BRIA 18 4 a Environmental Disasters in the Cradles of Civilization

Archaeologists have evidence that small hunting and gathering groups in many parts of the world set forest and prairie fires to get rid of unwanted vegetation. Hunters also used fires to flush out game. These fires often changed plant and animal habitats in ways that favored food resources most beneficial to humans.

Hunters in North America drove herds of buffalo over cliffs to their death. But the hunters could use the meat of only a few of the dead animals, which sometimes numbered in the thousands. In some places, over-hunting caused the extinction of some animals and birds. "These first American settlers," says one environmental historian, "left a trail of destruction across the continent."

After thousands of years of constantly moving in search of food, the people in a few isolated areas of the world began to settle favorable areas. These people could do this only when they learned how to cultivate food crops and domesticate animals. Beginning about 10,000 years ago, this agricultural revolution was probably the most important human invention of all time.

Farming allowed people to live in the same place for long periods of time. After planting, it gave people more time to focus on art, religion, and architecture. In time, it led to cities, labor specialization, class systems, and more leisure time. Civilizations could not have developed without the invention of agriculture.

Agriculture and the Environment

At first, farming required more work than hunting and gathering. But agriculture had one big advantage. Growing crops and raising animals on a limited area of land could sustain a larger population, which made a group more powerful. Once people understood this, they began to construct permanent homes. This eventually led to cities and all the other things that define a civilization.

The first agricultural settlements of 50 to 100 persons emerged primarily in hilly areas of Southwest Asia. These areas today make up Jordan, Israel, Lebanon, Syria, southern Turkey, and western Iran. The climate consisted of long dry summers and short rainy winters. The soil was naturally fertile, but thin. The world's first farmers cultivated grains like wheat and barley along with some vegetables. They domesticated mainly sheep and goats.

As the village populations grew, farmers cleared more land for planting. They burned forests and plowed up the groundcover. In the meantime, their herds of sheep and goats increased, requiring more land to graze. Goats in particular are very efficient grazers, eating weeds and other plants of little use to people.

As more people settled in villages, they constructed houses and other buildings, often with wood. They also used wood as a fuel for cooking, heating, and burning lime to make plaster.

By about 6000 B.C., they had eliminated most of the forests around their villages. In addition, much of the natural groundcover was gone due to grazing by goats and intense farming. The dry climate required a long time for trees, other natural vegetation, and the soil to regenerate. With ever more mouths to feed, however, the farmers could not wait. They could not afford to let the land remain fallow (unplanted) for more than a year or two.

Finally, the winter rains began to erode the thin bare soil, ruining the land for farming. Farmers cleared new lands, but the same cycle of deforestation, erosion, and ruined land took place. Gradually, food production decreased. The population dropped. Sometimes, people abandoned entire villages.

The Sumerian Puzzle

The Tigris and Euphrates rivers begin in the mountains of Turkey and flow south for more than a thousand miles through modern-day Iraq to the Persian Gulf. Known in ancient times as Mesopotamia, the lands between these two rivers lacked adequate rainfall for agriculture. But people could always use water from the rivers for their crops.

By 5000 B.C., many small farming villages flourished near the banks of the two great rivers. The farmers dug simple ditches to irrigate their fields of wheat, barley, and vegetables. The resulting increase in the food supply led to a population explosion.

Several hundred years later, independent city-states like Ur arose. They had populations ranging from 10,000 to 50,000 people. By 3000 B.C., the city-states of southern Mesopotamia had formed the world's first civilization, called Sumer.

The Sumerians developed a complex class system that included priests, rulers, a government bureaucracy, craft workers, merchants, laborers, soldiers, and peasants who worked the fields. The rulers organized major building projects in the cities. They constructed canals for a large irrigation system that opened more land for growing food crops. The Sumerians also developed the world's first writing system.

In the early 20th century, archaeologists in Mesopotamia puzzled over the barren desert that had once been a rich and powerful civilization. "What happened to Sumer?" they asked themselves.

Over the centuries, silt carried by the Tigris and Euphrates built up the stream beds. Eventually, the surrounding farmlands were below the level of the rivers. The Sumerians constructed levees to contain the rivers, which worked except during major floods.

The irrigated water went to the fields, where it often collected on the surface. The hot Mesopotamian sun evaporated the standing water and left behind layers of salt. The soil also became waterlogged in places. This caused the water table to rise, bringing more salt to the surface. One clay tablet with Sumerian writing recorded that "the earth turned white."

The only solution to this salt problem, called salinization, was for the Sumerians to leave the land unwatered and fallow for several seasons to allow the water table to fall. The scarce rains would then slowly draw the salt down below the soil cultivation zone.

The Sumerian farmers knew that leaving the land alone for a while was the right thing to do. But the rulers of Sumer had based their wealth and power on the skills and labor of an ever-growing population. Therefore, they ordered the farmers to continue irrigating and planting the damaged land to produce more food.

Wheat is less tolerant of salt than barley. Based on clay tablet records, barley gradually replaced wheat in the Sumerian diet. Soon, the yields of barley and the other crops decreased steadily. The Sumerian people began to suffer from hunger, which led to malnutrition and disease.

