Object grasping and manipulation in capuchin monkeys (genera Cebus and Sapajus)

Abstract

The abilities to perform skilled hand movements and to manipulate objects dexterously are landmarks in the evolution of primates. The study of how primates use their hands to grasp and manipulate objects in accordance with their needs sheds light on how these species are physically and mentally equipped to deal with the problems they encounter in their daily life. We report data on capuchin monkeys, highly manipulative platyrrhine species that usually spend a great deal of time in active manipulation to search for food and to prepare it for ingestion. Our aim is to provide an overview of current knowledge on the ability of capuchins to grasp and manipulate objects, with a special focus on how these species express their cognitive potential through manual behaviour. Data on the ability of capuchins to move their hands and on the neural correlates sustaining their actions are reported, as are findings on the manipulative ability of capuchins to anticipate future actions and to relate objects to other objects and substrates. The manual behaviour of capuchins is considered in different domains, such as motor planning, extractive foraging and tool use, in both captive and natural settings. Anatomofunctional and behavioural similarities to and differences from other haplorrhine species regarding manual dexterity are also discussed. ADDITIONAL KEYWORDS: bimanual coordination-exploration-extractive foraging-manual dexteritymotor planning-power grip-precision grip-thumb opposability-tool use.

Optional tool use: The case of wild bearded capuchins (Sapajus libidinosus) cracking cashew nuts by biting or by using percussors

“…Consistent with most other studies (e.g., Eadie, 2015;Gunst et al, 2008;Gunst, Leca, et al, 2010;Truppa, Carducci, et al, used to compare these two conditions. All tests were two-tailed.…”

“…As the exact age of the oldest individuals was unknown, nonparametric Spearman rank‐order correlation coefficients were used to assess whether some variables differed in relation to age. Consistent with most other studies (e.g., Eadie, 2015; Gunst et al, 2008; Gunst, Boinski, et al, 2010; Gunst, Leca, et al, 2010; Truppa, Carducci, et al, 2019), we used age (instead of body mass) as a proxy for body strength. Note that the age and the body mass strongly covaried in our data set ( r s = 0.68; N = 12; p < .05; using body mass data collected for 12 out of 14 individuals by the Etho Cebus team in May–June 2015).…”

“…There is a vast literature indicating that capuchins are extremely skilled, compared with other nonhuman primate species, in grasping and manipulating objects (for a review see, Truppa, Carducci, et al, 2019). Young primates require lengthy practice to become as efficient as adults at acquiring foods requiring extensive perceptual learning for detection (e.g., larvae embedded in bamboo or palm fruits), fine motor coordination and/or substantial postcranial strength (Eadie, 2015; Gunst et al, 2008; Gunst, Boinski, et al, 2010; Gunst, Leca, et al, 2010; Ottoni et al, 2005; Rapaport & Brown, 2008; Schuppli et al, 2016; Truppa, Marino, et al, 2019).…”

Anticipating future actions: Motor planning improves with age in wild bearded capuchin monkeys (Sapajus libidinosus)

“…Capuchins' ancestral lineage diverged 30–40 million years ago from that of the other haplorrhine primates, humans included (Schrago & Russo, 2003). Capuchins improve their locomotor skills rapidly once they begin to spend time off the mother around three months of age (Fragaszy et al, 2004), yet their proficiency in exploiting hard‐to‐process foods, which require strength and/or fine hand movements, develops over years (e.g., Eadie, 2015; Fragaszy & Adams‐Curtis, 1997; Gunst et al, 2010; Truppa et al, 2019; Truppa et al, 2019; Visalberghi et al, 2016). We expected that infant capuchins, which were independent enough from their mother to participate in our study, would show motor anticipation, as 19‐month‐old human infants do (McCarty et al, 1999).…”

Manual skills for processing plant underground storage organs by wild bearded capuchins

“…Capuchin monkeys routinely exploit fruits with hard teguments, xylophagous insects and underground plant parts (Eadie, ; Fragaszy, Visalberghi, & Fedigan, ; O'Malley & Fedigan, ; Perry & Manson, ; Terborgh, ). Capuchins' proficiency in extractive foraging is related to their persistent interest in manipulating objects, and to their manual dexterity, evident in the large variety of movements they perform (Fragaszy et al, ; Truppa, Carducci, & Sabbatini, ). Among platyrrhines, capuchins show outstanding extractive foraging techniques which resemble those used by catarrhine species, such as baboons ( Papio spp.…”