Agriculture’s roots spread east to Iran

Agriculture originated across a broader swath of southwestern Asia’s Fertile Crescent, and over a longer time period, than many scientists have thought, excavations in western Iran suggest.

Between 11,700 and 9,800 years ago, residents of Chogha Golan, a settlement in the foothills of Iran’s Zagros Mountains, went from cultivating wild ancestors of modern crops to growing a form of domesticated wheat called emmer, say archaeobotanist Simone Riehl of the University of Tübingen, Germany, and her colleagues. Until now, most evidence of farming’s origins came from sites 700 to 1,500 kilometers west of Chogha Golan, the scientists report in the July 5 Science.

Unlike early farming villages that archaeologists previously unearthed in what are now Turkey, the West Bank, Syria and Iraq, Chogha Golan preserves a sequence of human occupations that provide a look at how agriculture developed over many centuries.

“The whole process, from cultivating wild precursor species to cultivating domesticated plants, took 1,000 to 2,000 years at Chogha Golan,” Riehl says.

Wild cereal cultivation began around the same time at sites extending east from the West Bank, Turkey, Syria and the Mediterranean island of Cyprus to Iraq and Iran, writes archaeobotanist George Willcox of Lumière University Lyon 2, France, in the same issue of Science.

But domestication of emmer occurred several hundred years later at Chogha Golan than at sites to its west, Willcox says.

Discoveries by Riehl’s team align with other recent evidence that various crops were gradually domesticated at sites across the Fertile Crescent, with the process proceeding more slowly in some areas than in others, Dorian Fuller of University College London says. Researchers traditionally thought that a rapid shift to farming occurred in the western Fertile Crescent.

In 2009 and 2010, Riehl’s team — which includes Iranian archaeologists — unearthed remains of 11 human occupations at Chogha Golan. The site’s first residents arrived around 12,000 years ago, the scientists say. Within a few hundred years, village inhabitants began cultivating wild plants including barley, wheat and lentil.

A spike in the proportion of distinctively shaped domesticated emmer wheat remnants appeared almost two millennia after wild wheat cultivation had started.

Increasing numbers of clay figurines, bone implements, stone grinding tools and stone vessels turned up at the Iranian site after 11,000 years ago, signaling an expanding population.

Agricultural knowledge may have spread from one or a few western farming centers eastward as far as Iran, either due to migration of crop-growing groups or to long-distance trading, Willcox says.

Riehl suspects, however, that people in at least a few areas — probably including western Iran — launched agriculture on their own. “There was no single core area where everything started, but rather regions where domestication of plant species began more or less independently.”

Editor’s Note: This story was updated on July 10 to correct the estimate of how much later domestication took place at Chogha Golan than at points west.