The shortsighted demands of the Sumerian rulers led to the collapse of their civilization. The rulers could no longer feed and pay for large armies. Peasant revolts and warfare among the Sumerian city-states erupted over control of remaining fertile farmlands. Finally, in 2370 B.C., the Akkadian Empire from the north conquered a weakened Sumer.

By 1800 B.C., agriculture in southern Mesopotamia had almost disappeared, leaving an impoverished people who lived on a desolate and poisoned land. The world's first civilization had created a monumental environmental disaster.

Short-Term Gains and Long-Term Consequences

The pattern of shortsighted treatment of the environment continued in most of the other cradles of civilization. In the Indus River Valley of India, another rich society based on irrigation agriculture arose around 2300 B.C.

Once again, a vast irrigation system caused soil salinization. In addition, the people constructed their buildings with kiln-fired bricks. The kilns required huge amounts of wood to fuel the firing process. Within a few hundred years, the people had cleared the hillside forests, causing severe erosion of the farmlands in the valley below. By 1900 B.C., the people of the Indus River Valley civilization had abandoned their once-impressive cities.

In China, farmers in the northern plains plowed the grasslands to plant millet, another grain crop. But wind and rain soon eroded the soil. Massive deforestation also added to the erosion disaster. For centuries afterward, silt from the erosion clogged Chinese rivers, causing frequent destructive floods and the loss of millions of lives.

One of the major cradles of civilization avoided an environmental crisis for more than 7,000 years. Egypt's Nile River floods annually, washing away any salt deposits and laying down new fertile soil. This natural cycle enabled Egyptian farmers to sustain high crop yields year after year.

In modern times, Egypt built dams on the Nile to control the floods and hold reserves of water. But the dams also blocked the fertile silt from reaching the farmlands and replenishing the soil. Today, Egyptian agriculture depends heavily on expensive commercial fertilizers.

Most ancient environmental disasters occurred because of the salinization or erosion of farmlands caused by irrigation systems, deforestation, and overgrazing by domesticated animals. In these ways, the Persians, Greeks, Romans, Vikings in Greenland, Mayans in Central America, Native Americans in the Southwest, and Polynesians on Pacific islands all damaged their environments to some degree.

Climate changes and warfare often added pressure on civilizations already weakened by environmental disasters. In virtually every case, however, people contributed to their own downfall by over-exploiting their environment for short-term gains while ignoring the long-term consequences.

For Discussion and Writing

  1. Why was the invention of agriculture necessary before any world civilization could develop?

  2. Why do you think most hunting and gathering peoples gave up their old ways to become farmers?

  3. What were the main causes of environmental disasters in ancient civilizations? Why do you think these disasters repeatedly occurred all over the world?

For Further Information


Prehistoric People A short explanation and links to many sites on prehistory. From 4 2 explore.

Diet and Subsistence Articles on hunting and gathering, pastoralism, and agriculture. From Prehistoric Puzzles, Indiana University.

Development of Agriculture

Neolithic Agriculture: The Slow Birth of Agriculture An article by Heather Pringle in Science.

The Agriculture Revolution A simple explanation. From Idea Works.

Agriculture And The Origins Of Civilization: The Neolithic Revolution From Ragz-International.

Agriculture Revolution From Washington State University.

Agriculture and Husbandry From Lynn H. Nelson, Department of History, University of Kansas.

Agriculture and Pastoralism Links from


Collapse--Mesopotamia From Annenberg/CPB.

Sumeria Links to information. From Chrystalinks.

Ancient Sumer History From History of the Ancient Near East Electronic Compendium.

Other Disasters

Environmental History Timeline: Ancient Civilizations

History of Use and Abuse An excerpt from Linking People and Ecosystems by World Resources Institute.


A Green History of the World By Clive Ponting.

Review: Peace and Environment News

Human Impact on Ancient Environments By Charles L. Redman.

Review: H-Net Review

Ecology in Ancient Civilizations By Donald J. Hughes.

Review: Bryn Mawr Classical Review


Long-Term Impacts From Short-Term Gains

In this activity, students discuss and report on questions related to modern environmental problems.

Form small groups to discuss the following questions:

1. What long-term negative impacts on the American environment could result from the following short-term gains?

A. Depending more on irrigated farmlands in areas with little rainfall.

B. Increasing logging and road construction in forests.

C. Building more single-family home housing developments.

D. Manufacturing more and larger gasoline-powered vehicles.

2. What measures can you recommend to avoid the negative impacts you have identified without endangering the economy of the country?

After discussing these questions, each group should report its conclusions to the class.


Diamond, Jared. "Lessons from Lost Worlds." Time. 26 Aug. 2002:A54-A55. • Hughes, J. Donald. Ecology in Ancient Civilizations. Albuquerque, N.M.: University of New Mexico Press, 1975. • Kluger, Jeffrey and Dorfman, Andrea. "The Challenges We Face." Time. 26 Aug. 2002:A7-A12. • Ponting, Clive. A Green History of the World. New York: St. Martin's Press, 1991. • Redman, Charles L. Human Impact on Ancient Environments. Tucson, Ariz.: University of Arizona Press, 1999.



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