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Having spent some time considering subterranean mammals, my focus recently moved upwards. Professor Brock Fenton from the University of Western Ontario had put together an interdisciplinary team to make micro-CT scans of the heads of rare, preserved bats from the collection of the Royal Ontario Museum in Toronto; my summer student Kirsty Brain and I helped with their interpretation. We were interested in the hyoid apparatus, a chain of tiny bones which helps to support the larynx. In those bats which echolocate, we found that the hyoid apparatus includes a long element called the stylohyal which is connected to and in many cases is fused with the tympanic bulla, housing the middle ear. In non-echolocating fruit bats, there is no such connection. We suggested that the connection between the larynx where echolocation signals are produced and the middle ear might be no coincidence and that vibrations might thus be communicated to the ear to provide the bat with information about the sound that it was making, perhaps for comparison with the returning echo. The results of our study were recently published in Nature issue 463, and have been generating some interest among bat experts, including palaeontologists who hope to establish whether bats known only to us as fossils might have been able to echolocate. So what next? I have recently been considering mammals as a whole, from aardvarks to zebras, looking at the morphology of their middle ears and trying to interpret functionally the structural patterns that I have identified. The collegiate structure of the University has proven to be invaluable in allowing me to discuss ideas and form collaborations with mathematicians, engineers and other academics from diverse disciplines, as well as providing me with a steady stream of enthusiastic student volunteers. I am often asked (usually by medic s) what we gain from studying hearing in animals like moles. Perhaps this is not as glamorous as drug discovery or molecular genetics, but some years ago a Christ’s College graduate thought it worthwhile to pursue the study of earthworms, including experimenting on their responses to ground vibrations. ‘The subject may appear an insignificant one,’ wrote Mr Darwin, ‘but we shall see that it possesses some interest’. That’s the way I look at it too. Dr Matthew J Mason Acknowledgements I thank Alan Heaver of the Department of Engineering for his help with the microCT scanning which yielded the images for Figures 2 and 3. Space does not permit me to thank my other collaborators individually, but my website http://www.pdn.cam.ac.uk/staff/mason_ma/ gives more details of the published work that I have referred to in this article, and the people who made this possible.
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