Human: Phylogeny

The 4th metatarsal is considered to be one of the key clues for determining whether a species is bipedal or not. Some characteristics of this bone (torsion, orientation of the ends of the bone) are associated with longitudinal and transverse arches in the foot, which are known to support upright walking. This set allows one to examine the metatarsals of the modern human, A. afarensis, chimpanzee, and gorilla. Some suggest that the A. afarensis metatarsal shares significant similarities with the modern human.