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

食用坚硬、研磨的食物可能是导致我们最早的人类祖先牙齿发生关键变化的原因之一。研究人员提出，在人类进化过程中，对牙釉质具有研磨性的颗粒的摄取是形成牙齿特征的重要力量，包括更厚的釉质和更大的牙齿尺寸。关于哪种研磨材料对于理解人类牙齿的进化是最重要的，存在着争论。这项博士论文研究项目调查牙齿大小和牙釉质厚度是否会随着1)磨料颗粒的摄入而变化，以及(2)灵长类动物在野外咀嚼食物的情况。该项目对STEM中代表性不足的学生进行实地和实验室方法的培训，其中一些导致了独立的荣誉项目，并有助于K-12和博物馆的教育推广。该项目还有助于联合国教科文组织世界遗产地长期灵长类野外站的能力建设。这项研究的长期目标是提出假设，围绕灵长类觅食行为和牙齿特征之间的形式-功能关系，这是在人类化石记录中推断行为的基本任务。研究人员(I)区分和量化猴子饮食中的植硅石和砂砾，并将这种变化与(Ii)粪便颗粒大小(咀嚼性能的指标)的变化进行比较；(Iii)从特定种群的骨骼采集中收集的牙齿大小和牙釉质厚度的变化。这个项目利用灵长类牙齿生态学中已有的和新兴的技术来解开一个长期存在的谜团。磨牙大小和釉质厚度对古人类学家来说具有持久的重要性，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和潜在的混杂影响，功能上的共识很少。为了解决这个问题，这项调查收集了关于灵长类食物硅质成分的系统数据，并揭示了这种组成、牙齿形态特征和野外生存灵长类动物咀嚼性能之间的关系。这一奖项反映了NSF的法定使命，并通过使用基金会的智力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.