Collaborative Research: Experimental assessment of dental microwear formation

人们普遍认为，古人类的进化受到饮食的强烈影响，然而，关于古人类究竟吃了哪些食物的争论仍在继续。特别是，目前还不清楚这些早期人类的巨大的颌和巨大的牙齿是否进化到可以加工坚果和种子等坚硬的食物，或者坚硬的纤维食物，可能包括草。这场争论的一个重要证据来自食物对牙齿造成的微观损害，以及可能附着在食物上的沙砾颗粒。这项研究进行的实验旨在评估如何解释这种微观损害的模式，以便重建化石人类的饮食。这项研究将具有广泛的意义，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，这反过来可能影响我们对古代环境及其随时间变化的理解；3)为解释史前和历史人类种群的摄食行为提供实验基础。该项目还支持不同职业阶段的pi研究，包括一名早期职业女性研究员，以及研究生、本科生和高中生志愿者（与范德比尔特科学与数学学院等当地大学和社区项目合作）。所有学生都将获得科学研究成果的执行和交流（高中生也将在青年科学家期刊上发表），专业发展技能，以及提高他们作为未来专业人员实施研究，教育和推广活动的能力和愿望的指导。实验将使用液体和氧气模型来评估不同韧性和硬度的食物对牙齿表面的影响，以及沙子、种子壳碎片和其他非常坚硬的植物部分等磨料颗粒的硬度和大小。对牙齿造成的微观损伤将使用表面扫描和纳米机械力显微镜进行评估，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，这将使我们能够评估人类牙齿化石中看到的损伤模式的原因，从而使我们能够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，以确定是否可以根据个人磨损痕迹的特征开发出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.