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

本项目旨在研究灵长类动物的饮食与咀嚼行为之间的关系，以加深我们对灵长类动物和人类进食行为的进化和变异的理解。研究人员将测量23种灵长类动物的咀嚼模式，这些物种被给予一系列物质特性的食物，以了解每个物种的个体如何处理不同的食物，以及这种处理与他们的下巴和头骨的形状有何关系。这些比较数据不仅对构建现存灵长类物种的生态学研究具有重要意义，而且对于根据颌骨和头骨化石重建灭绝的灵长类和古人类物种的饮食和摄食行为也是重要的。该项目将促进采用跨学科的方法进行培训和教育，并将支持对一名博士后研究员、研究生和本科生以及当地STEM教师和学生的培训和指导，所有这些人都将参加实验室学徒、科学报告和面向当地机构和普通公众的公共宣传。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发展一种新的训练环境。灵长类头骨的表型变异受到咀嚼压力的影响，分类群依赖于具有专门的颌骨、牙齿和颌部肌肉的坚硬或坚硬的食物。然而，在现存的灵长类动物和化石灵长类动物中，饮食和颌骨形态之间的联系却知之甚少。难以理解喂养装置中的适应性多样性是由于与饮食相关的咀嚼和负荷行为的证据的两个缺陷。第一个事实是，罕见的、高强度的力在骨骼中引发的生理和进化反应与低强度的周期性载荷相同。在头骨中，第二个相关的问题是，对食物特性对咀嚼行为变化的作用的了解令人惊讶地不完整，而咀嚼行为的变化是灵长类下巴形态与负荷相关的变化的基础。考虑到在化石人类中，周期性负荷被用来解释下颌的粗壮程度是无处不在的，关于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。利用国内机构保存的23个典型灵长类物种的活体数据，本项目检验了食物材料特性影响灵长类颌骨周期性负荷变化的咀嚼参数的假说：咀嚼频率、咀嚼投资和咀嚼持续时间。高速视频将记录隔离和不受限制的成年灵长类动物与饮食相关的动态咀嚼模式，展示了一组已知的五种食物，这些食物涵盖了一系列物质特性，与野生灵长类动物摄取的物品的价值多样性平行。种内和种间分析将比较咀嚼参数与食物硬度、韧性和各自的口腔碎裂指数。由于其实验和比较的重点，这种活体研究可能会为生物人类学和其他有机学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.