Doctoral Dissertation Research: Evolution and development of the hominoid spine

Humans have many unique adaptations among primates, including the hallmark feature of bipedalism (walking on two legs) that shapes the way we move and how we design our built environment. The origins of bipedalism, including selective pressures and developmental changes that led to bipedalism, are not well understood. This dissertation project investigates the role of spine development in primates and mammals to better understand the way that spine evolution led to bipedalism. Project data will be used to expand and create museum exhibits about the origins of hominid bipedalism and evolutionary developmental biology in the Penn State Matson Museum of Anthropology. Science outreach activities will also be conducted through Penn State's Center for Science in the Schools, to bring STEM research experiences to underserved K-12 student populations. The project will also support training and mentoring of female undergraduate students in anthropological and developmental laboratory techniques, and provide opportunities for these students to present at conferences and co-author papers.

The thoracolumbar spine is crucial for understanding primate evolution and the origins and unique adoption of human bipedalism. Both great apes and humans have stabilized their spine with the posterior shift of the transitional vertebra and reduction of non-ribbed lumbar vertebra. There is debate regarding whether these features are homologous or homoplastic, and thus whether bipedalism evolved from a short stiff back like great apes or a longer lumbar column more similar to monkeys and Miocene hominoids. The investigators propose to compare the morphology of the primate transitional vertebra in museum collections and experimentally modified mice. Quantitative and qualitative analyses will be conducted on primate museum specimens and Hox9 modified mouse thoracic and lumbar columns using 3D and micro-CT scanning and a large osteological dataset. These analyzes will address two important questions: 1) whether patterns of the thoracolumbar transition are similar across apes, and 2) the developmental independence of various thoracic and lumbar vertebral features. Both are necessary for resolving debate regarding the evolution of the spine in hominoids.