Your dentist knows a lot about your diet and your habits just by examining your teeth. Evolutionary scientists value teeth too, but their interest lies in the potential of fossil teeth as biomarkers, a record of species development. Infant teeth are especially important because they provide a clear record of weaning patterns, and weaning patterns are important indicators of species development. **Professor Tanya Smith** analyzed infant fossil teeth to reconstruct the weaning patterns of Neanderthal and early humans. In this video, _Science for the Public_ visits Dr. Smith's lab to learn what makes fossil teeth great evolutionary biomarkers. We examine some ancient teeth and record a demonstration of the advanced technology that makes an accurate analysis of ancient teeth possible. Dr. Smith also explains the significance of this type of research.