The comparative anatomy and evolution of the mammalian larynx

Research Group

Behavioural Ecology Research Group (BEEC)

Proposed supervisory team

Dr Jacob Dunn

Theme

Evolution, Anatomy, Geometric Morphometrics, Communication, Language

Summary of the research project

Spoken language is one of the most distinctive characteristics of our species. Yet, our understanding of the evolution of this quintessentially human trait is far from complete. The dominant approach for the last few decades has been the search for fossil evidence of variation in vocal anatomy. However, most anatomical traits associated with speech are soft tissues, which do not fossilise, making it very difficult to establish when speech first evolved. This line of enquiry has diverted attention away from alternative questions that are equally interesting and more accessible empirically. In particular, it is probably more important to ask how and why specific anatomical changes for human speech took place. These questions can be addressed by applying the “comparative model” – using data from living species to shed light on the anatomy and behaviour of extinct species and reconstruct evolutionary scenarios.

Our research focuses on the comparative anatomy of the larynx and hyoid bone (the only bone in the larynx) in mammals. Evidence suggests that there were important shifts in the size and shape of the larynx and hyoid during hominin evolution and there appears to be a correlation between the morphology of the hyoid and the presence and size of air sacs in the larynx. Air sacs are air-filled cavities which are attached to the larynx in many primates, including all non-human apes, but, intriguingly, are absent in modern humans. They are thought to play a role in loud calls and are probably not necessary for the type of quiet vocal interaction that typifies human conversation. This suggests that the evolution of the modern human hyoid is associated with the loss of air sacs and, by extension, of loud calls. Hyoids are possible to find in museum collections, and their size and shape is easy to quantify using geometric morphometric methods. Larynges are much harder to source, as soft tissues are much rarer in collections. However, over the last three years we have worked closely with collaborators in Austria and Japan to build and scan a large collection of larynges. Thus, we are uniquely positioned to carry out research into this topic.

This project would analyse the size and shape of the larynx in one or more mammalian orders to model the evolutionary process. Laboratory and desk-based approaches would be necessary, potentially including CT scanning, geometric morphometrics, analysis of histological data and phylogenetic comparative methods. However, the exact nature of the project would be open for discussion and development with the candidate – in line with their skills and interests.

Interested candidates should contact Dr Jacob Dunn to discuss project ideas. Please note that this is currently a self-funded project.

Where you'll study

Cambridge

Funding

This project is self-funded.

Details of studentships for which funding is available are selected by a competitive process and are advertised on our jobs website as they become available.

Next steps

If you wish to be considered for this project, you will need to apply for our Biology PhD. In the section of the application form entitled 'Outline research proposal', please quote the above title and include a research proposal.