from about 10,000 to 6000 BC. My favorite exception, the dog, was brought into the human fold more than twenty thousand years earlier. I can easily imagine the scenario in which a young wolf or orphaned puppies would submit to human rule and join a pack of human hunters. Watching dogs run in Seattle's off-leash parks, I see how hunters could use dogs as partners in the hunt, especially the ones that habitually turn prey back toward the pack. In any case, dogs were not domesticated for direct consumption. There is no evidence that early people ate their first animal allies. Instead, dogs increased human hunting efficiency and probably served as sentries in early hunting camps. (Cats were relative latecomers, as they moved into agricultural settlements roughly four thousand years ago, soon after towns first overlapped with their range. As people settled their habitat, cats faced a simple choice: starve, go somewhere else, or find food in the towns. No doubt early farmers appreciated cats less for their social skills than for their ability to catch the small mammals that ate stored grain.)
Sheep were domesticated for direct consumption and economic exploitation sometime around 8000 BC, several hundred years before domestication of wheat and barley. Goats were domesticated at about the same time in the Zagros Mountains of western Iran. It is possible that seeds for the earliest of these crops were gathered to grow livestock fodder.
Cattle were first domesticated in Greece or the Balkans about 6000 B.C. They rapidly spread into the Middle East and across Europe. A revolutionary merger of farming and animal husbandry began when cattle reached the growing agricultural civilizations of Mesopotamia. With the development of the plow, cattle both worked and fertilized the fields. Conscription of animal labor increased agricultural productivity and allowed human populations to grow dramatically. Livestock provided labor that freed part of the agricultural population from fieldwork.
The contemporaneous development of crop production and animal husbandry reinforced each other; both allowed more food to be produced. Sheep and cattle turn parts of plants we can't eat into milk and meat. Domesticated livestock not only added their labor to increase harvests, their manure helped replenish soil nutrients taken up by crops. The additional crops then fed more animals that produced more manure and led in turn to greater harvests that fed more people. Employing ox power, a single farmer could grow far more food than needed to feed a family. Invention of the plow revolutionized human civilization and transformed Earth's surface.
There were about four million people on Earth when Europe's glaciers melted. During the next five thousand years, the world's population grew by another million. Once agricultural societies developed, humanity began to double every thousand years, reaching perhaps as many as two hundred million by the time of Christ. Two thousand years later, millions of square miles of cultivated land support almost six and a half billion people—5 to 10 percent of all the people who ever lived, over a thousand times more folks than were around at the end of the last glaciation.
The new lifestyle of cultivating wheat and barley and keeping domesticated sheep spread to central Asia and the valley of the Nile River. The same system spread to Europe. Archaeological records show that between 6300 and 4800 BC adoption of agriculture spread steadily west through Turkey, into Greece, and up the Balkans at an average pace of about half a mile per year. Other than cattle, plants and animals that form the basis for European agriculture came from the Middle East.
The first farmers relied on rainfall to water their crops on upland fields. They were so successful that by about 5000 BC the human population occupied virtually the entire area of the Middle East suitable for dryland farming. The pressure to produce more food intensified because population growth kept pace with increasing food production. This, in turn, increased pressure to extract more food from the land. Not long after the first communities settled into an agricultural lifestyle, the impact of top-soil erosion and degraded soil fertility—caused by intensive agriculture and goat grazing—began to undermine crop yields. As a direct result, around 6000 BC whole villages in central Jordan were abandoned.
When upland erosion and the growing population in the Zagros Mountains pushed agricultural communities into lowlands with inadequate rainfall to grow crops, the urgent need to cultivate these increasingly marginal areas led to a major revolution in agricultural methods: irrigation. Once farmers moved into the northern portion of the floodplain between the Tigris and Euphrates rivers and began irrigating their crops, they reaped bigger harvests. Digging and maintaining canals to water their fields, settlements spread south along the floodplain, sandwiched between the Arabian Desert and semiarid mountains poorly suited for agriculture. As the population rose, small towns filled in the landscape, plowing and planting more of the great floodplain.
Figure 4. Early Mesopotamian representation of a plow from a cylinder seal (drawn from the photo of a cylinder seal rolling in Dominique Collon, First Impressions: Cylinder Seals in the Ancient Near East [Chicago: University of Chicago Press, 1987], 146, fig. 616).
This narrow strip of exceptionally fertile land produced bumper crops. But the surpluses depended upon building, maintaining, and operating the network of canals that watered the fields. Keeping the system going required both technical expertise and considerable organizational control, spawning the inseparable twins of bureaucracy and government. By about 5000 BC people with a relatively common culture in which a religious elite oversaw food production and distribution populated nearly all of Mesopotamia—the land between two rivers.
All the good, fertile land in Mesopotamia was under cultivation by 4500 BC. There was nowhere else to expand once agriculture reached the coast. Running out of new land only intensified efforts to increase food production and keep pace with the growing population. About the time the whole floodplain came under cultivation, the plow appeared on the Sumerian plains near the Persian Gulf: it allowed greater food production from land already farmed.
Towns began to coalesce into cities. The town of Uruk (Erech) absorbed the surrounding villages and grew to about 50,000 people by 3000 BC. Construction of huge temples attests to the ability of religious leaders to marshal labor. In this initial burst of urbanization, eight major cities dominated the southern Mesopotamian region of Sumer. The population crowding into the irrigated floodplain was now a sizable proportion of humanity. Whereas hunting and gathering groups generally regarded resources as owned by and available to all, the new agricultural era permitted an unequal ownership of land and food. The first nonfarmers had appeared.
Class distinctions began to develop once everyone no longer had to work the fields in order to eat. The emergence of religious and political classes that oversaw the distribution of food and resources led to development of administrative systems to collect food from farmers and redistribute it to other segments of society. Increasing specialization following the emergence of social classes eventually led to the development of states and governments. With surplus food, a society could feed priests, soldiers, and administrators, and eventually artists, musicians, and scholars. To this day, the amount of surplus food available to nonfarmers sets the level to which other segments of society can develop.
The earliest known writing, cuneiform indentations baked into clay tablets, comes from Uruk. Dating from about 3000 BC, thousands of such tablets refer to agricultural matters and food allocation; many deal with food rationing. Writing helped a diversifying society manage food production and distribution, as population kept pace with food production right from the start of the agricultural era.
Rivalries between cities grew along with their populations. The organization of militias reflects the concentration of wealth that militarized Mesopotamian society. Huge walls with defensive towers sprang up around cities. A six-mile-long wall circling Uruk spread fifteen feet thick. Wars between Sumerian city-states gave rise to secular military rulers who crowned themselves as the governing authority. As the new rulers appropriated land from the temples and large estates became concentrated in the hands of influential families and hereditary rulers, the concept of private property was born.
The
