Collaborative Research: Experimental assessment of dental microwear formation

人们普遍认为，人类的进化受到饮食的强烈影响，但关于他们到底吃哪种食物的争论仍然存在。 特别是，目前还不清楚这些早期人类的巨大颌骨和巨大牙齿是否进化为处理坚果和种子等坚硬食物，或者可能包括草在内的坚韧纤维食物。 这场争论中的一个重要证据来自食物对牙齿造成的微观损伤，以及可能粘附在食物上的砂砾颗粒。 这项研究进行了旨在评估如何解释这种微观损伤模式的实验，以重建化石人类的饮食。 这项研究将产生广泛的影响，包括1）提高我们对人类进化原因的理解，2）评估已建立的方法，并开发新的方法，重建灭绝动物的饮食，这反过来可能会影响我们对古代环境的理解，以及它们如何随着时间的推移而变化，3）为解释史前和历史人类种群的进食行为提供实验基础。 该项目还支持在不同职业阶段的PI研究，包括职业生涯早期的女性研究员，以及研究生，本科生和志愿者高中生（与当地大学和社区项目合作，如范德比尔特科学和数学学校）。所有学生将在执行和交流科学研究成果方面接受指导（高中生也将发表在青年科学家杂志上），专业发展技能，以及提高他们作为未来专业人士实施研究，教育和推广活动的能力和愿望。实验将使用suid和奥维德模型来评估食物的不同韧性和硬度对牙齿表面的影响，以及研磨颗粒如沙子、种子壳碎片和其它非常硬的植物部分的硬度和尺寸。 将使用表面扫描和纳米机械力显微镜评估对牙齿造成的微观损伤，并使用统计方法来确定食物、颗粒或它们之间的相互作用是否会导致损伤模式。反过来，这将有助于评估化石人类牙齿中所见损伤模式的原因，从而更精确地评估早期人类的饮食。 然后将在纳米尺度上评估牙齿上的损伤，以确定是否可以基于对个体磨损痕迹的表征开发一种新的饮食重建方法。

It is widely understood that the evolution of hominins was strongly influenced by diet, and yet there continues to be a debate about precisely which types of foods were eaten by them. In particular, it is unclear whether the massive jaws and huge teeth of these early humans evolved to process hard foods like nuts and seeds, or tough, fibrous foods that might have included grasses. An important piece of evidence in this debate comes from the microscopic damage done to teeth by food, and particles of grit that may adhere to food. This study conducts experiments designed to evaluate how patterns of such microscopic damage should be interpreted in order to reconstruct diet in fossil humans. This study will have broad implications, including 1) improving our understanding of why humans evolved, 2) evaluating established methods, and developing new methods, of reconstructing diet in extinct animals, which in turn may influence our understanding of ancient environments and how they changed over time, and 3) providing an experimental basis for interpreting feeding behavior in both prehistoric and historic human populations. The project also supports the research of PIs at diverse career stages, including an early-career female researcher, as well as graduate, undergraduate, and volunteer high school students (in collaboration with local university and community programs like the Vanderbilt School for Science and Math). All students will receive mentoring in performing and communicating results of scientific research (high school students will also publish in the Young Scientist journal), professional development skills, and improving their ability and desire to implement research, education and outreach activities as future professionals.Experiments will use suid and ovid models to evaluate the effect on tooth surfaces of varying toughness and hardness of foods, as well as the hardness and size of abrasive particles like sand, seed shell fragments and other very hard plant parts. The microscopic damage done to teeth will be assessed using surface scans and nanomechanical force microscopy, and statistical methods will be used to determine whether foods, particles, or an interaction between them drives patterns of damage. This, in turn, will allow an evaluation of the causes of damage patterns seen in the teeth of fossil humans, which will in turn allow a more precise assessment of the diets of early humans. The damage on the teeth will then be assessed on a nano-scale in order to determine if a new method of dietary reconstruction can be developed based on a characterization of individuals wear marks.