Food or fibercraft? Grinding stones and Aboriginal use of Triodia grass (spinifex)

Plant tissue and wooden objects are rare in the Australian archaeological record but distinctive stone tools such as grinding stones and ground-edge hatchets are relatively common, and they provide strong indirect evidence for plant food processing and woodworking, respectively. Ethnohistorical references to the Aboriginal use of stone tools for technologies related to fibercraft, basketry, hafting adhesives and fixative sealants (with gum, wax and resin) are also rare but all these tasks were probably more common than records indicate. Here we consider ethnohistorical evidence for stones in fibercraft and the processing of Triodia grass (spinifex) as a case study. We compare functional traces on experimental stones with traces on a museum specimen (CMAA 1926.591), which was collected ethnohistorically and reportedly used for 'grinding spinifex leaves'. Residues and other traces on the museum specimen are consistent with both fiber-processing and seed grinding. We suggest that it may be difficult for usewear and residue analysis to determine if grinding stones were used to target Triodia spinifex for fiber, food or another particular plant product. Further experimental research is needed to refine criteria for identifying archaeological fiber-processing tools. However, we propose that the combination of traces previously interpreted as seed processing on bedrock grinding patches and portable grinding stones may also indicate the processing of Triodia spinifex for fiber.