29 June 2009
Food storage began well before farming
People were storing grain long before they learned to domesticate crops, a new study indicates. A structure used as a food granary discovered in recent excavations in Jordan dates to about 11,300 years ago, according to a report in the Proceedings of the National Academy of Sciences. Yet much recent research suggests that plant domestication was preceded by a long period - perhaps thousands of years - during which prehistoric peoples cultivated wild plants without visibly changing their appearance or altering their genetic makeup. At the site of Gilgal 1, for example, near Jericho in the West Bank, excavators have found nearly 300,000 grains of wild barley and 120,000 grains of wild oats in a stone building dated to 11,400 years ago; smaller amounts of wild cereals have also been found at early villages in Israel, Jordan, Syria, and Turkey.
New discoveries near Gilgal 1 suggest that early farmers did not let these wild crops go to waste. Since 2002, a team led by archaeologists Ian Kuijt of the University of Notre Dame in Indiana and Bill Finlayson of the Council for British Research in the Levant in Amman, Jordan, has been excavating the site of Dhra', just east of the Dead Sea. Radiocarbon dating indicates that this village was occupied for a little more than 100 years beginning about 11,300 years ago. The excavators have uncovered at least 10 oval or circular buildings, with walls made of stone or mud bricks and mud floors, which appear to have been used both as houses and as food-processing centers. Interspersed between these units, the archaeologists have found at least four circular structures, about 3 meters in diameter, whose floors appear to have been suspended above the ground and which the team believes were granaries. Although analysis of plant remains found in these structures is still under way, they appear to have held wild barley, the team reports in the Proceedings of the National Academy of Sciences.
Inside the best preserved of these structures sits a series of notched stones set upright in the ground, which the archaeologists hypothesize supported wooden beams that were then covered with plants and mud to create a raised floor. This would have protected the grains from rodents and insects and also allowed for air circulation to keep them dry. The team argues that the storage of wild grains was essential to all of the key developments of the agricultural revolution: the emergence of domesticated cereals, the growth of large communities, and the rise of social hierarchies. Interestingly, the purported granaries at Dhra' were located outside of the village's residences and thus may have been shared by the entire community.
The ability to store food is essential for the development of farming, the researchers said. "The granaries represent a critical evolutionary shift in the relationship between people and plant foods, which precedes the emergence of domestication and large-scale sedentary communities by at least 1,000 years," they reported. Ehud Weiss, an archaeobotanist at Bar-Ilan University in Ramat-Gan, Israel, calls the new study "very interesting and persuasive" and concurs with the team's conclusion that the structures were probably granaries. Dorian Fuller, an archaeologist at University College London, agrees and adds that the timing of these earliest known granaries - which is at least contemporaneous with and possibly later than the earliest evidence for cultivation of wild plants - challenges the assumptions of some archaeologists that large-scale storage by hunter-gatherers was necessary before cultivation could begin.
Sources: ScienceNOW, Associated Press, Yahoo! News (22 June 2009)