Experts continue search for origins of agriculture

Dolores Piperno, an archaeobotanist with the Smithsonian Tropical Institute, wrote in the June 22 issue of Science that the search for the origins of agriculture is equivalent to the fabled quest for the Holy Grail. Most of us take the vegetables on supermarket shelves for granted and never give a thought to the fact that some enterprising individuals in the far distant past took wild plants and slowly turned them into a reliable food source.

But curiosity about when and where this came about existed as far back as the ancient Greeks, according to Heather Pringle in the Nov. 20, 1998, issue of Science. Agriculture was credited to Demeter, the goddess of crops, who crisscrossed the Earth in a chariot pulled by dragons sowing wheat and other seeds while bestowing the dual blessings of agriculture and civilization. At least the latter part of this myth has been generally accepted as true by present-day scientists.

Conventional wisdom has it that agriculture arose in the Near East and was accompanied by the gathering together of nomadic foragers into the first settlements. A trio of Israeli scientists gives support to the first part of this theory in the June 2, 2000, issue of Science. They disagree with the “where” part of the theory, which is generally given as being areas of what is now Israel and Jordan, saying a more likely region is a small swath of the Fertile Crescent near the upper reaches of the Tigris and Euphrates rivers in what is now Syria and Iraq.

Beryl Simpson and Molly Ogorzaly agree with this assessment in their book, “Plants in Our World.” The Israelis give the “when” as about 10,000 BP (before the present). Pringle agrees with this date and goes on to indicate that hunter-gatherers settled in small communities after the last Ice Age and swiftly learned to sustain themselves by breeding better grains and other plants. She says this improved way of life set the world down the path to civilization as it diffused outward across the Old World.

Wild strains of several important food crops, including wheat, barley, lentils, flax and chickpeas, are known to have had their origins in the Fertile Crescent and archaeological evidence of their domestication lends weight to the popular theory. But is it true?

Research into ancient farming employs a combination of traditional archaeological and modern techniques. In the April 27 issue of Science, Kathryn Brown lists among the former such diverse clues as food residues stuck to unearthed tools, teeth and pottery shards to the search for undigested grain kernels in human coprolite. Today, there has been added such high-tech tools as mass spectrometry, carbon dating and genetic fingerprinting.

The results of research of the past decade or so have called the traditional view of agriculture’s birth into question. Piperno writes that archaeologists now believe that farming arose independently in six to eight regions of the world including both hemispheres of the Americas. Pringle agrees in principle but points out that the Fertile Crescent may still have had an edge in cultivating cereal grains. Seeds of cultivated rye that have been carbon dated to 13,000 BP have been found in Syria, making them the oldest known domesticated cereal grain in the world.

The other truism that seems not to be so true is that settlements arose concurrently with, or even preceded, the cultivation of plants. In her review of the birth of agriculture, Pringle states, “It no longer makes sense to suppose a strong causal link [exists] between farming and settled village life.”

Bruce Smith of the Smithsonian Institution gives the now generally accepted lag times between the cultivation of crops and establishment of settlements in the March 13, 1998, issue of Science. These are 3,000 years in the Near East, between 4,000 and 6,000 years in the Americas, and similar extremely long lag times in other parts of the world such as China.

Smith says the long periods of time between settlements and established domesticated crops are because of the existence of “in-between species” that were being gathered for food but still had not been cultivated long enough to be identifiable as either wild or fully domesticated species.

Agriculture in the Americas varied with the crops. Corn or maize, the staple usually associated with American Indians, was a relative latecomer, as Piperno says the earliest evidence for its cultivation is 7,100-year-old maize pollen found on the tropical coast of Mexico. By contrast, Warwick Bray, in the Nov. 9, 2000, issue of Nature, reports that arrowroot was cultivated in the region of Colombia around 9000 BP and Bruce Smith, in the May 9, 1997, issue of Science, that squash was domesticated in Oaxaca, Mexico, over 10,000 years ago. He says that squash, as a domestic plant, predates maize and beans by more than 4,000 years. This assertion may be premature because Bray says that a layer of charcoal and plant fragments found in Panama, and dating to 11,000 years ago, may indeed represent early slash and burn farming.

Jeffrey Bendremer and Robert Dewar, in a contributed chapter in the book “Corn and Culture in the Prehistoric New World,” give estimates of plant domestication in New England ranging from 500 B.C. to A.D. 1400 depending on location. The authors believe maize arrived in New England no later than A.D. 1000 and it is certain that maize, beans, squash and possibly sunflowers were well-established crops when Europeans arrived on these shores.

Clair Wood taught chemistry and physics for more than 10 years at Eastern Maine Technical College.