The vertebral column stabilises the body, facilitates flexion/extension of the back and serves as the axis of a basic tetrapodal body plan that can be adapted to various forms of locomotion. It comprises five regions, each containing vertebrae of different shapes and sizes. In primates, there are almost always seven cervical vertebrae, with this number very stable except in rare (usually pathological) instances. In the other regions, however, the number of vertebrae varies more freely. Vertebral shape also varies within and between regions, from head to tail-tip. Knowing more about why and how vertebral variation develops in primates, and how these patterns of variation have evolved, would dramatically enhance our understanding of the complex structure and function of primate (including human) spines.

One potential cause of variation in primate vertebral columns is locomotion. Primates display several distinctive locomotive styles and can be arboreal or terrestrial. There has been recent debate as to how much locomotor styles and flexibility might drive functional variation in primate skeletons, but this mostly focuses on limb bones. As of yet, we remain uncertain even of how much variation there actually is in the primate vertebral column. Even less has been done on the potential role of locomotion as a driver of specifically intraspecific anatomical variation, although we know there is substantial within-species variation in locomotor behaviour. This project will quantify vertebral number variation across primate species and use digital photography to capture size and shape variation through all five regions. We will analyse vertebral morphometrics within individuals and within and between species. Ethical approval is not required for this data collection, as we will use only existing skeletons housed in major museums.

Our analyses will focus particularly on transitional vertebrae and the possibility that developmental constraints and histories might affect vertebral numbers, shapes and patterns in species with different locomotor preferences. We aim ultimately to deepen understandings of how and why variation occurs within a species, how the primate vertebral column has evolved, and how much variation there is within non-pathological primate populations