The mechanics of anterior tooth use in primates

树木分泌物喂养的普遍性（例如，树胶和树液）或食胶性，表明这种进食行为对灵长类动物的进化有着重大影响。 一些食胶灵长类动物物种积极引发树木分泌物流机械破坏树木与他们的前牙。 这种类型的咬行为被定义为刨削。 这个项目将记录在南美普通绒猴（Callithrix jacchus）凿槽过程中的颌骨力和颌骨张开（或颌骨张开的幅度）。 人类学家以前曾假设，树木刨削涉及大的颌骨力量或大颌骨间隙相对于那些在咀嚼和切口的经验。 提出这些假设时，并没有试图测量凿削过程中的颌力或颌间隙。 这项研究将产生新的信息，说明食胶动物可能对灵长类动物头骨的形状和功能产生的机械影响。 根据初步数据，刨削似乎需要相对较大的钳口间隙，但不一定需要相对较大的钳口力。 这一发现与早期关于这种行为的观点相矛盾，并强调了灵长类动物咬人时下颚张开的重要性。 除了少数例外，灵长类动物下颌和牙齿功能的体内研究（即，对活体动物进行行为的研究）并没有集中在前牙的使用或咬。 尽管一些研究人员注意到叮咬对灵长类动物的形态和生态可能具有重要意义，但这一缺点仍然存在。 这个提议很重要，因为它将是灵长类动物咬行为期间颌骨力学的第一个体内研究之一，因此将为咬如何影响灵长类动物头骨的形式和功能提供新的见解。 在这个项目中收集的体内数据将发挥关键作用，在研究适应刨绒猴头部。 利用最近收集的野外数据，实验室中绒猴挖掘的基质将被制成模仿绒猴在野外挖掘的树木。 通过将实验室基质与野生基质相匹配，该项目可以更真实地研究凿削过程中的颌骨性能。 这反过来又为这种行为的适应性假设提供了改进的测试。 此外，在体内的数据是一个核心的参考比较的头骨功能形态，数量遗传学的头骨形状，颌骨肌肉纤维结构和颌骨骨小梁结构之间的绒猴和非凿绢毛猴。 这些分析将提供一个广泛的特征树刨适应绒猴，并作为一个模型的方法，为其他人类学家结合实验室，现场和头骨形态测量方法在研究灵长类动物的适应。 该项目的另一个重要目标是通过整合教育和研究来培养学生。 本项目将强调通过积极参与促进学生学习和培训。 由于活体研究技能只能通过互动学徒制来掌握，而这些机会相对较少，因此该项目将为生物人类学提供重要的教育资源。 最后，研究绒猴头骨功能和树木刨挖生态学的包容性项目将美国和巴西大学的研究人员联系起来，促进他们之间的互动和知识交流。

The prevalence of tree exudate feeding (e.g., tree gums and saps) or gummivory among primates suggests that this feeding behavior has significantly influenced primate evolution. Some gummivorous primate species actively elicit tree exudate flow by mechanically damaging trees with their anterior teeth. This type of biting behavior is defined as gouging. This project will record jaw forces and jaw gapes (or the magnitude of jaw opening) during gouging in the South American common marmoset (Callithrix jacchus). Anthropologists previously have hypothesized that tree gouging involves large jaw forces or large jaw gapes relative to those experienced during chewing and incision. These hypotheses have been put forth without any attempt to measure the jaw forces or jaw gapes during gouging. The proposed research will generate novel information about the possible mechanical effects that gummivory might have on primate skull form and function. Based on preliminary data, gouging appears to require relatively large jaw gapes, but not necessarily relatively large jaw forces. This finding contradicts earlier ideas about this behavior and emphasizes the under-appreciated significance of jaw gapes in primate biting. With few exceptions, in vivo studies of primate jaw and tooth function (i.e., studies of living animals performing a behavior) have not focused on anterior tooth use or biting. This shortcoming persists despite several researchers noting the likely significance of biting for primate morphology and ecology. This proposal is important because it will be one of the first in vivo studies of jaw mechanics during a biting behavior in primates and therefore will contribute new insights into how biting might affect the form and function of primate skulls. The in vivo data collected in this project will play a key role in studying adaptations for gouging in the marmoset head. Using recently collected field data, the substrates that marmosets gouge in the lab will be made to mimic the trees that marmosets gouge in the wild. By matching the lab substrates to wild ones, this project can more realistically study jaw performance during gouging. This in turn provides improved tests of adaptive hypotheses for this behavior. Furthermore, the in vivo data are a core reference for comparisons of skull functional morphology, quantitative genetics of skull form, jaw-muscle fiber architecture and jaw trabecular structure between marmosets and non-gouging tamarins. These analyses will provide an extensive characterization of tree gouging adaptations in marmosets and serve as a model approach for other anthropologists for combining lab, field and skull morphometric methods in studying primate adaptations. Another important goal of this project involves training students through integrating education and research. The promotion of student learning and training through active participation will be emphasized in this project. Because in vivo research skills can only be mastered through interactive apprenticeship and these opportunities are relatively rare, this project will provide a significant educational resource for biological anthropology. Finally, the inclusive project studying skull function and ecology of tree gouging in marmosets links researchers from U.S. and Brasilian universities fostering interaction and intellectual exchange between them.