Back to the Stone Age: Why study primate archaeology?

This is the first installment of the Primate Conversation Series. You can read parts two and three here!

In 1960, Jane Goodall observed a chimpanzee, whom she named David Greybeard, deep in the Tanzanian jungle using a stick to fish for termites. This discovery was the first documented observation of a chimpanzee using tools in the wild and quashed the long-held view that humans are unique in their ability to make and use tools. Although many other animals, including all great ape species, have since been observed using tools, our closest living relatives, the chimpanzees (Pan troglodytes), are by far the most adept non-human species at making and using tools in the wild. Chimpanzees have been observed using over 40 different tool types in their repertoire, including tools for feeding behaviors, grooming, comfort, protection, socialization, and even curiosity. Therefore, they are the most widely studied tool-using species, both in the wild and captivity. In recent years, researchers have started exploring how studies of primate tool use can help us learn about ourselves and our extinct ancestors.

Archaeology has been used for over a century to study our ancestors by unearthing the tools and civilizations they left behind and experimenting with modern recreations to learn about how those tools may have worked. Specifically, primate archaeologists apply three main methods to study primate tool use.

First, scientists can study tool use in the wild. They may incorporate a variety of techniques such as observing what materials primates use to perform different functions like Jane Goodall did with David Greybeard or excavating a recent tool use site to determine why chimpanzees chose specific materials to make tools. For example, nut-cracking sites can be found by looking at the marks left on rocks that nut shells leave once they have been heavily used (the empty nut shells lying around also help with identification). In some cases, chimpanzees will use hard pieces of wood or tree roots as anvils, or hard surfaces that holding the nut in place as they smash it, and this action can also leave behind marks on the wood. In contrast, termite-fishing sites are a bit easier to identify since they are located near termite mounds. Chimpanzees use sticks, stems, or twigs from nearby trees as fishing tools. These tools become easier to identify when they have been modified in some way, like being stripped down to enable animals to reach into the mounds.

Second, scientists can study tool use in captive settings. This methodological approach can provide information about a primate’s cognitive abilities by allowing researchers to introduce primates to new scenarios that would not normally occur in their natural habitat. This sort of research is even happening locally in Indiana at the Indianapolis Zoo! Tool use in captivity is not just for research purposes, but also provides enrichment to keep the animals minds’ active, to challenge them, and to prevent boredom. One of the most famous examples of captive primate archaeology studies is of the bonobo (Pan paniscus) Kanzi being taught how to flintknap, or make stone tools.