As scholars have debated the definition of civilization, they have come to agree on some characteristics that civilizations tend to share. These include food surpluses, higher population densities, social stratification, systems of taxation, labor specialization, regular trade, and accumulated learning. The list is by no means complete, but it indicates the complexity of societies that historians have labeled civilized.
Civilization requires complex societies to organize themselves, and these societies often take shape as cities, where people clustered together for work, worship, and play. The earliest cities were nexuses of power, production, and culture, and they also demanded a high level of human labor. Officials gathered taxes, engineers planned irrigation schemes, and soldiers defended city walls. Farmers worked the land, and artisans specialized in basketry, carpentry, or metalwork. Even religious leaders needed to take part in a variety of activities, from attending public rituals to settling disputes and leading armies.
To support such a complex society, food had to be produced in larger quantities than hunter-gatherers could manage. As farming grew, a new class of upper-class people developed, consisting of priests, government officials, and warriors who controlled the agricultural wealth of the lower classes. This elite group, along with the kings and rulers of the lower classes, gained a degree of political and religious authority unmatched in earlier tribal societies.
In addition to producing food, early cities required extensive manipulation of the environment to extract resources like firewood, building materials such as stone, and water for drinking and irrigation. These practices were a significant cause of climate change, which made floods and droughts more common, and increased the risk of disease and conflict among densely populated cities.
Despite these challenges, urban civilizations continued to develop. As agriculture became more advanced, it allowed for the cultivation of crops such as barley and wheat. This, in turn, fueled the development of trade with regions far away, bringing new foods, raw materials, and ideas to cities that would have otherwise been isolated.
As urban civilizations developed, the need for specialized workers led to the creation of professions. In early times, many of these were based on skills acquired through training by family members. But the need for more skilled workers encouraged people to move from villages to towns, where jobs were available.
At the same time, war and trade brought other people’s buildings and items into contact with those of urban civilizations, which spurred on the development of more sophisticated technologies. This is one of the reasons that scholars have argued that civilizations need not be confined to the world’s continents. Nonetheless, scholars are still making judgments about which cultures meet the criteria for civilization. Some of these judgments are rooted in racial and religious prejudice, but others are made with the best intentions. Some scholars have questioned whether some modern day countries meet the criteria for being considered a true civilization. These include India and China, which have developed advanced industrial and technological capabilities while still maintaining ancient traditions of Hindu or Buddhist faith and racial equality.