Collaborative Research: Filling in a temporal gap in hominin evolution

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The Ledi-Geraru Research Project (LRGP) promotes the science of human origins by exploring a region in the Afar of Ethiopia, which contains rare fossiliferous sediments ranging in time from 3.0-2.4 million years ago. The evidence for both behavioral and biological evolution in the hominin lineage is limited during this time period. However, these sediments contain some of the earliest archaeological sites in the world, as well as fossils of human ancestors. New archeological and paleontological data will be collected that provide a better understanding of hominin behavioral evolution, the extinction of Australopithecus afarensis, the origin of material culture in the form of stone tool technology, and the biogeography of ancient mammal species. The investigators will examine the various factors that are driving evolution, such as climate change, to understand the conditions under which biological and behavioral changes occurred in human evolutionary history. The project will engage both K-12 students and the public at large; the immediate field findings will be delivered in a real-time atmosphere through interactive blogs from the field in which each scientist interacts with students from U.S. classrooms. The project is also instrumental in training students from both the U.S. and Ethiopia in a STEM science. During this three-year project, the investigators will collect archaeological, paleontological, and paleoenvironmental data to address behavioral and biological evolution in the hominin lineage in the time period from 2.95-2.5 Ma. In the lower Awash valley of Ethiopia, the last appearance date of A. afarensis at ~2.95 Ma (Hadar), followed by the appearance of stone tools at ~2.58 Ma (Gona) and Homo cf. H. habilis (Hadar) at ~2.35 Ma, have been described as a drastic niche shift for the hominin lineage. This project is examining strata from a period heretofore undocumented in the lower Awash valley. Archaeological excavations are being expanded in locations where artifacts have been previously recovered. Past habitats in which hominins existed will be reconstructed with multiple methods including mammal community structure, utilizing mesowear and stable isotopes for mammalian diets, ecomorphology to retrodict mammal locomotor patterns, and analyses of botanical remains. Data recovered will be compared to hominin, faunal, and botanical information from localities near the LGRP that encompass time before and after this interval to develop a regional, representation of the paleoenvironment and species turnover across time and space. Subsequently, these data will be compared to sites beyond the lower Awash region to better understand East African evolutionary and biogeographical patterns.