Collaborative Research: Tooth Wear and Diet Among Living and Fossil Primates

不同形状的颊齿广泛地反映了现存灵长类动物及其化石亲属的饮食习惯。然而，牙齿与其他生物结构的区别在于，它们没有重塑或修复自己的能力，而是必须继续执行其咀嚼功能，即使它们磨损了。这是一个在灵长类等长寿动物中加剧的问题。本项目研究牙齿磨损如何影响两个具有高度对比牙齿的灵长类动物分类组-猿和旧大陆猴子-的食物分解功能，并探索这些模式揭示了它们之间的饮食进化和竞争。这项工作的数据将通过博物馆标本的microCT扫描收集，并通过一个面向研究人员、教育工作者和公众开放的网络存储库提供，以提高访问和教育机会，特别是在检查稀有化石方面。这项研究将通过为科学界开发新的免费软件来加强现有的方法，并通过专门讨论这一主题的会议来促进科学交流。本科生将接受适用于各种STEM专业的科学过程和方法的培训。项目的研究结果将通过一个展览公开传播，让普通观众直接与杜克狐猴中心的研究人员和灵长类化石标本互动，并通过为他们的青少年暑期科学夏令营开发教育材料。这个项目解决了在牙齿磨损时颊齿形状如何变化以及随之而来的功能影响的科学理解方面的重大差距。尽管普遍承认，自然选择继续在灵长类动物的牙齿在其整个生殖生命，即使牙齿磨损，大多数灵长类动物的摄食生态学研究集中在最初的原始形式的牙齿。这一重点已经出现的方法依赖于使用牙冠的可识别和同源的功能，这往往是高度修改或磨损消失，使磨损的牙齿没有信息。无同源性的咬合面几何形状的量化，被称为牙齿地形测量的发展，解放了研究人员，以扩大跨磨损系列的比较，并更好地表征寿命牙齿形状功能协会。这项研究利用这些技术来解决猿和旧大陆猴（所谓的bilophodont）臼齿的不同结构模式如何随着牙齿磨损而变化，以保持和/或增强与咀嚼效率和耐磨性相关的功能。具有不同饮食和摄食基质偏好的活体物种将用于结合牙齿形貌、釉质厚度分布和牙齿磨损的遗传学信息比较。这一广泛的比较样本将成为研究3500万至1500万年前采样良好的化石类人猿牙齿磨损的基础，以了解化石分类群的饮食生态学，并评估猴子的双齿臼齿与现存猿类中仍然观察到的原始尖齿模式相比的适应意义。这项工作的结果将描述双齿牙的寿命功能有效性，并告知观察到的旧世界猴辐射的成功相比，在过去的1500万年猿。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

The diverse shapes of cheek teeth are broadly reflective of the diets that living primates and their fossil relatives consumed. Yet teeth stand apart from other biological structures in that they do not have the capacity to remodel or repair themselves and instead must continue to perform their chewing function, even as they wear down. This is an issue exacerbated in long-lived animals such as primates. This project investigates how tooth wear affects food break-down functionality in two primate taxonomic groups with highly contrasting teeth—apes and Old World monkeys—and explores what these patterns reveal about the dietary evolution and competition between them. Data for this work will be collected via microCT scanning of museum specimens and made accessible via a web-based repository open to researchers, educators, and the general public, improving access and educational opportunity, particularly for examining rare fossils. This research will enhance existing methodologies through development of new, freely available software for the scientific community and promote scientific communication with a conference session dedicated to this subject matter. Undergraduates will receive training in the scientific process and methods applicable to a wide range of STEM professions. Project findings will be publicly communicated through an exhibit that allows general audiences direct interaction with researchers and fossil primate specimens at the Duke Lemur Center, and through development of educational material for their youth summer science camps.This project addresses the significant gap in scientific understanding of how cheek tooth shape changes as teeth wear and the attendant functional implications. Despite general acknowledgement that natural selection continues to operate on primate dentitions throughout their reproductive lives, even as teeth wear, the majority of primate feeding ecology investigations have focused on the initial pristine form of teeth. This focus has emerged from the methodological dependence on using identifiable and homologous features of tooth crowns, which are often highly modified or obliterated by wear, rendering worn teeth uninformative. The development of homology-free quantifications of occlusal surface geometry, known as dental topographic metrics, liberates researchers to extend comparisons across wear series and better characterize lifetime dental form-function associations. This research leverages these techniques to address how the divergent structural patterns of ape and Old World monkey (so called bilophodont) molars change with tooth wear to maintain and/or enhance features related to chewing efficiency and wear resistance. Living species with diverse dietary and feeding substrate preferences will be used in phylogenetically-informed comparisons incorporating dental topography, enamel thickness distribution, and tooth wear. This broad comparative sample will form the basis for the study of dental wear among well-sampled fossil anthropoids from 35 to 15 million years ago to inform both the dietary ecology of fossil taxa and evaluate the adaptive significance of bilophodont molars of monkeys compared to the primitive cusp pattern still observed in living apes. The results of this work will describe the lifetime functional effectiveness of bilophodont teeth and inform the observed success of the Old World monkey radiation compared to that of apes over the past 15 million years.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.