Chimpanzee mating tools

John Tierney riffs on a short review paper by William McGrew, a brief tour of chimpanzee technology. In a pool of academese, he finds a salacious bubble:

He tactfully waits until the third paragraph journalists call this burying the lead to deliver the most devastating blow yet to human self-esteem. After noting that chimpanzees tool kits are now known to include 20 items, Dr. McGrew casually mentions that theyre used for various functions in daily life, including subsistence, sociality, sex, and self-maintenance.
Sex? Chimpanzees have tools for sex? No way. If ever there was an intrinsically human behavior, it had to be the manufacture of sex toys.

Needless to say, the reality isn’t as provocative as it sounds. Unless you’re a chimp.

The review paper itself is rather short and the basic theoretical ideas are not new, but McGrew includes several examples from relatively new field sites. I like the “cleaving” example described here:

Among all animals, only chimpanzees appear to be able to use one type of raw material to make many kinds of tools (e.g., leaf as sponge, napkin, or fishing probe), or make one kind of tool from many raw materials (fishing probe from grass, bark, vine, and twig). Only chimpanzees have been shown to vary in their tool use at a multitude of levels, from individual, family, community, and population to subspecies. Chimpanzees also continue to yield new forms of tool use from continuing study (17, 18): In the Nimba Mountains of Guinea, they "cleave" fibrous, basketball-sized fruits into manageable smaller pieces, using hammers and anvils (19); this is unlike nut-cracking, for example, which cracks open natural containers to get at the goal item inside.

You have to be careful of that “among all animals” – like the white crow, it’s just begging for somebody to find one example to disprove the generalization.

McGrew mentions efforts to find characteristic signs of usewear that would distinguish ancient chimpanzee artifacts from Oldowan-type implements made by hominins. I think this will be more of a problem when we start finding significant Plio-Pleistocene (or earlier) archaeology outside of East and South Africa. In those places so far we have no signs of fossil chimpanzees from prior to the Middle Pleistocene, and rarely then. There’s some interesting new work on chimpanzee population structure that may bear on the question of where they used to live – I’ll share that when I get a chance.

References:

McGrew WC. 2010. Chimpanzee technology. Science 328:579-580. doi:10.1126/science.1187921