The oldest Earth rocks known to date, found in Quebec, Canada in 2008， were determined to be about 4.3 billion years old. However, the oldest known materials of the solar system-M...

  During the European Renaissance (1300-1600)， artists in Florence, Italy, made striking use of oil-based paints, but the development of these paints was part of a long and c...

Molt is the process in which birds shed feathers and replace them by growing new ones. It is a costly effort that typically follows breeding in the warmest months of the year and p...

  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...