Transport of Functionally Appropriate Tools by Capuchin Monkeys (Cebus apella)

Abstract

Capuchin monkeys (Cebus sp.) are notable among New World monkeys for their widespread use of tools. Like chimpanzees, they use both hammer tools and insertion tools in the wild to acquire food that would be unobtainable otherwise. Recent evidence indicates that capuchins transport stones to anvil sites and use the most functionally efficient stones to crack nuts. We further investigated capuchins' assessment of functionality by testing their ability to select a tool that was appropriate for two different tool-use tasks: A stone for a hammer task and a stick for an insertion task. To select the appropriate tools, the monkeys investigated a baited tool-use apparatus (insertion or hammer), traveled to a location in their enclosure where they could no longer see the apparatus, made a selection between two tools (stick or stone), and then could transport the tool back to the apparatus to obtain a walnut. We incorporated tool transport and the lack of a visual cue into the design to assess willingness to transport the tools and the monkeys' memory for the proper tool. Six brown capuchins (Cebus apella) were first trained to select and use the appropriate tool for each apparatus. Four animals completed training and were then tested by allowing them to view a baited apparatus and then travel to a location 8 m distant where they could select a tool while out of view of the apparatus. All four monkeys chose the correct tool significantly more than expected and transported the tools back to the apparatus. Results confirm capuchins' propensity for transporting tools, demonstrate their capacity to select the functionally appropriate tool for two different tool-use tasks, and indicate that they can retain the memory of the correct choice during a travel time of several seconds.

Impact of stimulus format and reward value on quantity discrimination in capuchin and squirrel monkeys

“…Subjects and housing Subjects were seven brown capuchin monkeys (Cebus [Sapajus] apella; five females; mean age 8.43 + 3.51 years) and six squirrel monkeys (Saimiri sciureus; six females; mean age 10.17 + 3.49 years) housed in social colonies at Bucknell University. All subjects had extensive experience with manual cognitive testing (e.g., Judge & Bruno, 2012;Judge, Evans, Schroepfer, & Gross, 2011;Kurdziel & Judge, 2007;Marsh, Vining, Levendoski, & Judge, 2015;Zander & Judge, 2015) but not with quantity discrimination specifically. All subjects were tested alone in their home cage by temporarily closing off small sections of the housing area.…”

Understanding Solidity: Investigating Knowledge of a Functional Object Property in Brown Capuchin Monkeys (Sapajus apella) and Common Squirrel Monkeys (Saimiri sciureus)

“…This requires an additional cognitive ability, as the individual must plan their action ahead of time. However, in previous tasks, capuchins have been able to select the correct tool in advance of being given access to an apparatus (Manrique et al, 2011) and have even been shown to travel 8 m to a different room to collect the appropriate tool after viewing an apparatus (Evans & Westergaard, 2004;Judge & Bruno, 2012). The planning involved in the two-trap task is no more demanding than in these previous tasks, and thus, is unlikely to be the only factor limiting their ability.…”

“…Although, as a group, the capuchin monkeys performed above chance, all 14 individuals failed to avoid the traps. The result was surprising, as there is strong evidence that capuchin monkeys can learn functional discriminations (Evans & Westergaard, 2004;Fujita et al, 2003Fujita et al, , 2011Judge & Bruno, 2012;Manrique et al, 2011;Painter et al, 2019;Sabbatini et al, 2014;Schrauf et al, 2008;Yocom & Boysen, 2010), with some evidence of this in squirrel monkeys (Painter et al, 2019). One explanation for their failure is the planning involved in the task.…”

“…This is especially true for new world monkeys where their performance in tests designed to investigate object knowledge has been notably inconsistent. Within the literature, there is evidence that both non-tool-using and tool-using new world primates are able to learn to identify and select the most appropriate or efficient tools for retrieving food, based on perceptual tool properties (capuchin monkeys: Evans & Westergaard, 2004;Fujita et al, 2003Fujita et al, , 2011Judge & Bruno, 2012;Manrique et al, 2011;Mayer et al, 2014;Painter et al, 2019;Sabbatini et al, 2014;Schrauf et al, 2008;Visalberghi & Neel, 2003;Yocom & Boysen, 2010;common marmosets: Gagne et al, 2012;Yamakazi et al, 2011;cottontop tamarins: Hauser et al, 1999cottontop tamarins: Hauser et al, , 2002Santos et al, 2005Santos et al, , 2006; squirrel monkeys: Painter et al, 2019). However, although findings showing the preferential selection of functional tools provide support for the idea that new world monkeys are sensitive to the efficiency of tools, such studies do not confirm that the monkeys do so by forming abstract representations of the object properties involved in the tools' functionality.…”

Three Levels of Consciousness: A Pattern in Phylogeny and Human Ontogeny

“…In studies with bonobos, orangutans, and chimpanzees, Mulcahy and Call (2006) and Osvath and Osvath (2008) observed that apes saved tools for future use. Contrary to this, macaques and capuchin monkeys did not spontaneously transport tools for future use but could be trained to do so (Bourjade, Thierry, Call, & Dufour, 2012;Dekleva, van den Berg, Spruijt, & Sterck, 2012;Judge & Bruno, 2012).…”