Doctoral Dissertation Research: Abrasive foods, tooth size, and enamel thickness in primates

食用坚硬的磨蚀性食物可能导致了我们最早的人类祖先牙齿的关键变化。研究人员提出，在人类进化过程中，摄入对牙釉质具有磨蚀作用的颗粒是形成牙齿特征的重要力量，包括更厚的牙釉质和更大的牙齿尺寸。关于哪种磨料对理解人类牙齿的进化最为重要，存在着争论。这个博士论文研究项目调查了牙齿大小和牙釉质厚度是否随：(1)摄入研磨颗粒而变化，以及(2)灵长类动物在野外咀嚼食物的能力。该项目培训来自STEM领域和实验室方法代表性不足的背景的学生，其中一些导致独立的荣誉项目，并为K-12和博物馆教育推广做出贡献。该项目进一步促进了联合国教科文组织世界遗产地灵长类动物长期野外站的能力建设。这项研究的长期目标是为围绕灵长类动物觅食行为和牙齿特征之间的形式-功能关系的假设提供信息，这是推断人类化石记录中行为的重要任务。研究人员(i)区分和量化猴子饮食中的植物岩和砂砾，并将这种变化与（ii）粪便颗粒大小（咀嚼性能的度量）的变化进行比较；（iii）从特定人群骨骼收集的牙齿大小和牙釉质厚度的差异。该项目利用灵长类动物牙齿生态学中建立和新兴的技术来解开一个长期存在的难题。磨牙大小和牙釉质厚度是古人类学家长期以来的重要特征，是系统发育重建和饮食推断的核心，但由于饮食中磨料的不确定性和潜在的混淆作用，在功能上的共识很少。为了解决这一难题，本研究收集了灵长类动物饮食中硅质成分的系统数据，并揭示了野生活体灵长类动物饮食中硅质成分、牙齿形态特征和咀嚼性能之间的关系。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。

The consumption of tough, abrasive foods may have contributed to key changes in the teeth of our earliest human ancestors. Researchers have proposed that the ingestion of particles that are abrasive to tooth enamel was an important force structuring dental traits during human evolution, including thicker enamel and larger tooth size. A debate exists regarding the type of abrasive material that would have been the most important for understanding the evolution of human teeth. This doctoral dissertation research project investigates whether tooth size and enamel thickness vary with the 1) ingestion of abrasive particles, and (2) how well primates chew their food in the wild. This project trains students from backgrounds underrepresented in STEM in field and lab methods, some leading to independent honors projects, and contributes K-12 and museum educational outreach. The project further contributes to capacity building at a long-term primate field station in a UNESCO World Heritage Site.The long-term objective of this research is to inform hypotheses that pivot around form-functional relationships between primate foraging behaviors and dental traits, an essential task for inferring behavior in the human fossil record. The investigators (i) differentiate and quantify phytoliths and grit in the diets of the monkeys and compare this variation to (ii) variation in fecal particulate size (a metric of chewing performance); and (iii) variation in tooth size and enamel thickness collected from population-specific skeletal collections. This project leverages established and emerging techniques in primate dental ecology to unravel a long-standing puzzle. Molar size and enamel thickness are traits of enduring importance to paleoanthropologists, being central to phylogenetic reconstructions and dietary inference, but with little functional consensus due to the uncertain and potentially confounding effects of abrasive material in the diet. To resolve this puzzle, this investigation collects systematic data on the siliceous composition of primate diets and uncovers the relationships between this composition, dental morphological traits, and chewing performance in living primates in the wild.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.