Doctoral Dissertation Improvement: Plio-Pleistocene Hominin Teeth from Dmanisi, Georgia

第一个离开非洲家园的人类物种的身份和这一事件的时间仍然存在很大争议。问题在于，很少有关键年代的遗址既能发现重要的人类遗骸，又能从地质背景中找到可以可靠确定年代的人工制品。位于格鲁吉亚共和国的德马尼西遗址，对中国和爪哇其他可能的早期遗址提出了质疑，并增加了我们对第一批人类从非洲扩散的理解。德马尼西的历史可以追溯到最早的更新世（177万年），是一个拥有丰富古生物学和考古学证据的遗址，它在世界任何地方都从一个单一的层面上产生了最大的早期人属遗骸样本。此外，这些化石在形态和时间上都处于最早的直立人和后来的直立人之间的中间位置。许多研究表明，牙冠和牙根大小的信息，连同观察的形态特征，可以显着有助于上新世更新世人类的分类，系统发育和功能分析。这项研究的重点是从Dmanisi遗址不断增长的人类牙齿样本。德马尼西的牙齿样本现在包括来自三个下颌骨的牙齿，两个头盖骨，以及一些孤立的发现，它们共同代表了至少3个人。许多标本目前尚未发表。所有这些都将通过描述和测量记录下来，并辅之以数码摄影和X射线摄影等成像技术。然后将分析变异模式，以确定牙齿之间的度量和形态差异是否可能反映种间或种内变异，包括性别之间的差异。德马尼西的牙齿遗骸将与其他来自东非和东南亚的早期直立人（=ergaster）牙齿进行比较，并与来自图尔卡纳盆地和奥杜瓦伊峡谷的早期人属标本进行比较。这项分析将记录能人和早期直立人的牙齿变异范围，确定德马尼西标本在该范围内的位置，并帮助确定德马尼西样本和其他人类群体之间任何可能的系统发育（祖先-后代）关系。 这种齿系的定量研究将有助于更好地理解人类种群内和种群间的变异以及人属最早成员的分类。这项研究还将提供一个独特的数据集，用于评估有关原始人从非洲家园的最初迁移和最早的欧亚人的古生物学的情况。项目资助的更广泛影响是，它将允许Co-PI前往格鲁吉亚分析牙科材料，并允许与格鲁吉亚和美国科学家合作。拟议的研究还为Co-PI和参与该项目的其他人提供了实验室数据收集和分析方面的出色教育机会。

The identity of the first human species to disperse out of the African homeland and the timing of this event remain highly controversial. The problem lies in the fact that few sites of critical age have yielded both significant hominin remains and artifacts from geologic contexts which can be reliably dated. The Dmanisi site in the Republic of Georgia challenges the doubts raised in respect to other, potentially early sites in China and Java, and adds to our understanding of the first hominin dispersals from Africa. Dmanisi, which dates to the earliest Pleistocene (1.77 mya), is a site rich in paleontological and archaeological evidence, and it has produced the largest sample of early Homo remains from a single level at a locality anywhere in the world. In addition, the fossils occupy an intermediate position, both morphologically and temporally, between earliest Homo and later Homo erectus. Many studies have demonstrated that information about tooth crown and root size together with observations of morphological traits can contribute significantly to taxonomic, phylogenetic, and functional analyses of Plio-Pleistocene hominins. This study focuses on the continually growing hominin dental sample from the site of Dmanisi. The Dmanisi dental sample now includes teeth from three mandibles, two crania, and a number of isolated finds, which together represent a minimum of 3 individuals. Many of the specimens are currently unpublished. All will be documented through description and measurement, aided by imaging techniques such as digital photography and radiography. Patterns of variation will then be analyzed to determine if the metric and morphologic differences among the teeth likely reflect interspecific or intraspecific variation, including differences between the sexes. The Dmanisi dental remains will be compared with other early Homo erectus (=ergaster) teeth from East Africa and Southeast Asia, and to specimens of earlier Homo from the Turkana basin and Olduvai Gorge. This analysis will document the range of dental variation for Homo habilis and early Homo erectus, establish the position of the Dmanisi specimens within that range, and help to identify any probable phylogenetic (ancestor-descendant) relationships between the Dmanisi sample and the other hominin groups. This quantitative work on dentition will contribute to a better understanding of intra- and inter-populational hominin variation and the taxonomy of the earliest members of the genus Homo. This research will also provide a unique dataset with which to evaluate scenarios concerning the initial migration of hominins from the African homeland and the paleobiology of the earliest Eurasians. The broader impact of project funding is that it will permit the Co-PI to travel to Georgia for analysis of the dental material and allow for collaboration with both Georgian and US scientists. The proposed research also offers outstanding educational opportunities in laboratory data collection and analysis, to both the Co-PI and others involved in the project.