A five-year study by Wageningen University and the German Primate Research Center found that wild chimpanzees in Guinea-Bissau repeatedly strike stones against trees, [1]presumably as a form of communication . Phys.Org reports:

> Over the course of a five-year field study, the research team collected [2]video footage at five distinct locations within a nature reserve in Guinea-Bissau. This was made possible through the use of camera traps and with essential support from local field guides. In specific areas, a striking behavioral pattern was observed: adult male chimpanzees repeatedly struck stones against tree trunks, resulting in characteristic piles of stones at the base of these trees. [...]

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> The observations point to cultural transmission. Young chimpanzees adopt the behavior from older group members, indicating that it is learned socially rather than genetically inherited. Marc Naguib, Professor of Behavioral Ecology, underscores the broader significance of the discovery: "It illustrates that culture is not unique to humans and that such behaviors need to be considered also in nature conservation."

The study is [3]published in the journal Biology Letters .



[1] https://phys.org/news/2025-05-year-chimpanzees-stones-trees-communication.html

[2] https://www.youtube.com/watch?v=JCVarNrrTFg

[3] https://royalsocietypublishing.org/doi/10.1098/rsbl.2025.0053