5/29/2023 0 Comments Weathering effects with meshlab![]() Additionally, the phalanges are long and curved, enabling them to resist the bending strains incurred during pedal grasping 13. The extant great ape forefoot is characterized by an abducent opposable hallux and metatarsal (MT) heads that are plantarly oriented in sagittal profile and dorsally narrow 1, 9, 10, 11, 12. Among the features affected by these changes, those of the forefoot region have received much attention in comparative morphology studies due to their role in the push-off phase of bipedal walking 1, 2, 3, 4, 5, 6, 7, 8. Analyses of Australopithecus afarensis metatarsals reveal morphology intermediate between humans and chimpanzees, suggesting that this species used different bipedal push-off kinematics than modern humans, perhaps resulting in a less efficient form of bipedalism.ĭuring the evolution of bipedalism the hominin foot underwent a number of dramatic changes that converted it from a prehensile grasping organ to a strong propulsive lever. This kinematic pattern is mirrored in the morphometric analyses of metatarsal head shape. Among MTPJs 2–5, both species exhibit decreasing peak angles from medial to lateral. Using three-dimensional kinematic and morphometric analyses, we show that humans push off with greater peak dorsiflexion angles at all MTPJs than do chimpanzees during bipedal and quadrupedal walking, with the greatest disparity occurring at MTPJ 1. The morphological affinity of the metatarsal heads has been used to reconstruct locomotor behavior in fossil hominins, but few studies have provided detailed empirical data to validate the assumed link between morphology and function at the MTPJs. ![]() In contrast, chimpanzees are believed to possess MTPJ morphology that precludes high dorsiflexion excursions during terrestrial locomotion. Particular features of metatarsal head morphology such as “dorsal doming” are thought to facilitate this stiffening mechanism. You can check out nuggets of wisdom like this one, along with interviews, bizarre uses for lightsabers, and more, each week on Up at Noon with everyone's favorite jokey boys Max and Brian.During bipedal walking, modern humans dorsiflex their forefoot at the metatarsophalangeal joints (MTPJs) prior to push off, which tightens the plantar soft tissues to convert the foot into a stiff propulsive lever.
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