Food Production

Theories of Farming Origins

Victorian scientists believed agriculture was a brilliant inventions¸ fostered by a rare genius. One day¸ went the scenario¸ a solitary forager was carrying home a bundle of edible grasses when she stumbled spilling some of her load on damp ground. A few days later¸ she passed the same way and noticed small green shoots sprouting from the soil. With startling insight¸ the women realized the potential of her new invention¸ planted more seeds near her hut¸ and fed her family off the bountiful harvest. Other families soon copied her example and agriculture was born.

Such captivating scenarios offer simple explanations¸ but have no foundations in scientific fact. First¸ no one ever “invented” agriculture¸ because all hunters–gathers knew that grasses germinated each year. Root crops like African yam can be propagated simply by cutting off the top placing it in the soil. Foragers living on the fringes of the African rainforest as early as 40¸000 years ago may have planted yams in that way¸ but such practices are a far cry from the cultivation of cereal grasses¸ which began in Old World and New after the Ice Age. Reality was more complex than mere invention and is still little understood.

Nor did a single society “invent” agriculture¸ for farming appeared at widely different times in many parts of the world. Farmers in southwestern Asia´s Euphrates and Jordan River Valleys cultivated wheat and barley by about 8¸000 B.C.E. Central American cultivators grew domesticated squashes by about the same date. Chinese villagers harvested rice by 6¸000 B.C.E.¸ perhaps earlier. Most scientists believe that a set of complex cultural and environmental factors combined with populations growth to cause societies in widely separated parts of the world to shift from foraging to food production¸ usually within a relatively short time¸ sometimes a few generations.

At the end of the Ice Age¸ foragers in drought–prone subtropical zones such as southwestern Asia and highland Mesoamerica were exploiting potentially domesticable wild grasses and root plants with greater intensity. Dependence on such foods probably came earlier in these regions¸ where there were only a few forageable plant food. Such dependence was essential to long–term survival and led almost inevitably to experimentation with deliberate planting of wild cereals and ultimately to cultivation. In contrast¸ population in more humid plant rich regions¸ like Africa and Amazonian rainforest¸ probably did little more than plant a few wild species to minimize risk of starvation in lean years long after farming appeared in more temperate regions. Cereal agriculture came to tropical Africa only within the past 3¸000 years¸ and it spread widely after the introduction of iron technology some centuries later.

During the 1920s¸ University of Chicago Egyptologist Henry Breasted popularized the term Fertile Crescent to describe the cradle of agriculture and civilization in southwestern Asia. The Crescent has its arms in Mesopotamia and the Nile Valley¸ joined by a great arch across the Jordan Valley and Zagros Mountains of Iran. The label has fallen into disuse in recent years¸ but is apt in the sense that it spans the vast arc of contrasting terrain where agriculture¸ and urban civilization¸ first began. Most speculation about agricultural origins has surrounded the Fertile Crescent.

Early Theories: Oases and Hilly Flanks

Gordon Childes Agricultural Revolution offers a good starting point for it was the first modern attempt to explain agricultural origins. Drought conditions formed the core of his revolution thesis. He speculated that after Ice Age the southwestern Asian climate became increasingly dry forcing both animals and humans to concentrate in areas like the Jordan Valley where permanent water supplies were available and plant foods perennially abundant. The arid conditions brought animals¸ humans¸ and plants into a close symbiosis (Greek ¦ “life together”)¸ creating favorable conditions for foragers to experiment with cereal grasses and with herding wild goats and sheep. These experiments revolutionized human existence and spread rapidly throughout southwestern Asia and further afield.

Childe proposed the Agricultural Revolution long before pollen analysis¸ deep sea cores¸ and other highly sophisticated tools for climatic reconstruction were applied to Asian sites. The theory was simple but unproven. During the 1950´s¸ University of Chicago archaeologist Robert Braidwood took a multidisciplinary team of botanists¸ geologists¸ and zoologists on a major field expedition to the Zagros Mountains what he called the “hilly flanks” of southwestern Asia. he recovered the first climatic data for Holocene times and found evidence of increased forest cover and high rainfall after the Ice Age. He also excavated early farming settlements high above the fertile lowlands which at the time¸ were considered exceptionally early as they radiocarbon dated to about 6¸000 B.C.E.

Braidwood rejected Childe´s oasis theory and argued that agriculture and animal domestication began in the mountainous terrain at the periphery of fertile lands. Higher rainfall meant more wild food supplies and denser game populations in the lowlands. Highland people were not so fortunate and adopted agriculture to increase food supplies in the face of rising populations. In other words agriculture began on the flanks¸ not in the center.

The Recovery Revolution

Braidwood and Childe theorized at a time when multidisciplinary research was still in its infancy. Since the 1950's archaeology has gone through what one may call a “recovery revolution¸” a dramatic refinement of field and laboratory methods that has produced infinitely more fine grained data. The recovery revolution has taken place alongside other important developments ¦

Multidisciplinary studies of Holocene climate change¸ which combine pollen samples from lakes and marshes with deep sea and tree–ring data to produce a chronicle of large–and small–climate change since 10¸000 B.C.E. These data allow archaeologists to place early farming sites within much more precise environmental contexts.
A mass of new botanical data acquired through systematic use of flotation methods which allow the recovery of large samples of wild and domesticated seeds from occupation levels.
Major advances in zooarchaeology¸ the study of animal bones¸ have a provided a wealth of new information on the domestication of cattle¸ goats¸ pigs¸ sheep¸ and other animals.
Accelerator mass spectrometry (AMS) radiocarbon dating permits the dating of individual seeds root fragments or maize cobs. For the first time we can date early farming with high precision as opposed to merely dating layers in which tiny seeds are found (and into which they may have fallen from higher levels).

The past 20 years have seen the development of more sophisticated ecological interoperations of the origins of food production which result in large part from much larger data bases of archaeological and environmental data.

Science

Flotation and Botanical Remains

Until the 1960s archaeologists knew little of early domesticated plants. They lacked a recovery technology to excavate more than a few handfuls of carbonized seeds preserved in storage pits or hearths. Flotation methods¸ first developed in the North America Midwest¸ revolutionized our knowledge of ancient farming. By passing soil samples through water or chemicals¸ today´s excavators can recover thousands of seeds¸ as they float to the surface while the heavier soil matrix sinks to the bottom of the screen. Elaborate flotation machines can process dozens of samples an hour. The sample is poured into a screened container and agitated by water pouring into the screen. The light plant materials float on the water and are carried out of the container by a sluice–way that leads to fine mesh screens¸ where the seeds are trapped and wrapped in fine cloth for further study. Flotation is rewriting the early history of both foraging and farming. Botanist Gordon Hillman has reconstructed the foraging habits of 16¸000–year–old hunter–gatherers living alongside the Nile River during the last Ice Age. His studies of the environment at Abu Hureyra¸ Syria¸ described in the next section¸ document how tree cover receded from the site as drought became endemic. The inhabitants responded by gathering wild grasses¸ then cultivating them to amplify their food supply. Flotation has also been extensively in eastern North America¸ the South–west and the Andean area¸ with similarly dramatic results.