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Primate archaeology: an evolutionary context for the emergence of technology

Final Report Summary - PRIMARCH (Primate archaeology: an evolutionary context for the emergence of technology)

The Primate Archaeology (PRIMARCH) project asked a simple but fundamental question: why do humans have such complex technologies when compared to other animals? This question can only be fully addressed by looking into the history of each species, the ways that they have developed over evolutionary timescales, and their relationships to the environment around them. With this in mind, the PRIMARCH project set out to investigate, for the first time, the archaeological record of multiple non-human animal species. With evolutionary questions in mind, it made sense to start with our closest relatives, the primates.

We conducted months of fieldwork with each of three primate species, bearded capuchin monkeys (Sapajus libidinosus), western chimpanzees (Pan troglodytes verus) and Burmese long-tailed macaques (Macaca fascicularis aurea). These are the only primates that are of known to use stone tools in the wild , which is important because stone tools survive archaeologically much better than sticks or leaf tools. Our fieldwork was based in northeastern Brazil, southeastern Guinea, the Ivory Coast, and southern Thailand, and we employed the same techniques of observation, survey and excavation in each site to allow us to compare results across species.

We found that the capuchins and macaques leave behind archaeological sites, which we were able to excavate and interpret just as we would a human occupation site. This discovery doubles the number of animals known to leave an archaeological record, and we showed that the capuchin activities dated back to before the arrival of Europeans in the New World. We also documented how these sites were created, as the macaques foraged for shellfish along island coasts and the capuchins used tools to break open cashew nuts and other fruits. The primates (including chimpanzees) selected suitable tools from the stones in their environment, then brought them to feeding places such as a fruit tree or large flat anvil stone. Each species mainly used stones to pound open foods, just as humans do with hard nuts today, but the capuchins also used them to dig in the ground and even as a means of getting another monkey’s attention.

One of our most significant discoveries was that wild capuchins at one site in Brazil pound stones directly against each other. This behaviour leaves behind debris that is quite similar to the sharp stone flakes made by early human ancestors, although in the case of the monkeys they were interested not in the flakes but in the quartz dust that the pounding produced. We still have a lot to understand about this behaviour, but at the very least we now know that making stone flakes can be no longer considered an exclusively human trait.

Equally as important as our findings, the PRIMARCH project successfully built and grew an international network of scholars interested in applying archaeology to their own research. This network has grown beyond primates to incorporate other wild tool-using animals such as crows and sea otters. We anticipate that one day, all animal tool use will be considered as a target for archaeological investigation, building up the same understanding of technological evolution for non-human species as we have for ourselves.