Collaborative Research: Experimental assessment of dental microwear formation

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It is widely understood that the evolution of hominins was strongly influenced by diet, and yet there continues to be a debate about precisely which types of foods were eaten by them. In particular, it is unclear whether the massive jaws and huge teeth of these early humans evolved to process hard foods like nuts and seeds, or tough, fibrous foods that might have included grasses. An important piece of evidence in this debate comes from the microscopic damage done to teeth by food, and particles of grit that may adhere to food. This study conducts experiments designed to evaluate how patterns of such microscopic damage should be interpreted in order to reconstruct diet in fossil humans. This study will have broad implications, including 1) improving our understanding of why humans evolved, 2) evaluating established methods, and developing new methods, of reconstructing diet in extinct animals, which in turn may influence our understanding of ancient environments and how they changed over time, and 3) providing an experimental basis for interpreting feeding behavior in both prehistoric and historic human populations. The project also supports the research of PIs at diverse career stages, including an early-career female researcher, as well as graduate, undergraduate, and volunteer high school students (in collaboration with local university and community programs like the Vanderbilt School for Science and Math). All students will receive mentoring in performing and communicating results of scientific research (high school students will also publish in the Young Scientist journal), professional development skills, and improving their ability and desire to implement research, education and outreach activities as future professionals.Experiments will use suid and ovid models to evaluate the effect on tooth surfaces of varying toughness and hardness of foods, as well as the hardness and size of abrasive particles like sand, seed shell fragments and other very hard plant parts. The microscopic damage done to teeth will be assessed using surface scans and nanomechanical force microscopy, and statistical methods will be used to determine whether foods, particles, or an interaction between them drives patterns of damage. This, in turn, will allow an evaluation of the causes of damage patterns seen in the teeth of fossil humans, which will in turn allow a more precise assessment of the diets of early humans. The damage on the teeth will then be assessed on a nano-scale in order to determine if a new method of dietary reconstruction can be developed based on a characterization of individuals wear marks.