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.
Third, primate archaeologists can excavate long-abandoned primate tool use sites. In the Ivory Coast, there is an archaeological site called Panda 100, which some researchers believe is a chimpanzee stone tool site. This site is over 4,000 years old, suggesting that chimpanzees have been using tools for much longer than researchers have been observing in the wild.
Primate archaeology allows us to infer how our ancestors used tools. The last common ancestor between humans and chimpanzees split into two lineages approximately 6 million years ago. Australopithecines are one of our oldest ancestors that archaeologists believed used tools. They lived about 2-3 million years ago in eastern and southern Africa. With the exception of upright walking, australopithecines still looked quite similar to chimpanzees, and even lived in similar environments as the savanna chimpanzees in Uganda.
Studying chimpanzee tool use in the wild can provide archaeologists with information about what sort of tools they should be examining further in the archaeological record. For example, researchers are currently working in the petrified forest of Sibiloi National Park in Kenya where they are searching for fossilized wood that may share similar marks with modern wood used as anvils at chimpanzee nut-cracking sites. Additionally, research with Kanzi and the other bonobos he lives with at the Ape Cognition and Conservation Initiative is ongoing, and the tools he produces can be compared to the archaeological record to investigate both the physical skills and cognitive abilities of our early ancestors.