Use-wear and residue analysis of pounding tools used by wild capuchin monkeys (Sapajus libidinosus) from Serra da Capivara (Piaui, Brazil)

Bearded capuchin monkeys (Sapajus libidinosus) from Serra da Capivara National Park (Brazil), perform the widest range of activities using stone tools of all the non-human tool-using primates. The behaviours behind this range of tool-use have been closely documented, but little is known about the characteristics of the tools themselves. Here we redress this imbalance and adopt an archaeological perspective to the analysis of capuchin pounding tools. We apply, for the first time, systematic microscopic techniques to the analysis of capuchin stone tools used for digging, cracking cashew nuts and seed processing to characterise their damage patterns combined with residue spatial distribution and micro-remains analysis. This work presents a standardized methodology for future primate archaeological use-wear studies as well as forming a reference collection which can be used to identify different activities within the primate archaeological record. Furthermore, understanding the archaeologically visible traces of primate percussive behaviours represents an initial step in developing a methodology to investigate if similar activities were practiced by early hominins and to help identify these activities in the Plio-Pleistocene archaeological record.