Archaeological Adhesives Made from Document Innovative Potential in the African Middle Stone Age

Studying the earliest archaeological adhesives has implications for our understanding of human cognition. In southern Africa, the oldest adhesives were made by in the Middle Stone Age. Chemical studies have shown that these adhesives were made from a local conifer of the family. However, does not exude resin, nor any other substance that could have been recognized as having adhesive properties. Therefore, it remains unknown how these adhesives were made. This study investigates how adhesives can be made, comparing their mechanical properties with other naturally available adhesives. We found that tar can only be made by dry distillation of leaves, requiring innovative potential, skill, and knowledge. This contrasts with our finding that the Middle Stone Age environment was rich in substances that can be used as adhesives without such transformation. The apparent preference for tar may be explained by its mechanical properties. We found it to be superior to all other substances in terms of its adhesive properties. In addition, the condensation method that allows producing it can be recognized accidentally, as the processes take place above ground and can be triggered accidentally. Our findings have implications for establishing a link between technology and cognition in the Middle Stone Age.