3D printing, teeth and human evolution

Dr Varsha Pilbrow spoke at March’s Skeptics Café. Dr Pilbrow is a Lecturer in the Department of Anatomy and Neuroscience at Melbourne University.

She specializes in the dental morphology of the living apes, and is currently working on international research projects in the study of fossil hominids and  in bioarchaeology, studying the physical anthropology of human skeletal remains from archaeological sites at the cross-roads of major human migration routes.

The presentation was introduced with a general discussion about the usefulness of teeth in this kind of research. They fossilize well, so there’s a lot of material about. They also have a fairly simple structure compared with other body tissue. It was also mentioned that teeth can be a viable source of DNA extending out to 100,000 years. However, the bulk of the presentation was concerned with variations in the shape of teeth that can be followed through fossil and living hominids.

Shape (morphological features) of teeth are under “strong genetic control“. It seems that mutations which produce changes in teeth shape don’t happen often or easily, but once they do, they become locked in as part of the evidence which can be used to investigate the phylogenetic relationships between hominids in the fossil record extending to the living apes – chimpanzees, gorillas, orang-utans and gibbons.

Terms like “shovel-shaped incisors” and “Carabelli cusps” were prevalent in Dr Pilbrow’s presentation, accompanied by appropriate illustration. These showed the kinds of morphological features (presence, absence, prominence) that can be used statistically to gauge degrees of affinity between known species.

Dr Pilbrow said that some unlikely early results might be explained by a biased practice of using humans as major reference sample rather than the current wider spectrum of hominids.

This sort of dental evidence is both useful and necessary, because postulated taxonomy for these animals has often been quite speculative, depending only on apparent similarities or differences in skull shape, for example.

Dr Pilbrow’s team at Melbourne University scan fossil teeth samples from museums around the world. These are then 3D printed and made available as reference material to other researchers in the field.

This talk was very well received, due to Dr Pilbrow’s enthusiasm for her subject and her ability to make key technical considerations accessible to the mostly “lay” people (and one token dentist) that comprised the audience.

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