Collaborative Research: Hominin diversity, paleobiology, and behavior at the terminal Pliocene

250万到300万年前这段时间一直被认为是人类进化中最关键的时期之一。3.0 Ma时，在非洲东部和南部的化石记录中出现了多种南方古猿。到2.5亿年前，南方古猿大部分灭绝了，取而代之的是两个对环境适应能力截然不同的独立谱系。其中一个谱系是我们自己的人属（Homo），其特点是大脑体积增大，对物质文化的依赖在过去几百万年里一直持续存在。另一个谱系，傍人，持续了100多万年，由三个具有独特牙齿和面部适应能力的物种代表，可能会吃坚硬或坚硬的食物。尽管这段时间的重要性显而易见，但它在化石记录中表现得很少，而且很少发现化石标本，可以阐明这些谱系起源的原因和模式。Ledi-Geraru研究项目在包括这一重要时间间隔的化石区开展工作，旨在阐明与南方古猿灭绝和人属和类人猿出现有关的问题。研究人员将把这项工作的结果用于人类谱系的公共科学推广，包括环境变化和人类适应之间的关键关系。该项目还将促进国际合作和学生培训。在过去的十年中，研究人员在埃塞俄比亚阿法尔地区发现了距今2.9至2.4 Ma的化石沉积物。从这些沉积物中发现的包括280万年前的下颌骨，这是已知最早的人属代表，以及其他化石，表明该地区大约在同一时间存在多种人类物种。此外，在Ledi-Geraru研究项目区域的几个地方，有证据表明人类使用石器工具来获取动物组织和资源。继续的古人类学研究将在Ledi-Geraru项目遗址进行，以恢复更多的化石和考古材料，并更好地了解人类行为与环境背景之间的关系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The period of time between 2.5 to 3.0 million years ago (Ma) has long been considered one of the most critical in hominin evolution. At 3.0 Ma, multiple species of Australopithecus are represented in the fossil record across eastern and southern Africa. By 2.5 Ma, Australopithecus mostly died out, and in its place evolved two separate lineages with very different adaptations to the environment. One lineage is our own, Homo, characterized by a pattern of increased brain size and dependence on material culture that has persisted over the last several million years. The other lineage, Paranthropus, lasted over 1 million years, and was represented by three species with unique dental and facial adaptations for potentially eating tough or hard foods. Despite the obvious importance of this interval, it is poorly represented in the fossil record and few fossil specimens have been found that can shed light on the causes and patterns of the origins of these lineages. The Ledi-Geraru Research Project works in a fossiliferous region that includes this important time interval and aims to illuminate the issues relevant to the extinction of Australopithecus and the emergence of Homo and Paranthropus. The investigators will use the results of this work in public science outreach about the hominin lineage, including the critical relationship between environmental variance and hominin adaptations. The project also will foster international collaborations and student training. In the last decade, the investigators have identified fossiliferous sediments in the Afar region of Ethiopia that range from 2.9 to 2.4 Ma before present. Finds from these sediments include a 2.8 million year old mandible that is the earliest known representative of the genus Homo, and additional fossils suggesting that there were multiple hominin species existing at roughly the same time in the region. In addition, several localities in the Ledi-Geraru Research Project area show evidence that hominins were using stone tools to gain access to animal tissues and resources. Continued paleoanthropological research will be conducted at Ledi-Geraru Project sites to recover additional fossil and archaeological materials and better understand relationships between hominin behaviors and environmental contexts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.