Organic matter from bevelled rim bowls of the Middle Euphrates: Results from molecular characterization using pyrolysis-GC-MS

The Middle and Late Uruk period (3600-3100 BCE) is characterised by the diffusion of the Uruk culture in Mesopotamia and surroundings. Uruk sites are recognised by a special kind of pottery called bevelled rim bowls (BRBs), which comprise up to 80% of all recovered Uruk pottery. BRBs are very basic, handmade bowls produced in large quantities but their function is still under debate. Several uses have been proposed, including cooking, measurement of cereal rations, bread preparation, salt making or as votive bowls. Searching for evidence that supports the proposed hypotheses we studied BRB samples from several archaeological sites in the Middle Euphrates (Syria). We analysed fragments of pottery by pyrolysis coupled to gas chromatography and mass spectrometry (Py-GC-MS) to identify organic molecules that could be related to past BRB contents. Additionally, we cooked bread in experimentally produced BRBs to compare results. Up to 93 organic compounds could be identified, including polysaccharides, lignin products and fatty acids. The unequivocal presence of lignocellulose residues (especially 4-vinylguaiacol and other guaiacols, which were also found in experimentally charred bread heated below 450 °C), is compatible with the proposed hypothesis of leavened bread cooking, but a source of incomplete burn off of organic temper cannot be discarded.