The timing, location, and circumstances of the origin of modern humans has long been of interest, and ongoing research continues to improve our understanding of early modern human evolution. However, gaining a clearer picture of when, where, and how modern humans evolved relies on the available fossil evidence, which at present is spread irregularly across geography and through time, and includes mostly partial skulls and teeth with comparatively fewer postcranial bones (i.e., everything below the neck). Considering the limitations of the current fossil record, new fossil evidence is of the utmost importance to the study of modern human origins.

The Middle Awash project has recovered an early modern human partial skeleton, along with additional, more fragmentary human postcranial fossils. These fossils were recovered from a Middle Stone Age archaeological context preliminarily dated to ~100 thousand years, within a locality area named Halibee in the Middle Awash research area in Ethiopia?s Afar Depression. The major goal of this research project was to complete the initial description of the skeletal anatomy of this modern human partial skeleton and the associated postcranial remains. In order to describe the fossils comprehensively and discover how they inform our understanding of human evolution, the initial description was done comparatively by placing the fossils in the context of recent modern human variation, and the variation we see in fossils of genus Homo over the course of the last two million years. Measurements and qualitative observations were collected from the Halibee fossils and from five recent modern human groups, which collectively span five museums. The Halibee fossils are housed in the National Museum of Ethiopia in Addis Ababa, and the modern human skeletons studied for comparison span the Smithsonian?s National Museum of Natural History (groups from northeastern Africa and the Levant), the Raymond A. Dart Collection at University of the Witwatersrand (southern Africa), the 21^st Century Identified Skeletal Collection at the University of Coimbra (western Europe), and the Phoebe A. Hearst Museum of Anthropology at University of California, Berkeley (North American). Comparative data for Homo fossils from the last approximately two million years were collected from the published literature, and include Homo erectus, Neanderthals, pre-modern humans, and chronologically intermediate fossils.

The results of this study include the taxonomic identification of the fossils (i.e., to which species do they belong?). The fossils are assigned to Homo sapiens, based on the presence of some key pieces of the anatomy that researchers agree are diagnostically modern human, including the presence of a chin and a vertically-oriented forehead. The age, sex, and height estimates for the partial skeleton indicate that the individual was a young to middle-aged male of tall stature. Comparisons of the partial skeleton with the recent modern human groups indicate that this individual falls well within the modern human range of variation for most skeletal traits, but falls at the edge of or just outside of the range for a few traits. This is in line with previous findings for other fossils from this approximate time period, which present a combination of modern and pre-modern features.

The description of these previously unpublished fossils contributes to the known fossil record at a critical time and place, near the time of modern human range expansion beyond Africa. The position of the Halibee fossils places them within a population ancestral or closely related to modern humans, which allows us to get at key questions about early human evolution, such as: How does early modern human skeletal anatomy compare to present-day humans? How were early modern humans anatomically different than (or similar to) Neanderthals, and what might this tell us about how evolution has proceeded over the most recent portion (last ~100 thousand years) of our evolutionary history? Considering the relative scarcity of associated postcranial material in this most recent portion of the fossil record, the Halibee fossils constitute a significant addition to the sample available for study, and the description of these fossils makes these data available to researchers focused on specific questions about human evolution.  

This project has supported mentoring and research experience for five UC Berkeley undergraduate students, and has broadened the participation of women and first-generation college students in STEM research. The data collection portion of this project fostered the establishment of positive connections between an early career researcher and museums and research institutions, both domestic and abroad. This work was shared with a public audience via an interview with ?The Graduates,? a publicly-broadcasted radio program on the Berkeley KALX radio station that aims to communicate science to the public while highlighting UC Berkeley graduate student research.

Last Modified: 08/29/2019
Modified by: Marianne Brasil