Start Date
April 2026
Location
2nd floor - Library
Abstract
The evolution of the human foot maintains key adaptations that allow for efficient bipedal walking. A concert of morphological features distinguishes the human foot from that of both extant non-human primates and extinct hominin ancestors. This study explores the evolutionary significance of features like the foot arches, hallux alignment, and toe length and how these traits relate to locomotor efficiency. Particular focus was placed on the mechanical advantage of the muscles in the plantar-flexor system, which is directly modulated by toe length and calcaneal robustness. Mechanical advantage calculation allows for an estimation of push-off force that a particular plantar-flexor system is able to generate. To measure the mechanical advantage of—Human, Homo neanderthalensis, Homo floresiensis, Homo naledi, Ardipithecus ramidus, Chimpanzee, and orangutan—systems, length measurements were taken (in mm) of the in-lever (from the achilles tendon attachment point of the calcaneus, to the mid-portion of the tibiotalar joint) and the out-lever (from the distal most digit, to the mid-portion of the tibiotalar joint). The mechanical advantage is then calculated by taking the ratio of in-lever to out-lever (Li/Lo). Results showed that the mechanical advantage of the human plantar-flexor system is greater than that of extant great ape relatives and extinct hominin ancestors, with extinct hominin ancestors displaying a mechanical advantage less than, but more comparable to humans. These findings support the hypothesis that humans would display a greater mechanical advantage when compared to their extinct relatives in the genera Homo and Australopithecines, and the extant great apes.
The Human Foot and Bipedalism: Evolutionary Adaptations for Efficient Upright Locomotion
2nd floor - Library
The evolution of the human foot maintains key adaptations that allow for efficient bipedal walking. A concert of morphological features distinguishes the human foot from that of both extant non-human primates and extinct hominin ancestors. This study explores the evolutionary significance of features like the foot arches, hallux alignment, and toe length and how these traits relate to locomotor efficiency. Particular focus was placed on the mechanical advantage of the muscles in the plantar-flexor system, which is directly modulated by toe length and calcaneal robustness. Mechanical advantage calculation allows for an estimation of push-off force that a particular plantar-flexor system is able to generate. To measure the mechanical advantage of—Human, Homo neanderthalensis, Homo floresiensis, Homo naledi, Ardipithecus ramidus, Chimpanzee, and orangutan—systems, length measurements were taken (in mm) of the in-lever (from the achilles tendon attachment point of the calcaneus, to the mid-portion of the tibiotalar joint) and the out-lever (from the distal most digit, to the mid-portion of the tibiotalar joint). The mechanical advantage is then calculated by taking the ratio of in-lever to out-lever (Li/Lo). Results showed that the mechanical advantage of the human plantar-flexor system is greater than that of extant great ape relatives and extinct hominin ancestors, with extinct hominin ancestors displaying a mechanical advantage less than, but more comparable to humans. These findings support the hypothesis that humans would display a greater mechanical advantage when compared to their extinct relatives in the genera Homo and Australopithecines, and the extant great apes.
