Searching for hidden activities: Percussive tools from the Oldowan and Acheulean of West Turkana, Kenya (2.3-1.76 Ma)

Over the last thirty years, investigations in the Nachukui Formation (West Turkana, Kenya) have revealed the importance of the region for human evolution studies within an archaeological sequence spanning the period 3.3 million years (Ma) to 0.7 Ma. Despite the numerous sites discovered, little is known about pounding activities during this time period in the region. In this paper, we present an analysis of percussive tools from three West Turkana archaeological sites: Lokalalei 2C, Kokiselei 1 and Kokiselei 4, dated between 2.3 Ma and 1.76 Ma. Their chronological range allows us to conduct a diachronic comparison of the percussive activities during a time span with two hominin genera (Australopithecus boisei, early Homo and Homo erectus). The three assemblages are compared with others from the Early Stone Age and with experimental percussive tools. Despite the stable predominance of hammerstones associated with stone knapping activities over time in the Nachukui Formation, our macroand microscopic analyses reveal an inter-site variability in the type and re-use of percussive tools for specific heavy-duty pounding activities. When compared with other Early Stone Age sites, Lokalalei 2C, Kokiselei 1 and Kokiselei 4 similarly present a low frequency of pounding tools but a high number of blanks used for both flaking and pounding activities, suggesting that the reutilization of the tools and the change in their functionality was common in the ESA lithic record.