Researchers have discovered numerous chimpanzee stone tools for breaking various kinds of nuts

Early in 2022, while conducting fieldwork in the Taï Forest in Cote d'Ivoire,the researchers discovered and 3D-scanned a range of stone tools.

The usage of wooden and stone tools differs among different chimpanzee groups, as has long been demonstrated. But only a few populations of chimpanzees in West Africa utilize stone tools to split open nuts. A recent study presented in the Royal Society Open Science

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journal demonstrates that there are significant differences between two groups in terms of their material culture by contrasting the 3D models of various stone tools used by chimpanzees in the Taï Forest to those from another group in Guinea.

Female chimpanzee cracking Panda oleosa nuts using a granodiorite hammerstone on a wooden (panda tree root) anvil. Credit: © Liran Samuni, Taï Chimpanzee Project

Specifically, the research demonstrates that this particular group of chimpanzees in Guinea employs enormous stone anvils, some of which can measure more than one meter in length, as well as stone hammers of various types and sizes. These robust stone tools are widely distributed throughout the environment; they preserve varying degrees of wear and tear from their use and serve as a permanent record of chimpanzee habits.

Examples of chimpanzee hammerstones from Djouroutou, Cote d’Ivoire; illustrating their textured surface, three-dimensional surface, surface depth and surface gradient. Credit: © Tomos Proffitt

This study also emphasizes how, despite the fact that different chimpanzee groups engage in nut cracking, the tools they employ can vary greatly, possibly producing group-specific material signatures. These variations are caused by a combination of the nut species consumed, stone preference, and stone accessibility.

Lead author, Tomos Proffitt from the Max Planck Institute of Evolutionary Anthropology, says,

“The ability to identify regional differences in stone tool material culture in primates opens up a range of possibilities for future primate archaeological studies. By understanding what this simple stone tool technology looks like, and how it varies between groups, we can start to understand how to better identify this signature in the earliest hominin archaeological record."

Previous studies have demonstrated that some chimpanzee populations create their own archaeological record that dates back at least 4,300 years by using stone tools. It has been proposed that during the early phases of our own evolution more than three million years ago, a straightforward technique, such as nut-cracking, served as a predecessor to more sophisticated stone technologies.

1. Proffitt, T., Reeves, J. S., Pacome, S. S., & Luncz, L. V. (2022). Identifying functional and regional differences in chimpanzee stone tool technology. Royal Society Open Science, 9(9), 220826. https://doi.org/10.1098/rsos.220826