Doctoral Dissertation Research: Modeling hominin variability in Australopithecus africanus

人类学研究的基本目标之一是了解人类的生物学起源和进化，古人类化石记录是这方面的主要数据来源。然而，很难确定，在给定的时间和地点，相对有限和碎片的古人类化石是否代表一个或多个物种。南非的化石属于非洲南方古猿（Australopithecus africanus）。这组化石的多样性被认为代表了不止一个物种，但是对于如何对不同的化石进行分类却没有达成一致意见。确定这一组合的物种名称很重要，因为它会影响对非洲古猿作为我们自己的人属直系祖先的解释，从而影响我们对人属如何以及在何处进化的理解。通过结合系统生物学的方法和发展新的统计方法，本研究将为定义古人类化石物种和解决古人类进化多样性问题提供必要的框架。该项目还将支持对学生的培训和指导，包括来自STEM领域代表性不足的群体的学生，向高中生进行科学推广，以及将通过Morphosource提供的扫描数据。在化石记录中识别物种对于理解人类的进化和多样性至关重要。关于物种概念的文献大量存在，但基于过程的定义不容易应用于化石物种。因此，在假定的假说内的变异水平通常被用来描绘古人类物种，但这些方法建立在一个有问题的假设上，即这些参数在灭绝和现存物种中是可比的。在生物学的其他领域，已经开发出使用样本内变异结构来检测离散物种存在的方法。尽管在人族物种划分上存在持续的争议，但这些方法尚未在人类学中得到应用。非洲南方古猿就是这个问题的例证。解决它的阿尔法分类对解释人类进化至关重要，但它仍然是一个有争议的问题。非洲古猿包含两个或两个以上物种的可能性对人类系统发育和人属进化的解释具有重要意义。本研究的目的是定量模拟现存灵长类动物和古人类的物种变异，以重新评估非洲古猿类群的分类异质性。这将通过使用系统发育比较方法来估计适当的人族变异性零假设模型来完成。数据将通过地标、半地标和基于gis的方法从现存灵长类动物和古人类化石牙齿的三维表面收集。这项研究的数据将使用混合模型和矩阵相关分析提供一个详细的古人类变异性模型。

One of the fundamental goals of anthropological research is to understand humanity's biological origins and evolution, for which the hominin fossil record is a primary source of data. However, it is difficult to determine, for a given time period and location, whether the relatively limited and fragmentary hominin fossils represent one or multiple species. Such is the case for South African fossils attributed to the species Australopithecus africanus. The variability in this assemblage of fossils has been proposed to represent more than one species, but there is little agreement about how to sort the various fossils. Determining species designations for this assemblage is important because it affects interpretations of A. africanus as a direct ancestor of our own genus Homo and therefore our understanding of how and where the genus Homo evolved. By incorporating methods from systematic biology and developing new statistical methods, this research will provide a necessary framework to define hominin fossil species and address diversity in hominin evolution. This project will also support training and mentoring of students, including from groups underrepresented in STEM fields, science outreach to high school students, and scan data that will be made available through Morphosource. The recognition of species in the fossil record is of critical importance to understanding hominin evolution and diversity. A vast literature exists on species concepts, but process-based definitions cannot be easily applied to fossil species. Accordingly, levels of variation within purported hypodigms have typically been used to delineate hominin species, but such approaches rest on the problematic assumption that these parameters are comparable in extinct and extant species. Elsewhere in biology, methods have been developed that use the structure of variance within a sample to detect the presence of discrete species. Despite continued controversy over hominin species delineation, these methods have yet to be employed in anthropology. Australopithecus africanus exemplifies this problem. Resolving its alpha taxonomy is critically important to interpreting human evolution, but it remains a contentious issue. The possibility that A. africanus subsumes two or more species has significant implications for the interpretation of the hominin phylogeny and the evolution of the genus Homo. The goal of this research is to quantitatively model species variation in extant primates and fossil hominins in order to re-evaluate the taxonomic heterogeneity of the A. africanus assemblage. This will be accomplished by using phylogenetic comparative methods to estimate an appropriate null hypothesis model of hominin variability. Data will be collected from 3D surfaces of extant primate and fossil hominin teeth using landmarks, semi-landmarks, and GIS-based approaches. The data from this study will provide a detailed model of hominin variability using both mixture models and matrix correlation analyses.