Oral Tool Use by Captive Orangutans (Pongo pygmaeus)

Abstract

Eight captive orangutans (Pongo pygmaeus) were given wooden blocks embedded with raisins and bamboo as raw material for tool making in a study of manual laterality. In about three quarters of the raisin extraction bouts, the orangutans held the tool in the lips or teeth rather than in their hands. Three adult males and 2 adult females showed extreme (≥92%) preference for oral tool use, a subadult male and an adult female used oral tools about half the time, and 1 adult female preferred manual tool use. Most oral tool users made short tools (approx. 4–10 cm long) that were held in the lips and (probably) supported by the tongue. Preference for oral tool use does not correlate with body weight, age or sex, but it may be related to hand size or individual preference. This is the first report of customary oral tool use as the norm in captive orangutans; it resembles the behavioral patterns reported by van Schaik et al. and Fox et al. in nature.

Estimating thumb–index finger precision grip and manipulation potential in extant and fossil primates

“…Furthermore, the other primates known to be particularly dexterous-Pan, Papio and Macaca-have the same mean and peak manipulation WS as the general 'primate' pattern (despite large variation in thumb-index proportions and joint mobility), which does not support our hypothesis that these taxa would have higher thumb-index finger manipulation than other primates. Pongo, as predicted, demonstrates a much lower mean and peak thumb-index finger WS compared with all other primates (except Presbytis) for small-and medium-sized objects (R , 0.18), which may help to explain why they often use within-finger grips or the mouth to manipulate objects [24,49] (electronic supplementary material, figure S2). …”

Tool Use to Modify Calls by Wild Orang-Utans

“…To date, only a few observations of tool using and manufacturing by wild orangutans have been reported [1,2], even though rehabilitated and captive orang-utans use and manufacture tools frequently [3][4][5]. Here it is reported that wild orang-utans use leaves as a tool to modify their kiss-squeak calls made during agonistic displays.…”

Cortical Orofacial Motor Representation in Old World Monkeys, Great Apes, and Humans

“…Interspecific differences in noncommunication orofacial skills might also explain some of the variation in cytoarchitecture. Orang-utans in the wild and captivity, for example, have been noted to exhibit particular facility at manipulating tools with their lips, teeth, and tongue during extractive foraging of insects and seeds [van Schaik et al, 1996;O'Malley and McGrew, 2000].…”