Patterns, Variability, and Flexibility of Hand Posture During Locomotion in Primates

Primates are defined, in part, by the presence of a grasping hand that couples primitive anatomy with exceptional neuromuscular dexterity. This arrangement is maintained across the evolutionary history of primates, and is often seen as one of the key features that allow primates to make fluid transitions from one substrate to another, make kinematic adjustments with changes in speed and gait, and to make biomechanical adjustments throughout ontogeny. This chapter surveys the exceptional diversity of primate hand positions across locomotor modes, and provides a perspective on the organization of hand positioning based on underlying biomechanical similarities. Across primates, hand positions are highly variable, and multiple solutions to same locomotor challenges are observed. This mechanical flexibility appears to be an adaptive feature of the primate hand, and suggests much of the success of the primate radiation has to do with maintaining generalized ‘cheiridial compromise’ that allows locomotor versatility.