Manipulative repertoire of bonobos (Pan paniscus) in spontaneous feeding situation

Abstract

Comparative behavioral studies of hand use amongst primate species, including humans, have been central in research on evolutionary mechanisms. In particular, the manipulative abilities of our closest relatives, the chimpanzee (Pan troglodytes), have been widely described in various contexts, showing a high level of dexterity both in zoo and in natural conditions. In contrast, the study of bonobos' manipulative abilities has almost exclusively been carried out in experimental contexts related to tool use. The objective of the present study is to describe the richness of the manipulative repertoire of zoo‐housed bonobos, in a spontaneous feeding context including various physical substrates to gain a larger insight into our evolutionary past. Our study describes a great variety of grasping postures and grip associations in bonobos, close to the range of manipulative repertoire in chimpanzees, confirming that the two species are not markedly different in terms of cognitive and morphological constraints associated with food manipulation. We also observed differences in manipulative behaviors between juveniles and adults, indicating a greater diversity in grip associations and grasping postures used in isolation with age, and a sex‐biased use of tools with females using tools more often than males. These results are consistent with the previous results in the Pan genus and reinforce the hypothesis that the evolutionary mechanisms underlying the flexibility of manipulative behaviors are shared by both species and that these ecological strategies would have already evolved in their common ancestor.

Form, function and evolution of the human hand

“…Like chimpanzees, zoo‐housed bonobos most commonly use a two‐jaw chuck pad‐to‐side grip (Figure 4e) and V‐pocket grips, but they are also capable of one‐handed in‐hand movements (Bardo et al, 2016). During feeding, the power and precision grip manipulative repertoire of zoo‐housed bonobos is similar to that seen in chimpanzees, with the pad‐to‐side of digit 2 and a power grip with the pollex being two of the most common grips used (Gérard et al, 2022). Sanctuary bonobos are as efficient at nut‐cracking with stone hammers as wild Bossou chimpanzees, and when the former cracked nuts they used a variety of precision and power grips to manipulate the hammers, some of which have not been described previously in other apes (Neufuss, Humle, et al, 2017; Figure 5a,b).…”

“…Like chimpanzees, zoo-housed bonobos most commonly use a two-jaw chuck pad-to-side grip (Figure 4e) and V-pocket grips, but they are also capable of one-handed in-hand movements (Bardo et al, 2016). During feeding, the power and precision grip manipulative repertoire of zoo-housed bonobos is similar to that seen in chimpanzees, with the pad-to-side of digit 2 and a power grip with the pollex being two of the most common grips used (Gérard et al, 2022).…”

Reach-to-grasp kinematic signatures in Colombian spider monkeys (Ateles fusciceps rufiventris).

“…In the current study, the smaller item (cereal) was hard whereas the larger item (grape) was soft. By rigorously exploring object properties, not only would we be able to tease apart reach-to-grasp comparisons across species, but we would also be able to create a comprehensive grasp catalog for spider monkeys, like prior work in other nonhuman primate species (e.g., Byrne et al, 2001; Christel, 1993; Gérard et al, 2022; Jones-Engel & Bard, 1996; Macfarlane & Graziano, 2009; Marzke & Wullstein, 1996; Pouydebat et al, 2009, 2011; Spinozzi et al, 2004; Truppa et al, 2016). Taken together, we see further characterizing the different grasps used by spider monkeys as a key research target for advancing our understanding of how the lack of a thumb impacts reach-to-grasp actions.…”

Reach-to-grasp kinematic signatures in Colombian spider monkeys (Ateles fusciceps rufiventris)

“…In the current study, the smaller item (cereal) was hard whereas the larger item (grape) was soft. By rigorously exploring object properties, not only would we be able to tease apart reach-to-grasp comparisons across species, but we would also be able to create a comprehensive grasp catalog for spider monkeys, like prior work in other nonhuman primate species (e.g., Byrne et al, 2001;Christel, 1993;Gerard et al, 2022;Jones-Engel & Bard, 1996;Macfarlane & Graziano, 2009;Marzke & Wullstein, 1996;Pouydebat et al, 2009;Pouydebat et al, 2011;Spinozzi et al, 2004;Truppa et al, 2016). Taken together, we see further characterizing the different grasps used by spider monkeys as a key research target for advancing our understanding of how the lack of a thumb impacts reach-to-grasp actions.…”