Dietary Properties and Chewing Patterns in Primates: An Analysis of Cyclical Loading

本项目研究灵长类动物饮食与咀嚼行为之间的关系，以提高我们对灵长类动物和人类摄食行为的进化和变化的理解。研究人员将测量23种灵长类动物的咀嚼模式，这些灵长类动物被给予一系列材料性质的食物，以观察每个物种的个体如何处理不同的食物，以及这种处理与它们的下巴和头骨形状之间的关系。这些比较数据不仅对构建现存灵长类物种的生态研究具有重要意义，而且对基于颌骨和头骨化石重建已灭绝灵长类动物和人类物种的饮食和摄食行为具有重要意义。该项目将促进涉及代表性不足群体成员的跨学科培训和教育方法，并将支持对博士后、研究生和本科生以及当地STEM教师和学生的培训和指导，他们都将参与实验室学徒、科学演讲和向当地机构和公众进行公众宣传。因此，对社会的另一个好处包括为下一代学术研究人员和教育工作者提供一个新的培训环境。灵长类动物颅骨的表型变异受到咀嚼压力的影响，依赖坚硬食物的类群有专门的颚、牙齿和颚肌肉。然而，在现存和化石灵长目动物中，饮食和颌形之间的联系尚不清楚。由于缺乏与饮食有关的咀嚼和加载行为的证据，因此难以理解进食装置的适应性多样性。第一个事实是，不频繁的、高强度的力在骨骼中引起的生理和进化反应与低强度的、周期性的负荷相同。在头骨中，第二个与之相关的问题是，我们对食物特性在咀嚼行为变化中所起的作用的认识令人惊讶地不完整，而咀嚼行为是灵长类动物颌骨形式中负荷相关变化的基础。考虑到在古人类化石中，人们普遍使用周期性载荷来解释颌骨的健壮性，这种咀嚼模式的关键行为数据的显著缺乏怎么强调都不为过。本项目利用23种代表性灵长类动物的体内数据，验证了食物材料特性影响灵长类动物颌骨循环负荷变化的咀嚼参数的假设：咀嚼频率、咀嚼投入和咀嚼持续时间。高速视频将记录与饮食相关的动态咀嚼模式，在被隔离和不受约束的成年灵长类动物中呈现已知的五种食物，这些食物跨越了一系列的物质特性，与野生灵长类动物摄入的食物的价值多样性相当。种内和种间分析将比较咀嚼参数与食物硬度、韧性和各自的口腔破碎指数。由于其实验和比较的重点，这种体内研究可能会为生物人类学和其他有机体和生物医学领域的理论和方法进步提供信息。

This project investigates relationships between diet and chewing behaviors in primates, to improve our understanding of the evolution and variation in primate and hominin feeding behaviors. The investigators will measure chewing patterns in 23 primate species that are given foods spanning a range of material properties, to see how individuals in each species process the different foods and how this processing relates to the shape of their jaw and skull. These comparative data will be important not only for framing ecological research in living primate species, but for reconstructing diet and feeding behaviors in extinct primate and hominin species based on fossil jaws and skulls. The project will foster interdisciplinary approaches to training and education involving members of under-represented groups, and will support training and mentorship of a postdoctoral fellow, graduate students and undergraduates as well as local STEM teachers and students, all of whom will participate in lab apprenticeship, scientific presentations and public outreach to local institutions and the lay public. Therefore, another benefit to society includes development of a novel training environment for the next generation of academic researchers and educators.Phenotypic variation in the primate skull is influenced by masticatory stress, with taxa relying on stiff or tough foods having specialized jaws, teeth and jaw muscles. However, the link between diet and jaw form in living and fossil primates is poorly understood. Difficulty understanding adaptive diversity in the feeding apparatus is due to two shortcomings of the evidence about diet-related chewing and loading behaviors. The first is the fact that infrequent, high-magnitude forces elicit the same physiological and evolutionary responses in bone as do low-magnitude, cyclical loads. In the skull, a second and related issue is a surprisingly incomplete knowledge of the role of food properties on variation in chewing behaviors that underlie load-related variation in primate jaw form. Given the ubiquity with which cyclical loading is invoked to explain jaw robusticity in fossil hominins, the remarkable lack of key behavioral data on this chewing pattern cannot be overstated. Using in vivo data on 23 representative primate species kept in domestic institutions, this project tests the hypothesis that food material properties affect masticatory parameters underlying variation in cyclical loading of primate jaws: chewing frequency, chewing investment, and chewing duration. High-speed video will record dynamic diet-related chewing patterns in isolated and unrestrained adult primates presented a known mass of five foods that span a range of material properties paralleling the diversity of values for items ingested by wild primates. Intra- and interspecific analyses will compare chewing parameters with food stiffness, toughness, and respective oral fragmentation indices. Due to its experimental and comparative focus, this in vivo research is likely to inform theoretical and methodological advances in biological anthropology and other organismal and biomedical fields.