Putting ochre to the test: replication studies of adhesives that may have been used for hafting tools in the Middle Stone Age.

Substantial frequencies of Middle Stone Age (MSA) lithics from Rose Cottage and Sibudu Caves in South Africa have red ochre on their proximal and medial portions. Residue studies suggest that the tools were hafted and that the ochre may be part of the adhesive used for hafting the tools. Replication studies show that ochre is indeed a useful loading agent for adhesive; however, there are other potential loading agents. It is also possible to use unloaded plant resin, but this agent is brittle and difficult to work with. It appears that people living in the MSA had wide knowledge of ingredients suitable for hafting tools, and that they chose different adhesive recipes because of the required properties of the adhesive. Brittle, unloaded adhesive allows a projectile head to disengage its haft and implant itself in an animal; robust adhesive keeps a spearhead safely in its shaft.