Grinding what?: Using tribology, microscopic use-wear patterns and context to understand ancient foodways in northern Ethiopia 1600 BCE – 800 CE

Grinding stones were significant tools used in foodways for millennia across the globe. Though these tools have received little attention in the past, within the last few decades there is an increasing interest in studying grinding stones to learn more about the people of the past. Theoretically this research was grounded in practice theory, reconnecting the tools with the people who use/used them. Many methods contributed to this research to achieve a more holistic understanding of grinding stones and their place in the lives of people of the past and present in Gulo Makeda, northeastern Tigrai, Ethiopia. It was through ethnoarchaeology, and then confirmed by experimentation, that there is a preference for different surface textures to process large versus small sized cereal grains. Experimentation combined with ethnoarchaeological data aided in building models of grinding stone manufacture, use and discard. Use-wear analysis allowed for interpretations of tool function and use. It is through the application of tribological principles that use-wear was observed and classified under 'adhesive', 'abrasive', 'fatigue', and 'tribochemical' wear. Microscopic use-wear images indicate a visual difference between coarse and smooth surfaces, allowing for identification of texture type through a more quantitative means than simply tactile analysis. Use-wear analyses revealed artifacts that were originally misclassified as grinding tools. During analyses, methodological issues also arose and recommendations to move the study of use-wear on ground stone tools forward have been included. A focus on context of recovery informed interpretations of grinding/ground stone tools and the use of spaces. The contextual analysis also brought to light possible changes in foodways between the Pre-Aksumite 1600 BCE – CE 1, and the early state development of the Aksumite period CE 1 – 800. More crops were added, there may have been specialized grinding by the Aksumite period and there is evidence for specialized craftsmanship at Ona Adi. It is clear that grinding stones can shed light on the past practices of ancient people.