Agriculture: Amid discoveries in Israel, scientists rethink theories on the transition from hunter-gatherer in the Fertile Crescent.

Medicine & Science

August 16, 2004|By Dennis O'Brien | Dennis O'Brien,SUN STAFF

A key step in our evolution from cave to condo - right up there with taming fire and inventing the wheel - was the transition from hunter-gatherer to farmer.

It enabled people to settle, build villages and establish cultures, crafts and kingdoms.

"Agriculture was the first human attempt to master our ecology, and it became a package - a lifestyle that would take over the world and lead to everything we have," said Gordon Hillman, a researcher at University College London.

Decades of digging by archaeologists show that farming probably began at least 13,000 years ago in the Fertile Crescent, an arc-shaped swath in the Middle East that runs north from Israel through Lebanon, east through southern Turkey and south to the Persian Gulf.

But a series of discoveries in Israel, announced this summer, is prompting scientists to rethink popular theories about how quickly the transition occurred in the Fertile Crescent. A pair of studies of microscopic grains of grass and cereal found at an ancient settlement near the Sea of Galilee show that people were gathering wild grains much earlier than previously thought, indicating that the shift to farming took at least 10,000 years.

"It means people were well adapted to these grassy environments and using them as resources before they began cultivating any crops, for a long, long time," said Dorian Fuller, an archaeobotanist also at University College London. "It changes the way we view this whole transition."

Plant remains

Harvard researchers reported in Proceedings of the National Academy of Sciences last month that 90,000 plant remains found at the site, known as Ohalo II, show that people ate wild grains 23,000 years ago - 10,000 years earlier than previously recognized.

In a second study, scientists say a dinner-plate-sized grinding stone from the site shows that people 23,000 years ago were also grinding up the grains they ate, including wild emmer wheat, barley and other cereals.

Grains wedged into the stone show that it was used to grind grain, the earliest evidence found of cereal processing. Such a tool is a significant advance because it shows that people began to manipulate their diets, said Dolores R. Piperno, the Smithsonian archaeobotanist who was lead author on the study, published Aug. 5 in Nature.

"In processing, you reduce the particle size, remove the fiber and make the fibers more nutritious," she said. "It's a major step forward."

Botanists date grains and seeds using the same carbon-14 dating methods as geologists, and Ohalo turned out to be a treasure trove: Thousands of grains were preserved because the area was inundated by the sea until droughts caused the site to resurface.

"Because it was inundated, it was covered over by water, and so it's very well preserved by lake sediments that washed over the area," Piperno said. "The site is remarkable for the quality of what's preserved."

`Slow process'

The shift from gathering to farming is often called the Neolithic Revolution, a term coined in the 1940s to describe the changes created by the advent of agriculture. But experts say the findings show that the transition was not a revolution, but a more gradual and complicated process.

"We used to ask, `How could this have happened so quickly?' Now, we're faced with the question, `How could this have taken so long,'" said Bruce Winterhaler, an anthropologist and expert on hunter-gatherer societies at the University of California, Davis. "We see it's a slow process; it's taking tens of thousands of years."

Farming developed later in different parts of the world, experts say. Evidence shows that the Chinese started growing rice and millet roughly 11,000 years ago. Tribes in what is now Mexico may have cultivated maize, or corn, as far back as 9,000 years ago.

But for decades, the Fertile Crescent has been identified as farming's birthplace. In 1997, Norwegian researchers determined that 68 lines of cultivated einkorn wheat grown in the foothills of Turkey's Karadag Mountains were genetically similar to species domesticated in the region about 11,000 years ago.

Experts say the Fertile Crescent was likely to have attracted farming because of its fertile soils, range of elevations, and mix of rainfall and temperate weather.

But Hillman, the University College London researcher, says climate and population growth also played a role. His studies of grains found in ancient villages along the Euphrates River show that hunter-gatherers turned to farming when their populations grew, climates became harsh and the wild grains began to disappear.

Hillman said a group of hunter-gatherers established the first of three settlements found along the Euphrates River, known as Abu Hureyra, about 13,500 years ago, at the end of the last Ice Age. They were attracted by the wild cereals - rye, lentils and einkorn wheat - produced by steady rains and temperate conditions.

"People settled here when climate conditions were optimum. There was steady rainfall, and it produced these wild cereals and grasses that were more than enough," Hillman said.

But about 500 years after they arrived, there was a drought and "one by one, their major food plants disappeared," Hillman said. They began planting wild rye and wild wheat.

"It's the earliest evidence we have so far of hunter-gatherers cultivating grain," he said.

Archaeologists remain puzzled about why people began farming in some areas, while at other sites, they apparently moved away without planting anything. Of dozens of archaeological sites studied in the Fertile Crescent, only a handful show signs of developing into an agricultural community, Fuller said.

"Some people stay put and try to tough it out, while others move on. The question is, why does that happen?" Fuller said.

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