Knuckle-walking and the evolution of hominoid hands

摘要: Knuckle-walking is a pattern of digitigrade locomotion unique to African apes among Primates. Only chimpanzees and gorillas are specially adapted for supporting weight on the dorsal aspects middle phalanges flexed hand digits II–V. When forced ground, most orangutans assume one variety postures, but they cannot knuckle-walk. Some place their hands in palmigrade postures which impossible apes. The knuckle-walking plantigrade feet both morphologically adaptively distinct from those Pongo, nearest relative extant These features associated with common adaptive shift terrestrial support placing same genus Pan. It further suggested than Pan comprises subgenera (a) Pan, including P. troglodytes pygmy chimpanzees, (b) Gorilla, mountain lowland populations gorilla. African probably diverged ancestral pongids that were distributing terminal branches forest canopy. Early adjustments may have involved fist-walking later evolved into knuckle-walking. Orangutans continued adapt feeding canopy became highly specialized four-digit prehension. Although retained arboreal nesting habits, moved tree by routes less restricted habitat. While adapting diet ground plants increased size point frequent them orangutans. Early hominids had not developed prospective adaptations knuckle-walking, therefore did evolve through stage. Initial quadrupedal resting stance included posturing. Their thumbs been already well as an adaptation grasping during climbing. A combination selection pressures efficient locomotor object manipulation advanced early hominid toward modern human configuration.