Two anthropologists watched in mixed amazement and horror as several female chimpanzees crafted spears and used them to somewhat brutally hunt smaller mammals.

Following a troop of the primates in a Senegalese savanna, Jill Pruetz of Iowa State University and Paco Bertolani of Cambridge observed them breaking the branches off of trees, picking leaves from the sides, and sharpening the tips to deadly points. In the March edition of Current Biology, the scientists explained that such sophisticated animal behavior could reveal a great deal about how early humans used primitive tools.

Via CNN