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Shedding New Light on What We Eat

By Nina Simon '03

Graduate student Torbjorn Bergstrom '95 uses the sophisticated imaging and analysis technology of WPI's Surface Metrology Laboratory to study microscopic wear patterns on teeth. The abrasions provide clues to the diet and lifestyle of animals. The three images below, consisting of photomicrographs, taken with a white-light confocal microscope, and 3-D coordinate maps of the dental surfaces, show the results of tests done on teeth of, from left, the bushbuck, which browses in dense riverine bush or forests, the blue wildebeest, which grazes in open savanna or grassland, and the brown capuchin, which dines on the hard seeds and pits from palm fronds.

Tragelaphus scriptus

Connochaetes taurinus

Cebus apella

When people think of sciences like archeology or biological anthropology, many of them think big: teams of scientists surrounded by enormous excavations in the desert. But much of the fascinating research being done in anthropology--or, more specifically, paleoanthropology or human paleontology--addresses minutiae and occurs in laboratories rather than sun-swept dunes. Indeed, some of the smallest, and most revelatory, parts of the fossil record are teeth. Teeth provide a track record of lives and habits. They hold the secrets to what species ate, when their eating patterns changed, and how the environment affected their diet.

Professor Christopher Brown and graduate student Torbjorn Bergstrom '95, working in WPI's Surface Metrology Lab, are examining an even smaller component of the fossil record: the microscopic marks left on teeth by different foods. To the naked eye, it is impossible to discern the subtle features of a fossilized tooth that indicate what its owner ate, and by extension, how it behaved. But thanks to today's most advanced microscopic imaging techniques, tiny abrasions and perturbations known as dental microwear magnify into a landscape of fossilized clues from which ancient diets may be understood.

Brown and Bergstrom's focus has been on creating quantitative standards by which dental microwear researchers can measure what those landscapes reveal.

Why is quantitative analysis important? Traditionally, dental microwear researchers have obtained images of tooth surfaces using the scanning electron microscope (SEM). The technique produces high-quality images, but does not yield results that lend themselves easily to standardized quantitative analysis. Instead, scientists have had to identify and measure tooth surface marks by hand, a time-consuming, subjective and inconsistent method. Scientists may describe and count the demarcations on teeth, but there is little reliability in how they define, say, a scratch or a pit. One person's mountain is another's molehill, and objective consistency loses out.

Furthermore, Brown says, "there are important applications in manufacturing that can come from this research. As we go further in developing technology for bioengineering, micro-electro-mechanical systems devices and nano-fabrication surface textures, their measurement and analysis become increasingly important."

In this National Science Foundation-funded project, Brown and Bergstrom are collaborating with researchers in the University of Arkansas Anthropology Department to develop ways to add quantifiable, three-dimensional information via a two-step imaging and analysis process.

First, the dental surfaces are imaged with white-light confocal microscopy, an innovative technology that produces high-resolution images comparable to those of the SEM but that also generates 3-D coordinate maps of the dental surfaces. Then, the maps are quantitatively analyzed using variations of the scale-sensitive fractal analysis (SSFA) software protocols that Brown and Bergstrom originally developed for applications in manufacturing engineering. SSFA software scans the confocal microscopy images and measures microwear by recording marks on the dental surface in three dimensions. The WPI software alleviates microwear researchers' dependence on the human eye for analysis, thus yielding accurate, repeatable information about the marks.

As this new technology spreads through the research community, it is hoped that dental microwear paleontologists worldwide will be better equipped to uncover the secrets revealed, micron by micron, in the pits and scratches of teeth.

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Last modified: Sep 13, 2004, 15:33 EDT
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