Abigail Nishimura

The human neck is derived from those of the great apes in ways that are adaptive for upright bipedal locomotion. Human upright neck posture minimizes the effort required to hold the head above an upright trunk, and the decoupling of neck from trunk mobility is thought to compensate for front-to-back head pitching during bipedal running. Studies of neck evolution can clearly inform our understanding of human cranial shape, locomotion, and posture. Currently, however, hominin neck research is constrained by a lack of comparative experimental data and advanced phylogenetic analyses. Without this information defining form-function relationships in the neck, paleoanthropologists can only describe hominin necks as “human-like” (vertical and mobile) or “ape-like” (horizontal and immobile). These categories likely obscure meaningful functional variation, and they do not correspond to the diverse forms of bipedalism observed in the hominin fossil record. The goal of this dissertation is to improve hominin neck reconstructions by explicitly testing the form-function relationships linking cervical vertebral shape to neck mobility and neck posture. Using experimental and macroevolutionary approaches in comparative mammalian samples, this project will result in systematic interpretations of hominin neck function, data that can inform debates about the nature of hominin locomotor evolution.