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

面颊牙齿的形状多种多样，大致反映了现存灵长类及其化石近亲食用的食物。然而，牙齿不同于其他生物结构，因为它们没有能力重塑或修复自己，而是必须继续执行它们的咀嚼功能，即使它们磨损了。这一问题在灵长类等长寿动物身上加剧。这个项目调查了牙齿磨损如何影响两个具有高度反差牙齿的灵长类分类群体-类人猿和东半球猴子-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对博物馆标本的MicroCT扫描来收集，并通过向研究人员、教育工作者和普通公众开放的基于网络的储存库进行访问，从而改善获取机会和教育机会，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、免费提供的软件来加强现有方法，并通过专门讨论这一主题的会议促进科学交流。本科生将接受适用于各种STEM专业的科学过程和方法方面的培训。项目成果将通过一个展览公开交流，让普通观众与杜克狐猴中心的研究人员和灵长类化石标本直接互动，并为他们的青少年暑期科学夏令营开发教育材料。这个项目解决了在科学理解面颊牙齿形状如何随着牙齿磨损而变化以及随之而来的功能影响方面的重大差距。尽管人们普遍承认，自然选择在灵长类牙齿的整个生殖生命中继续发挥作用，即使牙齿磨损，但大多数灵长类摄食生态学研究都集中在牙齿最初的原始形态上。这一重点是由于方法依赖于使用牙冠的可识别和同源特征，这些特征往往因磨损而高度修改或消失，使磨损的牙齿缺乏信息。咬合表面几何形状的无同源量化的发展，称为牙齿地形图计量学，解放了研究人员扩展跨磨损系列的比较，并更好地表征终身牙齿形态-功能关联。这项研究利用这些技术来解决猿和东半球猴子(所谓的双齿猴)磨牙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特征。具有不同饮食和摄食底物偏好的活物种将被用于包含牙齿地形、牙釉质厚度分布和牙齿磨损的系统发育比较。这一广泛的比较样本将成为研究3500万年前至1500万年前采样充分的类人猿化石中牙齿磨损的基础，以了解化石类群的饮食生态，并评估与仍在活着的类人猿中观察到的原始尖牙模式相比，猴子双齿臼齿的适应意义。这项工作的结果将描述双齿猴牙齿的终生功能有效性，并提供在过去1500万年中观察到的旧大陆猴子辐射相对于类人猿辐射的成功情况。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.