Paper, Stiffness of the human foot and evolution of the transverse arch
The stiff human foot enables an efficient push-off when walking or running, and was critical for the evolution of bipedalism1,2,3,4,5,6. The uniquely arched morphology of the human midfoot is thought to stiffen it5,6,7,8,9, whereas other primates have flat feet that bend severely in the midfoot7,10,11. However, the relationship between midfoot geometry and stiffness remains debated in foot biomechanics12,13, podiatry14,15 and palaeontology4,5,6. These debates centre on the medial longitudinal arch5,6 and have not considered whether stiffness is affected by the second, transverse tarsal arch of the human foot16. Here we show that the transverse tarsal arch, acting through the inter-metatarsal tissues, is responsible for more than 40% of the longitudinal stiffness of the foot. The underlying principle resembles a floppy currency note that stiffens considerably when it curls transversally. We derive a dimensionless curvature parameter that governs the stiffness contribution of the transverse tarsal arch, demonstrate its predictive power using mechanical models of the foot and find its skeletal correlate in hominin feet. In the foot, the material properties of the inter-metatarsal tissues and the mobility of the metatarsals may additionally influence the longitudinal stiffness of the foot and thus the curvature–stiffness relationship of the transverse tarsal arch. By analysing fossils, we track the evolution of the curvature parameter among extinct hominins and show that a human-like transverse arch was a key step in the evolution of human bipedalism that predates the genus Homo by at least 1.5 million years. This renewed understanding of the foot may improve the clinical treatment of flatfoot disorders, the design of robotic feet and the study of foot function in locomotion.
Learn about our two Decals!
Click here to find out more about our Fall Bioinspired Design Decal and our Spring Bioinspired Design in Action Decal – ALL MAJORS are welcome.
Berkeley BioDesign Community
Click here to learn about the BioD: Bio-Inspired Design @ Berkeley student organization or here to signup for more info.
Search
Student Login
I imagine that the neurological circuits underlying these processes are governed by both 2d spacing maps with their brains as…
to reduce the impact of car accidents, it may be possible to study the force diverting physics of cockroaches to…
you see this type of head-bobbing stability in many avian creatures related to pigeons like chickens. the head ability to…
not like they taught horses how to run! this is an example of convergent evolution where both sea creatures and…
The brain functions in a similar way with neuronal connections. our brains are able to utilize the multiplicity of connections…