New study ties tooth wear in fossils to diet, validating decades of research

Dental wear is among the top techniques scientists use to reconstruct and analyze dietary patterns of human ancestors and animals. Researchers recently questioned the validity of tooth-wear analysis, however, stating that environmental elements such as grit on food was likely responsible for wear.

"This challenge has led paleontologists to question decades of results," said Peter Ungar, distinguished professor and chair of the University of Arkansas Department of Anthropology. "Our findings validate the use of tooth wear for understanding diet of fossil animals. What does this tell us about diet? That habitat doesn't necessarily skew dental wear data."

Ungar worked with Ryan Tian, U of A professor of chemistry, and researchers at the Tribology Research Institute at Southwest Jiaotong University in China to verify the tie between tooth wear and diet.

The Proceedings of the National Academy of Sciences published the findings this month.

"We found that materials softer than enamel can wear teeth," Ungar said. "This allowed us to develop a whole new way to model tooth wear.."

Ungar explained that enamel is made up of particles bonded together by a protein glue. He and the team found through experiments that as chewing occurs, those bonds break and tiny enamel particles break away from teeth.

This finding validates the long-held premise that tooth wear can be related to specific types of diets and environments.

For example, scratches on fossilized teeth indicate a shearing chewing motion used with tougher meats and plant-based diets. Pits in teeth indicate a hard and brittle natural diet such as animal bones or nuts.

"We determined that microwear is not just about grit in the environment," Ungar said. "There certainly can be a diet component to it."

The team's discovery opens the door to study the properties of other materials.

"What Mother Nature does in tooth enamel encourages us to revisit known theories in nanocrystal science, polymer, composite, biomineralization, self-assembly and surface science," Tian said.