“We focused on seal imagery that originated before the invention of writing, while continuing to develop into the proto-literate period,” study co-authors Kathryn Kelley and Mattia Cartolano, both researchers in the Department of Classical Philology and Italian Studies at the University of Bologna, said in a statement. The study draws attention to several motifs found on preliterate cylinder seals, which the authors suggest later evolved into proto-cuneiform signs on 5,000-year-old clay tablets from Uruk in southern Mesopotamia. University of Pennsylvania archaeologist Holly Pittman, who was not involved in the study, told Live Science in an email that the new research supports her theory from about 30 years ago: that the imagery on seals significantly influenced proto-cuneiform writing.