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

250万到300万年前(Ma)之间的时间一直被认为是古人类进化中最关键的时期之一。在3.0 Ma时，东非和南部非洲的化石记录中出现了多种南方古猿。到了2.5 Ma，南方古猿几乎灭绝了，取而代之的是两个独立的谱系，它们对环境的适应能力截然不同。其中一个血统是我们自己的人，其特征是大脑体积的增加和对物质文化的依赖，这种模式在过去数百万年里一直存在。另一个血统，类人猿，持续了100多万年，以三个物种为代表，它们具有独特的牙齿和面部适应能力，可能会吃硬的或硬的食物。尽管这一间隔具有明显的重要性，但它在化石记录中的代表性很低，几乎没有发现能够揭示这些谱系起源的原因和模式的化石标本。Ledi-Geraru研究项目在一个化石丰富的区域工作，该区域包括这一重要的时间间隔，旨在阐明与南方古猿灭绝和人和类人猿的出现相关的问题。研究人员将把这项工作的结果用于关于原始人血统的公共科学宣传，包括环境差异和原始人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。在过去的十年里，研究人员在埃塞俄比亚的阿法尔地区发现了2.9 Ma到2.4 Ma之间的化石沉积物。从这些沉积物中发现的化石包括一块280万年前的下颌骨，这是已知的人属最早的代表，另外还有一些化石表明，该地区大致同时存在多种原始人物种。此外，Ledi-Geraru研究项目区的几个地点显示，有证据表明，古人类使用石器获取动物组织和资源。Ledi-Geraru项目地点将继续进行古人类学研究，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NSF的法定使命，并通过使用基金会的智力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.