PhD: Understanding fossil footprint formation and the evolution of human locomotion on compliant substrates

The transition to terrestrial bipedalism represents a defining episode in the evolutionary history of our species. To understand how, when and why upright bipedalism evolved we have long relied on the shape of fossil footprints to diagnose the style of locomotion used by our ancestors. This is because modern human foot anatomy and function are considered defining “hallmarks” of our upright bipedalism: it is suggested that we possess stabilised arches in the mid-foot to impart the necessary stiffness to help generate the forces required to stride bipedally over the ground. This contrasts with tree-dwelling non-human apes like chimpanzees that have long toes and a highly mobile mid-foot to provide the necessary flexibility for grasping and climbing. Thus, for example, broadly human-shaped metatarsal bones would be seen as diagnostic of a stabilised mid-foot arch and subsequently as evidence for efficient upright terrestrial bipedalism in a human ancestor. The same conclusion would be drawn in the case of a broadly “human-shaped” fossil footprint.

However, recent biomechanical research has suggested that the link between foot bones, footprint morphology, and locomotion may not be so straightforward. For example, a number of recent studies have shown not only high levels of variation within modern humans, but that a number of individuals use a very “stiff” (i.e. stereotypically human) midfoot in some steps, but a very “flexible” (i.e. stereotypically non-human ape) midfoot in other steps. How these different motions are reflected in the shape of footprints is completely unclear. This indicates that a much more detailed understanding of how morphology links to function in modern humans is necessary to understand locomotion in hominid fossils, and subsequently how, when and why upright bipedalism first evolved. Deriving and applying this new mechanistic understanding is the goal of this project.

In this project, the student will assess the relationship between lower limb anatomy, locomotor biomechanics and 3D footprint shape in humans. This approach will be predominantly experimental, combining 3D reconstructions and measurements of lower limb anatomy from medical imaging techniques (CT/MRI) with 3D gait and motion analysis. However, there is also potential for work involving computer simulations techniques. The project will make use of the state-of-the-art biomechanics facilities within the Institute of Ageing & Chronic Disease at the University of Liverpool. This include a large purpose-built gait lab containing 3D motion capture systems, force and pressure plates, isokinetic tester, EMG & accelerometer equipment, pressure insole system and material testing facilities. In addition to these experimental facilities we also have direct access to medical imaging (MRI, CT) and high-performance computing facilities to support computer simulation approaches (MDA, FEA).

The student will have a keen interest or background in anatomy, biomechanics and evolution and skills in quantitative, mechanical and/or 3D digital techniques, but we will provide training in all techniques to be used. The team that the student will join includes experts in vertebrate anatomy, biomechanics, imaging and computer simulation. You’ll be based primarily with Dr Karl Bates in the Evolutionary Morphology & Biomechanics Group at Liverpool.

Relevant publications:
- D'Aout, K., Meert, L., Van Gheluwe, B., De Clercq, D., & Aerts, P. (2010). Experimentally Generated Footprints in Sand: Analysis and Consequences for the Interpretation of Fossil and Forensic Footprints. American Journal of Physical Anthropology, 141: 515-525.
- Bates, K.T., Savage, R., Pataky, T.C., Morse, S.A., Webster, E., Falkingham, P.L., Ren, L., Qian, L., Collins, D., Bennett, M.R., McClymont, J. & Crompton, R.H. 2013. Does footprint depth correlate with foot motion and pressure? Journal of the Royal Society Interface. doi: 10.1098/rsif.2013.0009.
- Bates, K.T., Collins, D., Savage, R., Webster, E., Pataky, T.C., McClymont, J., D’Aout, K., Sellers, W.I., Bennett, M.R. & Crompton, R.H. 2013. The evolution of compliance in the human lateral mid-foot. Proceedings of Royal Society B 280(1769): 20131818.
- Falkingham, P.L. & Gatesy, S.M. 2014. The birth of a dinosaur footprint: Subsurface 3D motion reconstruction and discrete element simulation reveal track ontogeny. Proceedings of the National Academy of Sciences of the United States of America, 111: 18279-18284.

Funding notes and specific eligibility requirements:
This project is funded by the Leverhulme Trust as part of a three-year grant. This funding will fully cover the cost of the standard tuition fees for three years for individuals that qualify as UK resident PhD students, and provide the student with a stipend of £12,725.01 per year for those 3 years. Additional funding is available in the grant for research costs, travel and conference attendance.