 I'd like to invite to the stage Hannah James from the ANU College of Physical and Mathematical Sciences. The title of Hannah's presentation tonight is You Are Where You Eat. You've heard the phrase, you are what you eat. But I don't care about what you eat. What I'm interested in is where you eat. That is where people of the past ate because that tells us where they lived. Understanding where people lived and where they migrated is central to archaeology. And in my research, I'm looking at human remains from around the world and amazingly using teeth. I can identify where people ate and lived as a child. It all starts with the chemical elements, oxygen and strontium, and in particular the isotopes of these elements. Isotopes are just the different versions of an element which differ only by their weight. And what's cool about oxygen and strontium is different rainfall patterns and bedrock geology in a region leads to different amounts of each isotope. So regions have their own unique elemental signatures. The plants, animals and people in that region adopt this elemental signature from their food and water. So by comparing the value in a body tissue to a regional signature, we can see if someone is a local. My body tissue of choice is teeth. Teeth form in childhood and then never change. So they've locked in the signature of what you ate and where you lived as a child. If I were to jump down to the audience now and sample your tooth, take it back to the lab and analyse it. We could see if you're a Canberra local or if you moved here after childhood. If you moved during childhood, we may even be able to see when by comparing your front teeth around to your wisdom teeth which form at different times. This technique has forensic applications but I'm an archaeologist and I prefer to work with more ancient dead people. But measuring the teeth alone isn't enough. To understand migration, we need to be able to compare teeth to regional signatures which aren't always available. This is where my work comes in. I'm building maps of these regional elemental signatures with samples of rocks, soils and plants. Using chemistry and filters, we just separate out the elements we're interested in and then analyse and map them. I can then compare teeth from archaeological sites to these maps to create a picture of the movement of individuals and the makeup of communities in the past. I'm working on several case studies in the Pacific to explore the first migration of people into a previously uninhabited area. In France, to trace the seasonal migration of people about the landscape. And in the Caribbean, we're looking at a slave cemetery to understand the different generations of people within that population. By combining this new information with more traditional archaeology, we can build up a better picture of our own human past. So in the end, you aren't just what to eat, but more interestingly, you are where you eat.