More than 1,000 years before humans began domesticating grains for food, they were building sophisticated storage buildings to hold the wild grains they were cultivating, researchers reported Monday.
Collecting large quantities of grains and other foods is a prerequisite to establishing sizable communities, but such collection requires a system to store the perishables so they can be kept for months at least. The new find reported in the Proceedings of the National Academy of Sciences represents the oldest known storage system or granary to date -- about 11,300 years old.
The earliest known domestication of cereal grains was thought to have occurred about 10,500 years ago.
Four granaries were discovered in the settlement of Dhra' near the Dead Sea in what is now Jordan by archaeologists Ian Kuijt of the University of Notre Dame and Bill Finlayson of the Council for British Research in the Levant in Amman, Jordan. The granaries were among 10 buildings found at the village, which was occupied for about 100 years. The other buildings appear to have been used as dwellings and food processing sites.
The oval buildings, about 9 feet in diameter and 9 feet high, had mud floors and walls of stone and mud bricks.
The best preserved granary shows unusually sophisticated engineering. Notched stones set upright in the floor of the building, about 1 to 1 1/2 feet high, presumably supported wooden beams, which spanned the structure. These beams were then covered with plants and mud to create a raised floor that enabled air to circulate through the stored grains, keeping them dry. The raised floor also protected the food from rodents.
Dating indicates that the original granary was used for about 50 years, then a second granary was built on its remains and also used for half a century. Traces of wild barley were found in the building.
The granaries were presumably shared by the entire village. The communal sharing did not persist, however. Excavations at later sites in the region show that storage shifted to individual dwellings.
"The most important implication of our findings," the scientists wrote, "is that fundamental social changes occurred before plant domestication, including the establishment of fairly permanent settlements with communal labor and storage, based on cultivated wild plants."