Chimpanzees have been known to use stones as tools, but researchers from the Max Planck Institute for Evolutionary Anthropology recently observed some employing rocks in a decidedly different way.

Chimpanzees have been known to use stones as tools, but researchers from the Max Planck Institute for Evolutionary Anthropology recently observed some employing rocks in a decidedly different way.
Video captured via camera traps installed in a variety of West African locations shows a number of male chimps simultaneously howling and throwing stones at trees.
The researchers also observed that some of the tree interiors had