![chimpanzee hand morphology chimpanzee hand morphology](http://www.columbia.edu/itc/eeeb/shapiro/w3030/images/chimp_foot_Zambia.%201.jpeg)
Hence, this study quantifies the shape of the MC1's body in the extant Homininae and some fossil hominins to provide a better characterization of its morphology. This could provide further insights into its anatomy, as well as its relationship with manipulative capabilities.
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Despite its possible importance regarding this issue, the body of the first metacarcapal (MC1) has not been fully characterized using morphometrics. The morphological characteristics of the thumb are of particular interest due to its fundamental role in enhanced manipulation. 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. 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. 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. 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. In contrast, the study of bonobos' manipulative abilities has almost exclusively been carried out in experimental contexts related to tool use. 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. ramidus.Ĭomparative behavioral studies of hand use amongst primate species, including humans, have been central in research on evolutionary mechanisms. Panels (c) and (d) depict the EHP of chimpanzees and humans vis-à-vis their reconstructed last common ancestor (LCA) assuming, respectively, 50.8 kg and 35.7 kg for Ar. ramidus are plotted in this phylomorphospace to help visualizing major shape changes occurred during ape and human hand evolution. Outlines (scaled to similar length) of extant and fossil apes and Ar.
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Owing to space constrictions, macaque species are not labelled. (a) EHP of Ardipithecus ramidus estimated using 50.8 kg. Taxa are colour-coded as in the phylogenetic tree internal nodes (that is, ancestral-states reconstructed using maximum likelihood) are also indicated, highlighting the positions in shape space of the great ape-human and chimpanzee-human LCAs (plus 95% confidence intervals for the latter estimate). Phylomorphospace projection of the phylogeny presented in onto the two first principal components (PCs) of extrinsic hand proportions (EHP) in extant and fossil species. The evolutionary history of human and ape hand proportions.