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起源和进化，对此人类化石记录是主要的数据来源。然而，在给定的时间段和地点，很难确定相对有限和支离破碎的原始人化石代表一个物种还是多个物种。南非的化石就是这样的，这些化石被认为是非洲南方古猿。这种化石组合的可变性被认为代表了不止一个物种，但对于如何对各种化石进行分类，几乎没有达成一致意见。确定这种组合的物种名称很重要，因为它影响到对非洲金线虫作为我们自己的人属的直系祖先的解释，从而影响了我们对人属如何以及在哪里进化的理解。通过结合系统生物学的方法和发展新的统计方法，这项研究将提供一个必要的框架，以定义人类化石物种和解决人类进化中的多样性问题。该项目还将支持对学生的培训和指导，包括对STEM领域代表性不足的群体的培训和指导，对高中生的科学宣传，以及将通过Morphosource提供的扫描数据。化石记录中物种的识别对于理解原始人的进化和多样性至关重要。现有大量关于物种概念的文献，但基于过程的定义并不容易应用于化石物种。因此，所谓的低等生物内的变异水平通常被用来描述原始人物种，但这种方法依赖于一个有问题的假设，即这些参数在灭绝和现存物种中是可比较的。在生物学的其他领域，已经开发出使用样本内的方差结构来检测离散物种的存在的方法。尽管对原始人物种的划分仍存在争议，但这些方法尚未应用于人类学。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于解释人类进化至关重要，但它仍然是一个有争议的问题。非洲金线虫包含两个或多个物种的可能性对于解释人的系统发育和人属的进化具有重要的意义。这项研究的目的是对现存灵长类动物和古人类的物种变异进行定量建模，以重新评估非洲金线虫组合的分类异质性。这将通过使用系统发育比较方法来估计人的可变性的适当的零假设模型来实现。数据将使用地标、半地标和基于地理信息系统的方法从现存的灵长类和古人类牙齿的3D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来提供人的可变性的详细模型。

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.