Chimpanzees have been hurling rocks at the same trees for more than a decade

Some chimpanzees in West Africa repeatedly throw rocks at particular trees, creating piles of stones that can remain in use for more than a decade. Researchers think this unusual behavior may be cultural and could serve as a form of communication, territorial signaling, or something more symbolic.

Camera traps and audio recordings are now being used to reveal who throws the stones and how nearby chimpanzees respond.