For the first time, great apes have been observed making and using tools to hunt mammals, according to a new study. The discovery offers insight into the evolution of hunting behavior in early humans.

No fewer than 22 times, researchers documented wild chimpanzees on an African savanna fashioning sticks into "spears" to hunt small primates called lesser bush babies.

In each case a chimpanzee modified a branch by breaking off one or two ends and, frequently, using its teeth to sharpen the stick. The ape then jabbed the spear into hollows in tree trunks where bush babies sleep.

When hunting in the hollows, "almost without fail, every time they would withdraw the tool, they would sniff it or lick it, and