Chimpanzees hunt with spears

This news isn't new, but it still amazes me: chimpanzees hunt with spears. Specifically, Jill Pruetz and Paco Bertolani have observed a newly habituated troop of Western chimpanzees in Fongoli, Senegal habitually using wooden spears to hunt lesser bush babies. (Pruetz and Bertolani reported this discovery back in early 2007 in their paper, "Savanna Chimpanzees, Pan troglodytes verus, Hunt with Tools"). While it is well known that chimps hunt red colobus monkeys, bush babies are rarely preyed upon, possibly because they are small and nimble. Unlike colobus monkeys, bush babies are nocturnal and spend the day sleeping in tree hollows - and that's where the Fongoli chimps hunt them.

First, the chimps fashioned their spears: generally speaking, they broke off a living branch, trimmed the side branches off, and sometimes they stripped the entire branch of bark and occasionally even sharpened one end by biting it multiple times. (See an example of a spear, left). Then the chimps "forcefully jabbed" the spear multiple times into suspected bush baby cavities and then smelt and/or licked it on extraction. At the time of the article's publication, in only incident was a chimpanzee observed actually extracting a bush baby after spearing a cavity, but several other individuals were seen eating bush baby meat. (And Pruetz's observations are ongoing). This remarkable behavior can be seen in the clip embedded below (the real action starts at around 4:00):



Interestingly, while colobus hunts are cooperative and male dominated, bush baby spearing is solitary and generally carried out by females and immature individuals. Pruetz and Bertolani speculate "that individuals whose access to preferred resources such as meat is limited by social or physical factors respond by developing alternative means with which to acquire them" (2007: 414). In other words, lack of access through usual means forces some chimpanzees to get creative and invent new ways to acquire desirable resources. This has obvious implications for human evolution: Miocene apes are thought to have evolved in a climate not dissimilar to that of Savannah chimpanzees and this paper's findings may thus "support the hypothesis that female hominids play a role in the evolution of the earliest tool technology, and we suggest that these technologies included hunting-related behavior, in addition to gathering-related activities" (2007: 414).

Amazingly, the Fongoli chimpanzees exhibit two further never-before-seen behaviors: using caves during the day to stay cool and bathing in water (see the video). These three cultural innovations together suggest there may be something to the theory that hominid evolution was driven by drought during the Miocene which caused woodlands to contract and the Savannah to expand. In conclusion: primatology rocks!

(See also: National Geographic's article on the chimps of Fongoli).

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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