Silvia Pineda-Munoz looks at a gorilla's teeth and sees a complicated, rugged landscape: jagged peaks and rolling hills, deep valleys that swerve through the enamel. It reminds her of the Appalachian Mountains.
A carnivore's tooth, on the other hand, is like one of the volcanic islands that make up Hawaii. It rises up from the gums in a perfect cone, its sheer sides meeting at a dangerously sharp point.
Comparisons between mountain ranges and tiny teeth come naturally to Pineda-Munoz because she studies animals' mouths with a tool used by mapmakers: GIS, for geographic information system. The technology lets researchers take spatial and geographic data — whether it's the distance between cusps or between peaks — and then quantify and analyze it.
Pineda-Munoz, an evolutionary biologist at the National Museum of Natural History, has used GIS to create a database of mammal teeth. The pearly whites of more than 100 species are characterized via six measurable features that are related to food processing and give clues about an animal's diet. Each of those characteristics gets a number.
“It allows you to get a mathematical comparison,” Pineda-Munoz said. “A number that tells you how two teeth are alike or not.”
That way, when future biologists find themselves looking at an unfamiliar tooth — say, the incisor of an undiscovered species or the bicuspid of a now-extinct beast — they can easily look through the database and find something to compare it with.
Pineda-Munoz wasn't always obsessed with animal dentistry. She became a scientist with the aim of understanding evolution, a concept that has fascinated her from an early age. But her PhD adviser happened to study teeth, and she quickly fell under their spell, as well.
“They're an amazing tool to understand change and understand evolution,” she said.
Think about it. Warm-blooded mammals have fast metabolisms that require a lot of fuel. That means they need to find ways to extract maximum energy from their food with minimal effort.
“In order to have more energy, we have to process the food, we need to make sure it's well . . . chewed before we swallow it,” Pineda-Munoz said. Teeth are “the tools to do that.”
As any good craftsman knows, tools are better when they're specialized for the task at hand. That's why carnivores have sharp, blade-like teeth designed for ripping meat, while leaf-eaters have mortar-and-pestle-like molars that can grind up fibrous foods.
To figure out what foods were on the menu for ancient species, Pineda-Munoz hopes paleontologists will take a look at her database. “It will help them in assessing how animals’ teeth have evolved,” she said.