A framework for how Neandertals may have evolved the ability to produce tar is described in a study in Scientific Reports.
The manufacture and use of adhesives for hafting - the process of attaching bone or stone to a handle to create weapons or tools - has become a focal point in the debate about the cognitive and technological capabilities of Neandertals and early modern humans. Adhesives are one of the earliest transformative technologies known and tar production is at least 200,000 years old. However, it is unclear how tar was produced during the Pleistocene (approximately 2,588,000 to 11,700 years ago) without the use of ceramic containers. Previous experimental attempts at tar manufacture using aceramic or Palaeolithic technology have resulted in a tar yield too small for the effective hafting of tools.
Paul Kozowyk and colleagues carried out tests of the dry distillation of birch bark to produce tar using variations on potential Palaeolithic techniques. The authors found that tar could be produced using aceramic technology compatible with a Neandertal context and that a bark roll in hot ashes could produce enough tar to haft a small tool. Repeating this process several times would have produced the quantities seen in the archaeological record. The authors propose a framework for how the production of tar may have evolved, with changes to the production process that would have improved tar yield efficiency, and consistent with the technology and resources available to Neandertals during the Middle Palaeolithic.
Further investigation of the composition and nature of tar lumps may help to refine the history of the development of tar technology.