Modern thermoplastic (hot glue) versus organic-based adhesives and haft bond failure rate in experimental prehistoric ballistics

The prehistoric production of composite technologies throughout human evolution was facilitated greatly by the use of adhesives. One such technology was projectile weaponry, which used adhesive to attach a stone point to a wooden shaft. Prehistoric projectile weaponry is often studied via experimental archaeology, which recreates ancient technologies to understand their manufacture and function. Here, we explore whether a modern thermoplastic adhesive can serve as a suitable replacement for two organic adhesives that would have been used by past peoples – pine rosin and hide glue – in modern experimental tests of prehistoric weaponry. We conducted a ballistics experiment and shot groups of stone-tipped arrows, each group hafted with one of the three adhesives, and assessed the haft bond failure rate. The modern thermoplastic adhesive was similar to that of the pine rosin and significantly failed less often than the hide glue. We conclude that in some cases modern thermoplastic adhesive can be substituted for organic-based adhesives in experimental archaeology. Our results also show that hafting bond failure rate was significantly different between the pine rosin and the hide glue, suggesting that prehistoric hunter-gatherers faced costs or benefits in selecting adhesives for hafting.