Food properties influence grasping strategies in strepsirrhines

Though hand-grasping is ubiquitous in primate species, its origins remain uncertain. This is in part because uncertainty about hand skills and grasping strategies persists in strepsirrhines, a monophyletic group of primates located near the base of the primate tree. In this study, we report and discuss our observations of the different grasping strategies adopted by 85 captive individuals belonging to 22 species of strepsirrhines during grasping of food items having different size and consistency. Our results indicate that even though strepsirrhines do not present variability in their hand-grip types (sole whole-hand power-grip), they are able to adjust their grasping strategy depending on the food properties. Notably, they use the mouth when more precision is needed (i.e. to grasp small items). Moreover, grasping strategies adopted for big items differ depending on food consistency, revealing a new potential essential factor to consider in future research on grasping abilities. We believe that by looking across this important set of species in unconstrained standardized conditions, this study provides valuable insight for further comparative research discussing the potential selective pressures involved in the evolution of hand-grasping.