A civilization is an organized group of people living with laws, culture, a way to get food and ways to protect themselves. The word is derived from the Latin civis, meaning “citizen.” Historians, anthropologists and archaeologists may differ on whether a particular human society meets the definition of civilization or even whether it should be categorized as such. In a broad sense, any complex human society that has advanced enough to be able to live with a reasonable degree of comfort and security can be considered a civilization.
The earliest civilizations developed in places where people could farm and the crops provided more than enough food to support a larger group of people. The ability to grow enough food allowed people to work on other tasks, such as specialized trades, crafts and military defense. As the population grew people began to build cities, develop more sophisticated forms of religion and create political structures.
Civilizations first appeared in places that were suitable for agriculture, such as river valleys. This is because early hunter-gatherers generally gravitated toward fresh water, as it is a key ingredient for life. Later, humans developed farming techniques that allowed them to produce a surplus of food. This made it possible to eat what was grown and also sell excess food for money or goods. This in turn led to a greater variety of specialized jobs and the development of higher levels of social stratification.
Early human cultures developed around the world, in Mesopotamia and Egypt in what is now the Middle East, in the Indus Valley of what is now Pakistan and India, in ancient China along the Huang He (Yellow River) valley, and in Central America. All of these civilizations had a number of features in common, such as highly stratified societies with several inherited classes including kings, nobles, freemen and slaves, cities and advanced forms of religion.
Most of these civilizations also had a form of writing that enabled people to communicate with each other more effectively and to store information for future use. Writing took many forms, from the cuneiform glyphs of ancient Mesopotamia to ideograms and hieroglyphs in Egypt and elsewhere in the ancient world. In some cases, such as with oracle bone inscriptions in ancient China and quipu-knotted strings used by the Inca empire of South America, writing served to record and communicate religious texts.
The development of agriculture, urbanization and more sophisticated forms of religion and government helped to bring these early civilizations together into what we think of as a single “civilized” world. But there are a number of reasons why these and other ancient civilizations eventually collapsed. Jared Diamond, for example, has suggested that civilizations achieve a maximum level of complexity that is sustainable and then decline once they exceed this limit. Other reasons that have been proposed include environmental damage; the need to engage in long-distance trade for critical resources; political upheaval; and societal responses to natural disasters such as war or drought.