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

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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.