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| Earth on Apr 08, 2012

Animals’ teeth reveal what they eat

Teeth from animals that eat hard foods having rougher surfaces than those that eat soft foods.

An animal’s teeth is literally shaped by its food. That’s according to new research from the Department of Geology at the University of Leicester, published in the Royal Society journal Interface. The research shows that the roughness of tooth surfaces can reveal what an animal has been eating. Teeth from animals that eat hard foods having rougher surfaces than those that eat soft foods. Use of evidence from teeth provides a new way to work out the diets of wild animals without involving the unpleasant task of looking at the contents of their guts.

Scientists say it is also possible to use these methods to investigate diets of extinct animals such as giant marine reptiles and dinosaurs.

Teeth of a tiger shark. Image Credit: Stefan Kühn

An international team of palaeontologists and biologists conducted this study, which showed that there is a close match between roughness of teeth and diet.

The teeth of haplochromine cichlid fishes that eat algae in different ways have very different tooth wear. The teeth on the top row are from fish that scrape algae from plants; those in the middle row are the same species, but scrape algae from rocks. The roughest teeth, those on the bottom row, are from a species that specializes in rock scraping. Image Credit: Mark Purnell, University of Leicester

Mark Purnell, Professor of Palaeobiology at the University of Leicester, said in an April 3, 2012 press release:

Run your tongue over your teeth. Some may feel rougher than others. The question we are trying to answer is can the roughness of the tips of teeth, worn by contact with food, be used to work out what an animal has been eating?

But before we can start to answer that question, we need to ask is what is roughness? This is tricky to measure. Smooth and rough surfaces are intuitively easy to distinguish, but is tree bark rougher than a road surface? Is the microscopic surface of chalk rougher than cheese? It’s hard to make the comparison.

But the question does matter. For example, as hip replacements wear, do they get rougher or smoother? If an engine cylinder is too smooth it won’t retain enough oil on its surface, leading to friction and seizing, but how smooth is too smooth? In order to answer questions like this, engineers have been working on ways to measure roughness for decades. International standards are now being developed, based on new ways of measuring surfaces very precisely using special 3-D microscopes, and it is this approach that has been applied to the teeth in this study.

The scientists said their new method for studying teeth provides a useful new way of investigating fish diets – for example, researching how changes in diet control the disappearance of species, or the evolution of new ones – and will be especially useful in analysis of fossils, the diets of which are hard to determine.

The teeth of an alligator. Image Credit: Didier Descouens

Lion's teeth. Image Credit: Siemdepiem

Human teeth. Could the method used by scientists to determine an animal's diet via its teeth also be used to see what you or I eat? Image Credit: SuperFantastic

Ole Seehausen, the team member responsible for identifying stomach contents, added:

To our surprise, we found that in some cases tooth roughness is a more reliable guide to diet than looking in a fish’s stomach, because stomach contents tell you only what an animal was eating in the few hours before it was caught, not what it usually eats.

Bottom line: The roughness of an animals teeth reveals what its diet consists of, according to research from the University of Leicester, published in the Royal Society journal Interface. Use of evidence from teeth provides a new way to work out the diets of wild animals without involving the unpleasant task of looking at the contents of their guts. It might also be possible to use these methods to investigate diets of extinct animals.