Dental Analysis for Dietary Reconstruction

古人类学家试图了解人类祖先的饮食适应，研究现代非人类灵长类动物，以确定牙齿结构和功能之间的联系。牙釉质是牙齿坚硬的外层覆盖物，是牙齿解剖学中最受关注的方面之一，因为它与食物直接相互作用。本研究探讨了灵长类动物的牙釉质厚度和结构如何在短时间内发生变化，这与饮食和牙齿功能的特定方面有关。为了实现这一目标，这项研究利用了俄亥俄州立大学收藏的灵长类动物骨骼，包括来自不同野外地点的旧大陆猴子骨骼。与这些骨骼遗骸相关的饮食和牙齿使用数据为研究现存灵长类动物的牙釉质变化与饮食和口腔加工行为的关键特征之间的关系提供了机会。由于这项工作，将提供大量灵长类动物的微ct扫描（约400颗牙齿）和组织学切片（60-80颗牙齿），从而加强研究和教育的基础设施。本科生参与和培训这个项目有助于STEM劳动力的发展。通过俄亥俄州立大学人类学公共推广计划传播项目发现将增加公众对科学和技术的参与。最后，这项研究与一个地方项目有关，该项目对社区成员有环境、健康和教育方面的好处。这个项目填补了古人类学家对牙釉质如何随着饮食和口腔加工行为的特定方面而进化的理解的空白。目前，灵长类动物的厚牙釉质表现出一种模糊的功能信号，表明它们适应坚硬和/或磨蚀性的饮食。本研究探讨了牙釉质厚度分布的各个方面以及牙釉质棱柱与牙齿磨损面形成的角度是否与硬物摄食（即硬噬）有关，可能为推断化石物种对硬噬的适应提供依据。更令人困惑的是，对牙釉质厚度的古人类解释是，牙釉质厚可能意味着适应了习惯性的硬食，或者只在没有软食物的时候才吃硬食物，这是一种所谓的“退步”进食策略。这项工作更全面地评估了灵长类动物的牙釉质厚度，这些灵长类动物是习惯性的硬食物消费者和退化的硬食物消费者，询问牙釉质厚度分布和/或牙釉质棱镜方向是否与这两种适应有关。此外，研究属于不同进化谱系的物种的厚牙釉质的潜在发育差异，阐明了牙釉质在短进化时间内进化能力的发育途径。最后，先前的研究表明，在食叶灵长类动物中，对薄牙釉质的选择限制了牙釉质的进化；本项目使用饮食差异很大的食叶灵长类动物样本更全面地评估了这一建议。总之，对这些相关问题的研究阐明了选择压力对牙釉质整体厚度、牙釉质厚度分布和牙釉质结构的影响，为这些特征的进化和限制提供了见解。反过来，这些见解将为从牙釉质中收集到的关于饮食适应的古人类推断奠定更坚实的基础。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Paleoanthropologists who seek to understand dietary adaptations in human ancestors study modern non-human primates to identify links between dental structure and function. Enamel, the hard, outer covering of a tooth, is one of the most scrutinized aspects of dental anatomy because it interacts with food directly. This research explores how the thickness and structure of tooth enamel, which appear to change over short evolutionary time periods, relate to specific aspects of diet and tooth function in primates. To achieve this goal, this research leverages a collection of primate skeletons housed at The Ohio State University, consisting of Old World monkey skeletons from various field sites. Data on diet and tooth use associated with these skeletal remains provides opportunities to investigate how enamel variation in living primates relates to critical features of their diets and oral processing behavior. As a result of this work, a large collection of microCT scans (~ 400 teeth) and histological slides (60-80 teeth) of primates will be made available, thus enhancing infrastructure for both research and education. Involvement and training of undergraduates in this project contributes to the development of a STEM workforce. Communication of project findings via The Ohio State University's Anthropology Public Outreach Program will increase public engagement with science and technology. Finally, this research is associated with a local project, which has environmental, health, and educational benefits to community members.This project fills gaps in paleoanthropologists’ understanding of how enamel evolves in response to specific aspects of diet and oral processing behavior. Currently, thick enamel in primates presents an ambiguous functional signal, suggesting adaptation to hard and/or abrasive diets. This research investigates whether aspects of enamel thickness distribution, and the angles that enamel prisms make with tooth wear surfaces, are associated with hard-object feeding (i.e., durophagy), potentially providing a basis for inferring adaptation to durophagy in fossil species. Further confounding paleoanthropological interpretation of enamel thickness is that thick enamel may signify adaptation to either habitual durophagy or to the consumption of hard foods only during periods when softer foods are not available, a so-called “fallback” feeding strategy. This work more fully assesses enamel thickness in primates that are habitual vs. fallback hard-food consumers, asking whether there are differences in enamel thickness distribution and/or enamel prism orientation related to these two adaptations. Additionally, investigating potential developmental differences in the thick enamel of species that belong to different evolutionary lineages elucidates developmental pathways underlying enamel's ability to evolve over short evolutionary time spans. Finally, previous studies have suggested that in leaf-eating primates, selection for thin enamel constrains the evolution of enamel; this project more fully assesses this suggestion using a sample of leaf-eating primates with wide dietary variation. Altogether, research into these related questions elucidates selection pressures shaping overall enamel thickness, enamel thickness distribution, and enamel structure, providing insight into evolvability and constraint in these features. In turn, these insights will form a more robust foundation for paleoanthropological inference about dietary adaptation gleaned from tooth enamel.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.