Bartering was a basic trade mechanism for many thousands of years; often sporadic and usually based on notions of reciprocity, it involved the mutual exchange of commoditi...

  The wet rice fields of Asia are the most productive of all preindustrial intensive agricultural systems. As the term 'wet rice' suggests, the method involves flooding the fi...

The physical and chemical properties of water, unsurprisingly, determine much about life in the ocean. Water is dense (high mass per unit of volume), about 840 times as dense as ai...

Both the steamboat and the railroad system with its steam-powered trains revolutionized transport in the United States in the nineteenth century. Entire regions that would hardly h...

There is a much greater similarity between the flowering plant floras of different continents—South America, Africa, Asia, and Australia—than between the mammalian faunas  (anim...

By the twentieth century, making workers more “cost-efficient” had become the single most important management goal in large-scale industries. Everywhere in industrial America ma...

  Personality Traits Trait theory is a major approach to the study of human personality. Trait psychologists are interested in measuring personality traits, which are endurin...

Underground Water The hydrosphere is the collective mass of water at or near Earth’s surface. Beneath the land surface is the underground water component of the hydrosphere. The ...

  The seventeenth century was a golden age for Dutch painting, with artists producing genre paintings (depictions of scenes from everyday life), still lifes of fruit or flower...

Jupiter, the fifth planet from the Sun and the largest in the solar system, is orbited by 69 moons, including lo, Europa, Ganymede, and Callisto. Europa, which is of the same size ...