Coevolution between Grasping Ability and Forelimb Shape in Strepsirrhines and Platyrrhines
Résumé
Fine prehensile activities are thought to be uniquely associated with the evolution of human
hands and with tool-making and tool-use in the earliest humans. However, there is no holistic
approach establishing the link between the morphology of the forelimb and grasping ability in
living primates. The present study aims to understand the relationships between grasping behaviour and the morphology of forelimb in a phylogenetic framework in strepsirrhines and platyrrhines. On one hand, we analyzed behavioural data on food prehension (grasping with the mouth, one hand, two hands, the mouth and one hand, the mouth and two hands) for 92 individuals belonging to 22 species of strepsirrhines and 30 individuals belonging to 11 species of platyrrhines. On the other hand, we performed geometric morphometric approaches on the long bones of the forelimb obtained from collection specimens. Thus, we evaluate the strength of the covariation between grasping behaviour and forelimb bone shape in primates. The data obtained show a phylogenetic signal in forelimb morphology in primates in relation to grasping and manipulation behaviour. Our results indicate that there is a co-evolution between grasping behaviour and the shape of the humerus and radius. Interestingly, strong differences in grasping behaviour and forelimb shape are observed between nocturnal and diurnal species of strepsirrhines.