Last year Jill Pruetz and Paco Bertonali published data from observations from March 2005 to July 2006 that chimpanzees in a community in Senegal fashioned wooden tools to use for hunting.

Their target? The lesser bushbaby (Galago senegalensis):



Bushbabies are nocturnal prosimians that curl up and sleep in the hollows of trees during the day. When roused from sleep, they're extremely quick, and scurry or jump from tree to tree to elude predators.

The chimpanzees are thought to use the wooden tools to jab into tree hollows to stun or wound the bushbaby prey. The chimps were seen inspecting the tools after jabbing them into hollows, either sniffing or licking them. In the one successful case of hunting observed, the chimp jumped up and down on the tree after jabbing the tool into the hollow, and extracted a bushbaby that did not vocalize and appeared to be incapacitated. That chimp, an adolescent female, then tore the bushbaby apart and ate it.

Here's a screenshot of a chimp holding such a tool in her mouth:



Some researchers have criticized the use of the word "spear" as perhaps a bit loaded. These tools averaged 63 cm (about 2 feet), and they weren't hurled at prey. But they were seen to be constructed on 26 different occasions, and the tools were modified in multi-step processes that involved trimming off leaves and side branches, stripping bark, and trimming the tip (though not all steps were followed for all tools, and in some cases steps were skipped).

One of the more interesting findings in this study is that the chimps making tools spanned a wide range of ages and included both males and females, which is suggestive that the origin of tool use in hunting in our own lineage may not have been the product of males. The stereotype of the caveman hunter and the cavewoman gatherer might need to be amended.

I'm not so hung up on the particulars of what to call such tools or such activities. What is clear is that the more we study our close relatives, the more they seem to surprise us with behaviors we assumed they were not capable of.

PRUETZ, J., BERTOLANI, P. (2007). Savanna Chimpanzees, Pan troglodytes verus, Hunt with Tools. Current Biology, 17(5), 412-417. DOI: 10.1016/j.cub.2006.12.042