The evolution of hominoid ecomorphology studies of locomotor behaviour and anatomy in human and nonhuman apes

An animal’s locomotor abilities facilitate its interactions with the surrounding environment. Extant hominoids (apes) have evolved diverse ranges of locomotor strategies which allow them to exploit terrestrial and arboreal habitats despite their large body size. However, hominins (modern humans and their ancestors) are traditionally defined by their restriction to upright, bipedal posture and locomotion. Reconstructions of locomotor capacity in fossil hominoids allow investigation of the evolution of extant ape locomotion; yet these reconstructions rely on detailed understanding of the relationships between morphology, locomotor behaviour and the environment in extant apes. This thesis explores variation in locomotor behaviour and skeletal morphology among extant apes in order to shed light on these relationships. Studies of chimpanzees, gorillas and modern humans reveal considerable mechanical variation in gait, and demonstrate the importance of considering environmental context in ape locomotion. Anatomical studies find reduced reliability of inferring locomotor capacity in fossil hominoids due to significant variation among extant apes in skeletal predictors of habitual bipedality and estimations of joint range of motion. These studies highlight the importance of behavioural flexibility in determining hominoid locomotor capacity, and suggest that fossil hominoids were less constrained in their locomotor repertoires than previous reconstructions imply