some places.

Composer Richard Rodgers and lyricist Oscar Hammerstein II brought to the musical Oklahoma! extensive musical and theatrical backgrounds as well as familiar with the traditional forms of operetta and musical comedy.

Because of its vast tracts of virtually uninhabited northern forest, Canada has one of the lowest population density in the world.

Rice, which it still forms the staple diet of much of the world's population, grows best in hot, wet lands.

Government money appropriated for art in the 1930's made possible hundreds of murals and statues still admiration in small towns all over the United States.