Dirt. David R. Montgomery
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The earliest evidence for systematic cultivation of grains comes from Abu Hureyra in the headwaters of the Euphrates River in modern Syria. The archaeological record from this site shows that cultivation began in response to a period when the drier conditions of glacial times abruptly returned after thousands of years of climatic amelioration. Abu Hureyra provides a unique record of the transition from the hunter-gathering lifestyle of the last glacial era to cereal-based agriculture. Moreover, evidence from the site helps explain why people adopted the labor-intensive business of agriculture. They were forced into it.
As glaciation ended, the Levant gradually warmed and received increasing rainfall. From about 13,000 to 11,000 BC open oak forest gradually replaced the grasslands of the glacial steppe. A core drilled from the bed of Lake Huleh in northeastern Israel shows that tree pollen increased from a fifth to three-quarters of all the pollen during this period. Abundant game and wild grains (especially rye and wheat) made for an edenic landscape with few people and lots of resources. Sedentary communities of hunter-gatherers began to take root in locations where resources were particularly abundant.
Then the world's climate reverted to almost full glacial conditions for a thousand years, from about 10,000 to 9000 BC, a period known as the Younger Dryas. Arboreal pollen dropped back to less than a quarter of the total amount of pollen, indicating a sharp decline in precipitation and a return to the steppelike conditions of the glacial climate. The forest retreated northward, away from the world's first settled community.
Abu Hureyra sat on a low promontory overlooking the Euphrates Valley, about 180 miles northeast of Damascus. Plant debris excavated from the site records the transition from foraging for a wide variety of wild plants to cultivation of a few crops by the end of the Younger Dryas. The earliest plant remains associated with settlement of the site include more than one hundred species of seeds and fruits from the marshes and forest of the Euphrates Valley. Abundant animal bones reveal substantial reliance on hunting, especially gazelles. Moreover, the site was occupied year-round. The people of Abu Hureyra were not nomadic hunter-gatherers. They permanently inhabited a defined territory around their village. A couple hundred people occupied Abu Hureyra by the time that the Younger Dryas ushered in a thousand years of cold, dry weather that dramatically altered plant and animal resources. Fruits and seeds of drought-sensitive plants disappeared from the diet. Wild lentils and legumes harvested from nearby woodland also disappeared. As eden dried out, food became scarce.
Why didn't they just move? Probably because Abu Hureyra was already one of the region's best sites. Surrounding areas experienced similar changes and offered even less sustenance. Besides, other people already occupied the next best land. People with rapidly disappearing food supplies usually do not welcome new neighbors. The people of Abu Hureyra had no place to go.
Out of options, they began to cultivate wild varieties of rye and wheat that survived the transition to a colder, more arid climate. Of the plants that survived, only cereals could be cultivated to produce food capable of storage for use throughout the year. Despite the worsening aridity, seeds of drought-intolerant weeds typical of agricultural fields increased dramatically during the Younger Dryas. At first, wild cereals were cultivated on hillsides using rain-fed agriculture. Within a few centuries domesticated varieties of rye appeared in the fields, as did legumes such as lentils.
The switch to cultivation required more time and energy to produce a calorie of food. It is not something that would have been undertaken lightly. The sedentary style of hunting and gathering practiced by the early inhabitants of Abu Hureyra left them susceptible to declining food availability as the climate changed. Once wild food sources were fully exploited the population was vulnerable to seasonal shortages brought on by increasing aridity. Begun out of desperation, agriculture expanded to include other crops such as barley and peas as the climate improved after the Younger Dryas ended. Settlement around Abu Hureyra grew rapidly in the warmer climate. Fueled by growing harvests, within a couple thousand years the village's population swelled to between four thousand and six thousand.
Figure 3. Map of the Middle East.
The climate shift of the Younger Dryas was not the only factor that influenced the adoption of agriculture. Population growth during the preceding several thousand years led to the advent of sedentary communities of hunter-gatherers and contributed to the effect of this climate shift on human populations. Still, the starving people of Abu Hureyra could never have imagined that their attempt to adapt to a drying world would transform the planet.
Such adaptation may have occurred around the region. The end of the Younger Dryas coincides with changes in culture and settlement patterns throughout much of the Middle East. Neolithic settlements that emerged after the Younger Dryas were located at sites ideally suited for agriculture with rich soils and ample water supplies. Charred remains of domesticated wheat dating from 10,000 years ago are found in sites near Damascus, in northwestern Jordan, and on the Middle Euphrates River. Domesticated crops then spread south to Jericho in the Jordan Valley and northwest into southern Turkey.
Although tradition places agriculture in the Middle East long before any parallel activity in Asia and the Americas, recent research suggests that people in South America, Mexico, and China may have domesticated plants long before the first signs of settled villages in these regions. Sediments in a cave called Diaotonghuan along China's Yangtze River tell a story similar to that of Abu Hureyra in which wild rice was domesticated around the time of the Younger Dryas. Perhaps the abrupt climate changes of the Younger Dryas pushed semisettled people with declining resource bases into agricultural experimentation.
Once the climate improved, groups adapted to growing grains had an advantage. Increasing reliance on domesticated crops spread across the region. The Natufian culture that flourished along the Mediterranean coast in modern Israel, Lebanon, and Syria from 9000 until 7500 BC was based on harvesting wild grain and herding goats and gazelles. Neither plants nor animals were fully domesticated when Natufian culture arose, yet by the end of the era, hunting accounted for just a fraction of the food supply.
The regional population began to grow dramatically as domestication of wheat and legumes increased food production. By about 7000 BC small farming villages were scattered throughout the region. Communities became increasingly sedentary as intensive exploitation of small areas discouraged continuing the annual cycle of moving among hunting camps scattered around a large territory. By about 6500 BC large towns of up to several thousand people became common. The seasonal rhythm of an annual trek to follow resources was over in the Middle East.
Populations able to wrest more food from their environment could better survive periods of stress—like droughts or extreme cold. When bad times came, as they inevitably did, chance favored groups with experience tending gardens. They better endured hardships and prospered during good times. And agricultural success upped the ante. Development of more intensive and effective subsistence methods allowed human populations to grow beyond what could be supported by hunting and gathering. Eventually, communities came to depend on enhancing the productivity of natural ecosystems just to stay even, let alone grow. Early cultivators became tied to a place because mobility did not allow for tending and harvesting crops. Once humanity started down the agricultural road there was no turning back.
Learning to support more people on less land once they settled into a region, farmers could always marshal greater numbers to defeat foragers in contests over territory. As their numbers grew farmers became unbeatable on their own turf. Field by field, farms expanded to cover as much of the land as could be worked with the technology of the day.
Most farm animals were domesticated