Functional and behavioral variation in intrinsic hand and foot digit proportions in primates

作者：Séverine Toussaint, Vincent D'Amato, Joanna Desmidt, Mélanie Berthet, Benoît Quintard, François Druelle · 发表于：Journal of Human Evolution · 年份：2025 · DOI：10.1016/j.jhevol.2025.103679 · 被引用次数：1 · 研究领域：Primate Behavior and Ecology、Hemispheric Asymmetry in Neuroscience、Evolutionary Psychology and Human Behavior

The relative elongation of the digits on the autopods has long been considered as an adaptation for an arboreal lifestyle shared by several tetrapods. In primates, this morphological adaptation constitutes one of the defining characters of the order and is correlated to their enhanced manual and pedal grasping capabilities. However, primates are highly diversified in terms of body mass and locomotor repertoire, and it remains unclear to what extent the elongation of proximal and intermediate phalanges relative to metapodials (i.e., the phalangeal index) correlates with body mass or grasping performances during arboreal locomotion. In this study, we tested the effect of body mass, grasping performance, and phylogeny on the manual and pedal phalangeal indexes in 58 species of nonhuman primates, including strepsirrhines, platyrrhines, and catarrhines. We computed a grasping score as a proxy for grasping performance based on the known locomotor repertoire of each species. We found that body mass negatively correlates with the intrinsic digit proportions of the hand, whereas the grasping score positively correlates with the intrinsic digit proportions of both the hand and foot. Our results highlight the different functional roles of the hand and foot in nonhuman primates. The hand is more influenced by changes in body size (allometric constraints), while the foot primarily functions to anchor to arboreal supports. Moreover, finger elongation appears most critical for enhancing gra...