Doctoral Dissertation Research: Understanding enamel hypoplasia in great apes of known life history

就像树木的年轮提供了与过去环境条件有关的生长模式的记录一样，牙齿可以保存牙齿发育过程中所经历的生理压力的记录。这个博士论文项目将使用新的成像和分析方法来研究维龙加山地大猩猩与压力相关的牙齿缺陷，这些大猩猩的长期行为、健康和气候数据是可用的。将特定的牙齿缺陷与特定的生活事件联系起来的能力将提高我们对现存类人猿和古人类化石中生态、社会和生理压力因素之间复杂相互作用的理解。该项目将支持STEM领域的学生指导和培训，以及研究现场的合作和保护工作。牙齿对健康和发育的研究很重要，因为它们提供了一个永久和详细的记录，绝对按时间顺序生长。当生长受到营养不良和疾病等压力因素的干扰时，牙釉质发育不良表现为牙齿表面的凹槽。发育不全缺陷通常是通过低倍率的牙釉质表面观察来评分的，在类人猿中，正常和异常形态之间的界限从未被定量定义过。这个项目使用定量的标准来诊断缺陷，并建立一个最小的阈值来确定什么是缺陷，什么是在正常变化的范围内。目的包括：(1)定量确定缺陷的存在，并测试山地大猩猩和其他类人猿之间缺陷患病率和形态的差异；(2)分析类人猿冠生长的显微解剖学参数，确定影响类人猿冠缺陷形态变化的因素；(3)检测缺陷时间与山地大猩猩个体外伤、疾病、群体间相互作用等应激事件的对应关系，首次获得野生大猩猩釉质发育不全的病因学数据。通过评估缺陷形态、牙釉质生长的微观解剖参数和相关生活史记录中记录的压力因素之间的关系，本研究将加深我们对类人猿缺陷表达差异的理解，从而提高我们在古人类背景下更自信地解释牙釉质缺陷的能力。

Much like tree rings provide a record of growth patterns related to past environmental conditions, teeth can preserve a record of physiological stress experienced during dental development. This doctoral dissertation project will use novel imaging and analytical methods to study stress-related dental defects in Virunga mountain gorillas for whom long-term behavioral, health, and climate data are available. The ability to link specific dental defects to specific life events will improve our understanding of the complex interplay among ecological, social, and physiological stressors in both extant great apes and fossil hominins. The project will support student mentoring and training in STEM fields as well as collaborations and conservation efforts at the research site. Teeth are important to studies of health and development because they provide a permanent and detailed record of their absolute chronological growth. Enamel hypoplasias manifest as grooves on the tooth surface when growth is disrupted by stressors such as undernutrition and disease. Hypoplastic defects are usually scored by low-power enamel surface observation, and the boundary between normal and abnormal morphology has never been quantitatively defined in great apes. This project employs quantitative criteria to diagnose defects, and establishes a minimum threshold for determining what is a defect versus what is within the bounds of normal variation. Aims include: (1) determining defect presence quantitatively, and testing for differences in defect prevalence and morphology among mountain gorillas and other great apes; (2) analyzing microanatomical parameters of crown growth to determine which factors influence variation in defect morphology among great apes; and (3) testing correspondence between defect timing and stressful events (e.g. injury, disease, intergroup interactions) in the recorded history of individual mountain gorillas to produce the first data on enamel hypoplasia etiology in wild gorillas. By assessing the relationships between defect morphology, microanatomical parameters of enamel growth, and documented stressors in associated life history records, the proposed research will deepen our understanding of factors that underlie differences in defect expression among great apes, and thus improve our ability to more confidently interpret enamel defects in paleoanthropological contexts.