A rich trove of artifacts and plant remains excavated from southwestern Iran suggest that ancient humans’ transition from hunting and gathering to farming occurred throughout the Fertile Crescent at roughly the same time.
The excavation also revealed that this crucial change — which helped the region earn its reputation as the cradle of civilization — happened gradually over thousands of years, not in a few generations or centuries as previously thought, according to a study published Thursday in the journal Science.
The findings from the excavation in the foothills of the Zagros Mountains represent a paradigm shift in scholars’ understanding of agriculture’s origins, and the villages, towns and civilizations that emerged as a result, experts said.
For decades, archaeologists believed agriculture took root in a part of the Fertile Crescent called the Levant, which includes present-day Israel, Lebanon and Jordan, as well as parts of Syria, Iraq, Saudi Arabia and other countries. From there, it was thought to have spread eastward to present-day Iran.
“The eastern Fertile Crescent has been treated as backwater,” said Melinda Zeder, a senior scientist at the Smithsonian Institute’s Program in Human Ecology and Archaeobiology, who was not involved in the study. Now, the understanding that people in the Zagros grew and ground cereal grains as early as their counterparts in the Levant has “democratized this situation where everyone in the region was involved,” she said.
Excavations in the western Fertile Crescent yielded evidence of plant and animal domestication dating to about 11,500 years ago, while digs in the eastern Fertile Crescent found evidence of domestication dating to only about 9,500 years ago. However, after the Iranian Revolution in 1979, Western archaeologists were unable to analyze sites in the east with the same modern recovery and dating techniques used to study those to the west.
Improved diplomatic relations between Iran and the West enabled archaeologists from the University of Tuebingen in Germany to visit the 12,000-year-old site of Chogha Golan in 2009 and 2010, which they excavated with their counterparts from the Iranian Center for Archaeological Research. They were eager to do so, since recent genetic analysis of modern-day barley and animals such as sheep, pigs and goats in the eastern Fertile Crescent suggested that domestication could have begun earlier than 9,500 years ago.
The items they unearthed from the 7-acre site were remarkably well-preserved. Perched at the edge of a former looter’s pit, the archaeologists drew up 10-liter buckets filled with botanic and stone remains. They rinsed off the sediment and discovered human and animal figurines, fish bones and charred bits of wild barley, lentil, grass peas, emmer wheat and other ancestors of crop plants.
“I’ve never seen a site so rich,” said Nicholas Conard, an archaeologist at the University of Tuebingen and co-author of the study.
The archaeologists also discovered chaff remains from cereal grains, indicating that people processed their harvest. They also found mortars and grinding stones, which may have been used for turning the grain into flour or bulgur, which resembles rice.
The findings at Chogha Golan also indicate the transition from foraging to farming was a long, gradual process.
As ancient people began domesticating wild plants by nurturing the ones with the traits they liked best, they attracted certain kinds of weeds that thrived in cultivated land. Finding large numbers of these weeds among the ancestors of crop plants is “a signature of cultivation,” Zeder said.
Archaeologists observed this signature at Chogha Golan and calculated that these weeds grew around 11,500 years ago. But it wasn’t until more than 1,000 years later that wild food plants took on their recognizable domesticated shape.
While the study makes a convincing case that agriculture emerged at about the same time in many parts of the Fertile Crescent, it still isn’t clear why the region was so well-suited to the development of farming.
Zeder thinks abundant resources meant that people didn’t have to travel far to find food and could settle in one place. That allowed them to develop ways of protecting valuable resources and increasing their bounty.
How agriculture spread throughout the Fertile Crescent — whether by the communication of ideas, migration of people or spread of crops — also remains a mystery, the study authors wrote.
Conard and his colleagues still have hundreds of samples left to analyze. Eventually, the team plans to continue excavations at Chogha Golan to learn more about its inhabitants, including their social structure, said Simone Riehl, an archaeobotanist at the University of Tuebingen and the study’s lead author.