Savannah-dwelling chimpanzees such as these can make spear-like weapons to hunt other primates. Researchers saw 10 different chimps fashioning spear-like tools to forcibly jab at nocturnal monkeys that hide inside hollow branches or tree trunks during the day. After their attacks, the chimps sniffed or licked their weapons, as if to see whether or not they shed blood. Credit: Paco Bertolani