A Microscopic Focus on Teeth
You usually do not think much about teeth. You brush them twice a day and use them to chew your food. But who would have thought that the texture of your teeth can tell scientists, now or give or take a few million years, what you primarily ate?
A researcher at the University of Arkansas, Peter Ungar devised a technique called microwear texture analysis. This upcoming winter and the following summer he and his colleagues will collect samples of dental molds from the Hadza people, modern hunter-gatherers in northern Tanzania, and compare the texture of those molds to samples of the human predecessors, hominins. If the technique is sensitive enough to discern between a meat-based diet and a tuber-based diet, he may be able to determine what hominins survived off of.
In the past, dental microwear, essentially the microscopic “wear and tear” on teeth, revealed only two-dimensional features. Ungar’s microwear texture analysis scans dental molds and reveals them in three-dimensions as a cloud of points. He said he expects the tuber-based diet to appear more complex and show larger surface features than the meat-based diet.
For dental molds to be usable for microwear texture analysis, the samples require proper cleaning to remove a micron-thin layer of organic matter on the surface. For this, Ungar uses surprisingly basic dental techniques.
“The methods for dental molding are the same as those used on dental patients in the United States, with an additional step for cleaning, and are entirely non-invasive,” Ungar said. “Teeth are cleaned with a toothbrush and non-toxic organic solvent solution. They are then dried with cotton balls and air from a portable compressor before molding. Standard dental trays and polyvinylsiloxane impression material will be used to make the molds.”
The dental molds will return to the University of Arkansas for the actual microwear texture analysis.
This will be the first time for researchers to analyze the microscopic wear on teeth from a meat-based diet versus a tuber-based diet. The winter sampling will include molds from teeth frequently subjected to tubers, a back-up source of food for the Hadza when game is scarce. The summer sampling will include molds from teeth often exposed to meat, the preferred food source.
I am having a hard time imagining how casts from our teeth can reveal so much about our diet, especially considering how a scientist can compare the teeth of living people to those who lived millions of years ago.