Orangutans (Pongo spp.) have been observed to spontaneously use tools of various kinds to achieve their objectives. But researchers from The Great Ape Trust, Des Moines, IA, and Iowa State University wondered whether, given the choice, they might prefer to go for a functional tool (stiff) or a non-functional (floppy) tool. Their experimental study presented three orangutans (Allie, Azy and Knobi) with a previously unseen choice of tools to get at a food reward placed just out of their reach. The three sets of tools, a wooden stick, a piece of hose and a PVC tube (all 75 cm long) were presented in pairs, one of which was stiff and rather useful, and the other floppy and relatively useless. [see photo]
Results:
“The functional tool was selected in nearly all trials. Moreover, two of the orangutans demonstrated this within the first test trials with each of the three tool types.”
See: Orangutans (Pongo spp.) May Prefer Tools With Rigid Properties to Flimsy Tools, Journal of Comparative Psychology, 2010, Vol. 124, No. 4, 351–355.