12:15 pm
KPTC Room 206
"Geometry and mechanics of feet and fins"
Feet look quite different from fins but face the same structural demand to be sufficiently stiff in order to withstand the forces of propulsion. In this talk, I will show that curvature-induced stiffness is the common principle underlying the stiffness of both primate feet and rayed fish fins. The principle is evident in a drooping currency note or slice of pizza that significantly stiffens upon slightly curling it along the width. We use mathematical analysis, physical mimics, and biological experiments to derive the relationship between curvature and stiffness, and apply this understanding to track the evolution of foot curvature among hominins (human lineage). I will also show how the same principle manifests in fish fins despite their different morphology, with implications for the 380 million year old water-to-land evolutionary transition among vertebrates.