Chimpanzees living in the West African savannah have been observed fashioning deadly spears from sticks and using the hand-crafted tools to hunt small mammals -- the first routine production of deadly weapons ever observed in animals other than humans.
Using their hands and teeth, the chimpanzees were repeatedly seen tearing the side branches off long straight sticks, peeling back the bark and sharpening one end, the researchers report in today's on-line issue of the journal Current Biology. Then, grasping the weapon in a "power grip," they jabbed into tree-branch hollows where bush babies -- small monkey-like mammals -- sleep during the day.
Scientists have documented tool use among chimpanzees for several decades, but the tools have been simple and used to extract food rather than to kill it.
Some chimpanzees slide thin sticks or leaf blades into termite mounds, for example, to fish for the tasty, crawling morsels. Others crumple leaves and use them like sponges to sop drinking water from tree hollows.
Unlike other chimpanzee sites currently under study, which are forested, this site is mostly open savannah. That environment is very much like the one in which early humans evolved and is different enough from other sites to expect differences in chimpanzee behaviors.
Eventually the research duo documented 22 instances of spear-making and use, two-thirds of them involving females.
After every few jabs, the chimpanzee would sniff or lick the tip, as though testing to see if it had "caught" anything.