INVENTING AGRICULTURE

SEEDS OF DOMESTICATION

GENETIC CHANGES

THANK THE FARMER

SCANDINAVIAN SCENE

GONE FISHING

Farmers in Senegal use wind to winnow (separate) peanuts from chaff. Peanuts were domesticated across the Atlantic Ocean, on Brazil's coast.
© David Tenenbaum.

Between 11,500 and 10,000 years BP, agriculture moved out from the Levant to the rest of the Fertile Crescent.
Courtesy Ofer Bar-Yosef.

Moving toward agriculture
If necessity is the mother of invention, then hunger was the mother of agriculture. That's the word from Ofer Bar-Yosef, an Israeli archeologist now at Harvard University who's spent his career studying the origin of agriculture in the Middle East. He thinks a cooling trend caused a decline in food availability, which induced our forebears to start sowing and harvesting wheat and other cereal crops.

Bar-Yosef calls himself a "climate determinist" and says he's long believed climate helped shape agriculture. (Let's define agriculture as the domestication and cultivation of plants or animals, encompassing growing fruits, vegetables and birds, mammals and fish. And let's note that not everybody agrees with Bar-Yosef's analysis.)

Bar-Yosef has focused on the Natufian culture, which was present in the Middle East between 15,000 and 11,000 years before present (BP). Among other distinctions, Natufians occupied the ancient city of Jericho. Bar-Yosef says the early Natufians, who lived between 15,000 and 13,000 BP, were sedentary.

No, they didn't watch the tube 24/7 -- they lived year-round in villages, indicating that they presumably didn't need to truck far for food. Archeologists recognize the villages of sedentary people not by the hulks of prehistoric televisions but by skeletons of free-loading animals like rats and mice, and by too-heavy-to-lug-around objects like food-grinding stones.

Moving around
Around 13,000 BP, after two millennia of hanging close to the hearth, the Natufians began spending part of the year away from their villages. Why? Bar-Yosef notes that the change coincided with a cool, dry interruption in the global warm-up that ended the ice age. The so-called "Younger Dryas" period is known from reliable climate records from ice cores from Greenland.

During the Younger Dryas, forests in the Natufian region retreated, leaving open woodlands. The cool, dry conditions made traditional foods, including wild relatives of wheat and barley, harder to find, forcing the Natufians to leave home and resume their semi-sedentary lifestyle. The "stable, sedentary structure collapsed, people begin moving around the Levant," says Bar-Yosef, who has excavated several Natufian villages.

The more accurate dates available from Greenland have, shall we say, plowed under the idea that agriculture arose throughout the Fertile Crescent, according to Bar-Yosef. He thinks domestication actually occurred in the Levant -- the western end of the Crescent -- because domesticable wild grains were absent from the rest of the area during the Younger Dryas. Carbonized plant remains show that the essential wild relatives were present only in modern Israel, Syria and Turkey.

Narrowing the field
At one of those villages, Netiv Hagdud, near Jericho, shells and bones show that the carnivorous side of the hunter-gatherer menu listed mollusks and crabs, moles, eels, ducks and frogs. The vegetarian menu listed more than 50 wild plants, including wild legumes, figs, pistachios and acorns. Significantly, charred seeds found at the site showed that the people also ate wild wheat and barley.

Bar-Yosef says that at a small Natufian community like Netiv Hagdud, wheat and rye were first domesticated about 11,500 years ago, during the Younger Dryas: "The beginning of cultivation emerged from an environment of stress that forced people to rely more heavily on cultivated species. The Natufians, seeing the depletion of natural fields, came to the conclusion that they should start planting them instead of harvesting in the wild."

The archeological evidence for domestication includes remains of cereal grains found near cooking fires, stone sickles used to harvest grains, and pounding stones for removing the inedible chaff from the edible kernel.

How can you distinguish wild rice from Uncle Ben's?