University of Warsaw, Poland.

Long-term British excavations at Tell Brak unearthed remains of a large early city that already in the beginning of the 4th millennium BCE covered at least 120 hectares. At the outskirts of this urban centre, a small mound called Tell Majnuna appeared to be a midden that was used in the first half of the 4th millennium, filled with pottery sherds, animal bones and sealings, but also with many human elements that were buried in more or less regular clusters. Most skeletons were incomplete, but some anatomical connections still present, accompanied by massive evidence of scavenging by carnivorous mammals. The minimum number of individuals in all test trenches, which covered less than 5% of the site volume, was estimated as more than 200. To understand the cause of mass mortality in the city and obvious abandonment of regular burial rites, research on short-term climate changes has been undertaken using oxygen-18 values in human enamel as a proxy for temperature. Selected canines with still ongoing root formation were sectioned and the oxygen isotope values measured with the Sensitive High-Resolution IonMicroprobe (SHRIMP II) in c. 100 spots per tooth covering subsequent enamel incremental layers, allowing reconstruction of climate history in c. 7 years prior to death of selected individuals. In all teeth clear increase of oxygen-18 values was observed in the enamel that was formed c. 3-4 years before death and this feature was accompanied by pronounced linear enamel hypoplasia indicating that the mass mortality could be the consequence of a prolonged drought affecting inhabitants of an overpopulated city located in the area where agriculture was risky due to relatively low and unpredictable annual precipitation.