Doctoral Dissertation Improvement: Challenging Assumptions of Dental Senescence Using a Primate Framework

广泛的牙齿​​磨损可能会消融牙齿的功能特征，导致牙列有效分解食物的能力丧失（即牙齿衰老）。据推测，这种功能丧失会阻碍获取食物，导致健康状况、繁殖成功率和生存能力下降。然而，牙齿如何以及在什么时候达到衰老状态尚不清楚，牙齿衰老对个人健康、营养和行为的影响程度也不清楚。自然选择应该产生即使磨损也能保持破碎食物的能力的牙齿，并且只有在严重磨损时才会停止工作。个体可以通过行为机制补偿牙齿损伤，或者可以通过性别和/或社会等级等个人特征来缓冲磨损的影响。 这项研究由博士生 James Millette（科罗拉多大学）在 Michelle Sauther 博士的指导下进行，将基于地理信息系统的牙齿形态牙齿形态分析与个体行为生态学、健康和营养数据相结合，以检查环尾狐猴 (Lemur catta) 磨损牙齿形态、食物加工能力和行为之间的关系马达加斯加贝扎马哈法利特别保护区。该人群因食用罗望子水果而表现出不同程度的牙齿磨损和频繁的牙齿脱落。该研究将：1）确定何种程度的牙齿磨损与健康和营养状况下降相关；2）评估行为机制是否可以缓冲个体免受牙齿磨损的影响；3）检查等级和性别等个人特征是否可能影响这种模式。它还将为改进牙齿地形分析的使用提供有价值的背景信息，以评估磨损的牙齿功能及其与灵长类化石记录中的行为和营养的关系。 这项研究的开展将通过加强国际研究合作、对马达加斯加学生的培训和对当地社区的教育推广以及加强对濒危栖息地的保护来补充。

Extensive tooth wear may ablate functional features of the teeth, resulting in the end of the dentition's capacity to effectively break down food items (i.e., dental senescence). Such a loss of function is presumed to impede access to foods, resulting in reduced health status, reproductive success, and ability to survive. Nevertheless, how and at what point of wear teeth reach a senescent state is not yet well understood, nor is the extent to which dental senescence may affect individual health, nutrition and behavior. Natural selection should produce teeth which maintain the ability to fracture foods despite wear, and which only cease to function with severe wear. Individuals may compensate for dental impairment through behavioral mechanisms, or may be buffered against the impacts of wear by individual traits such as sex and/or social rank.This study, by doctoral student James Millette (University of Colorado), under supervision of Dr. Michelle Sauther, combines Geographic Information Systems-based dental topographic analysis of tooth form with individual behavioral-ecology, health and nutritional data to examine relationships between worn tooth morphology, food processing ability and behavior for ring-tailed lemurs (Lemur catta) of the Beza Mahafaly Special Reserve, Madagascar. This population demonstrates well-documented, varying levels of tooth wear and frequent tooth loss due to tamarind fruit consumption.The research will: 1) determine what level of dental wear is associated with reduced health and nutrition, 2) assess if behavioral mechanisms can buffer individuals against the effects of dental wear, and 3) examine whether individual traits such as rank and sex may impact such patterns. It also will provide valuable contextual information towards improved use of dental topographic analysis for assessing worn tooth functionality and its relation to behavior and nutrition within the primate fossil record. The conduct of the research will be complemented by enhancing international research collaborations, training of Malagasy students and educational outreach to local communities, and enhanced conservation of endangered habitats.