Plant processing and foodways in the Pastoral Neolithic: Microbotanical evidence from grinding stones at Luxmanda, Tanzania

Pastoralism has long been conceptualized as an animal-centered lifeway, with plants treated as marginal or ancillary resources. This is particularly true in Africa where rich ethnographic records of present-day pastoralism and scant archaeobotanical evidence have combined to create a focus on livestock in the archaeological record. This study challenges that perspective by demonstrating that plant use formed an integral component of Pastoral Neolithic (PN, c. 5000-1200 BP) practices in eastern Africa. Integrated phytolith and starch analyses were conducted on 44 residue samples from 33 grinding stones recovered at Luxmanda, Tanzania, the largest known PN settlement in eastern Africa, alongside sediment controls. Results indicate exploitation of a wide range of local plants, dominated by C 4 grasses – particularly panicoids – as well as wild rice, legumes, and geophytes. Starch grains point to the processing of grains/seeds and underground storage organs, while the low frequency of inflorescence phytoliths suggests that grinding stones were not primarily used for cereal dehusking and may reflect the processing of already-cleaned grains or non-food activities. The predominance of leaf and culm phytoliths highlights the multifunctional roles that plants can play in pastoral contexts, including technological and medicinal practices. Plants were actively integrated into subsistence strategies, daily practices, and resource management in the PN. These findings constitute a critical first step towards understanding complex relationships between plant use and the long-term success of pastoralist food systems in eastern Africa, and hold broader implications for pastoralist studies worldwide.