Chimpanzees are well known for their tool use, from nut-cracking with stones to using sticks for termite fishing. But new research suggests they do more than just grab the nearest twig—they appear to engineer their tools by selecting materials with specific mechanical properties.
A study published in iScience1 by Alejandra Pascual-Garrido and colleagues explores how chimpanzees at Gombe Stream National Park in Tanzania choose plant materials for termite fishing probes. Their findings indicate that chimpanzees consistently select flexible materials, likely because these make more effective tools for extracting termites from twisting tunnels.
“This is the first comprehensive evidence that wild chimpanzees select tool materials based on specific mechanical properties,” explains Pascual-Garrido.
Why Flexibility Matters
Termites provide a rich source of protein, but getting to them requires a precise technique. The insects build intricate networks of tunnels inside mounds, and stiff tools would have trouble navigating these spaces. The researchers hypothesized that chimpanzees prefer more flexible tools because they can bend into these passages rather than breaking or getting stuck.
To test this, the team measured the stiffness and flexibility of different plant materials used by the chimpanzees and compared them to available but unused plant species. Their findings were striking—plants used for tools were 175% more flexible than those that were ignored.
Material Selection: A Sign of Higher Cognition?
Chimpanzees’ preference for certain plants isn’t random. The study found that even among plants growing near termite mounds, the ones that showed signs of repeated use produced more flexible probes than those that weren’t used.
This suggests that chimpanzees recognize which materials work best, possibly through experience or social learning.
“Chimpanzee toolmaking mechanics may inform on the technical skills of early hominins,” the researchers note.
Notably, certain plant species preferred at Gombe—such as Grewia spp.—are also used by chimpanzee groups thousands of kilometers away, raising questions about whether mechanical properties influence widespread cultural traditions.
Implications for Human Evolution
Chimpanzees are our closest living relatives, and their tool use provides valuable insights into early human technology. While stone tools survive in the archaeological record, perishable materials like wood and plant fibers do not, leaving gaps in our understanding of early tool behavior.
By studying chimpanzee material selection, researchers can infer the types of tools early hominins might have crafted and the thought processes that went into them.
“This finding has important implications for understanding how humans might have evolved their remarkable tool-using abilities,” says Adam van Casteren, a co-author of the study.
Future research could explore how young chimpanzees learn these skills, whether through observation, imitation, or trial and error. Understanding this learning process could shed light on the cognitive abilities that set early humans apart.
Related Research
Stout, D., Semaw, S., Rogers, M. J., & Cauche, D. (2010). Technological variation in the earliest Oldowan from Gona, Afar, Ethiopia. Journal of Human Evolution, 58(6), 474-491. https://doi.org/10.1016/j.jhevol.2010.02.005
Braun, D. R., & Harris, J. W. K. (2003). Technological developments in the Oldowan of Koobi Fora: Innovative techniques for reconstructing technological capabilities of early hominins. Journal of Human Evolution, 44(3), 379-401. https://doi.org/10.1016/S0047-2484(02)00205-8
Luncz, L. V., Mundry, R., & Boesch, C. (2012). Evidence for cultural differences between neighboring chimpanzee communities. Current Biology, 22(10), 922-926. https://doi.org/10.1016/j.cub.2012.03.031
Pascual-Garrido, A., Carvalho, S., Mjungu, D., Schulz-Kornas, E., & van Casteren, A. (2025). Engineering skills in the manufacture of tools by wild chimpanzees. iScience, 112158, 112158. https://doi.org/10.1016/j.isci.2025.112158
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