Reconstruction of environment in early Bronze Age Syria through phytolith analysis on human dental calculus

"Aridification leading to crop failure has recently been hypothesized to explain the collapse of the Akkadian Empire in ancient Mesopotamia (~2300 and 2200 B.C.). Phytoliths from the dental calculus of 17 human skeletons excavated from Tell Leian in northern Syria were investigated to test whether a change in floral dietary resources accompanied site abandonment. Multicelled phytoliths from Period III individuals (3000-240.0 B.C.) were larger and more abundant than those from Period VI (5000-4100 B.C.) and Period II (2400-2200 B.C.) individuals. This increase in silicification during Period III signals the presence of humid growing conditions, while smaller phytoliths and reduced abundance during Period VI, and especially Period II, indicate that and conditions prevailed. One adult female in Period III possessed remarkably large multicelled phytoliths; she probably had access to the irrigated cultigens grown in Southern Mesopotamia. Phytolith evidence supports the aridification hypothesis for the abandonmentof Tell Leilan at 2200 B.C."