Australian archaeologists* are using koala teeth and bones to create a map that will show how people and animals moved across the continent through history.
Because koalas mostly stay in one place and only eat leaves, the chemical makeup of their teeth and bones give a clear picture — like a geographic* signature or fingerprint — of exactly where they have lived, even if their remains were later moved to another place.
Flinders University senior lecturer Dr Ian Moffat explained that the rocks and soils of a place are responsible for chemical markers — called isotopes — in living things.
“All animals including people take up, from the food they’re eating and the water they’re drinking, the isotope composition of the local geology*,” he said.
Different isotopes are slightly different versions of the same element. The scientists looked at different versions of the element strontium, a metal found in tiny quantities in soil, water and food and that then makes its way into the bones and teeth of animals that eat that food or drink that water.
“You and I that ate wonderful cheese from the Adelaide Hills or wine from Tasmania and apples from Chile, so it’s a mix of everything, but for people from prehistory or for animals, they tend to source everything from the same area where they live.”
This knowledge, combined with chemical analysis of teeth and bones from koalas (and rats where koalas were not available), has been used to create Adelaide’s first “strontium isotope map”.
Mapping koala's chemical isotopes for archaeology
Koalas have one of the longest fossil records of any of Australia’s modern marsupials, dating back at least 24 million years. They became extinct in South Australia following colonisation but were successfully reintroduced to the mainland after 1959.
The project is a first for South Australia and the first time koalas have been used to do the job, but probably not the last. That’s because, Dr Moffat said, they are perfectly suited to the task, “like a custom designed isotope mapping machine”, because they don’t drink water. They get all they need from eating gum leaves, so there’s no confusion between isotopes from these plants, growing in the soil, and isotopes from the water flowing from elsewhere down a creek or river.
“As koalas don’t move much, they have a really local signature and because they’re not drinking water, you just get stuff from that place where they live, so there really is no better animal for doing isotope mapping with,” Dr Moffat said.
Now the scientists want to expand the area and create an isotope map for the whole of Australia. It’s a way of linking archaeological artefacts to the area from which they came, using the chemistry of the rocks and soil, which, in turn, allows archaeologists to track how people moved across the landscape over time.
The research is published in the Journal of Archaeological Science.
- archaeologists: experts in human prehistory and history
- geographic: relating to the physical features of a landscape
- geology: science of the physical structures and substances of the Earth, such as the rocks
- What is this story about?
- Why use koalas for this project?
- What substance in the koala teeth and bones are they studying?
- Where does Dr Ian Moffat work?
- Where have the archaeologists published their research?
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1. Write a Thank You Letter
Write a letter to Dr Ian Moffat. The purpose of your letter is to thank him for his work on isotope mapping using koalas. Your letter should include explaining why you think his work is so important and some of the most interesting things about his research.
Time: allow 20 minutes to complete this activity
Curriculum Links: English, Science, Critical and Creative Thinking
Do you think that scientists of the future will be able to create the same kind of isotope maps from people and animals living today? Give reasons for your answer.
Time: allow at least 20 minutes to complete this activity
Curriculum Links: English, Science
Grammar and VCOP
The glossary of terms helps you to understand and learn the ambitious vocabulary being used in the article. Can you use the words outlined in the glossary to create new sentences? Challenge yourself to include other VCOP (vocabulary, connectives, openers and punctuation) elements in your sentence/s. Have another look through the article, can you find any other Wow Words not outlined in the glossary?
HAVE YOUR SAY: Archaeology is the study of human history. What archaeology project would you choose?
No one-word answers. Use full sentences to explain your thinking. No comments will be published until approved by editors.