Past Research Highlights
April/May 2006
A New Hominid Cranium from Gona, Afar, Ethiopia
Gona Palaeoanthropological Research Project, CRAFT Stone Age Institute, Indiana University
Scientists conducting palaeoanthropological field research at Gona, in the Afar Administrative State of Ethiopia have discovered a significantly complete cranium of a human ancestor estimated to be Middle Pleistocene in age. The new hominid was discovered at Gawis (pronounced "gow-wees"), in the Gona Paleoanthropological Research Project study area of Ethiopia. The discovery was reported by Sileshi Semaw, Director of the Gona Project, who is based at CRAFT Stone Age Institute, Indiana University, USA.
Asahmed Humet holding the Gawis cranium, shortly after he discovered it on
February 16, 2006.
The new cranium from Gawis appears to be intermediate between the earlier Homo erectus and later Homo sapiens and may be sampling a single lineage. At the discovery site and nearby areas, significant archaeological collections of Late Acheulean stone tool-making tradition and numerous fossil animals were found, opening a window into an intriguing and important period in the development of modern humans. The southwest portion of the project area near the Gawis River contains the youngest part of the archive which is estimated to the Middle Pleistocene. Most of the sediments containing the cranium are sands and silts, not datable by standard geologic methods. However, the region contains many active and recently active volcanoes that erupted periodically, blanketing the local landscape with thin, gray-colored layers of volcanic ash. These volcanic ash layers hold the key to dating the Gawis cranium and associated stone tools. Some ash layers in the Gona project area can be directly dated by the 40Ar/39Ar method, and others, by virtue of their distinctive chemical composition, can be matched to correlative dated layers outside the Gona area providing the opportunity to make this one of the best-dated human ancestors notes Jay Quade, Gona project geologist.
The Discovery of the Gawis Cranium and its Significance.
The cranium was found by Asahmed Humet (project member) on February 16, 2006 while he and project scientists were conducting archaeological and geological reconnaissance survey in the Gawis river drainage basin in the Afar Regional Administration of Ethiopia. The cranium was found in a small gully at the base of a steep slope of soft sediments from which it had recently eroded. The specimen includes the braincase, upper face, and upper jaw. Several surface exposed stone tools were found at the hominid site. Additional contemporary stone tools excavated from the same stratigraphic level near the hominid site include Late Acheulian artifacts. A diversity of fossil animals including pigs (two types), zebras, elephants, multiple types of antelopes, small carnivores including cats, and numerous rodents were found at the same stratigraphic level as the Gawis cranium.
Semaw says that "I am thrilled to have a complete cranium discovered from Gona that can provide key information for understanding the variation that existed during the Middle Pleistocene" Scott Simpson, the project paleontologist added that "a good fossil provides anatomical evidence that allows us to refine our understanding of evolution. A great fossil forces us to reexamine our views of human origins. I believe the Gawis cranium is a great fossil."
Left: Dr. Scott Simpson (Case Western Reserve University) and right: Dr. Jay Quade (Desert Lab and the University of Arizona), rejoining the two halves of the Gawis cranium.
The Gawis cranium comes from a time of transition to modern humans from African Homo erectus that is poorly known. The fossil record from Africa for this period is sparse and most of the specimens are poorly dated. The few fossil crania that are known from the Middle Pleistocene of Africa present a narrow view of the range of potential anatomical variation during this period.
The Gawis cranium provides us with the opportunity to look at the face of one of our ancestors. Additionally, this fossil links us with the past by showing a face that is recognizably different and more primitive than ours. The face and cranium of this remarkable fossil are recognizably different from that of modern humans but it bears unmistakable anatomical evidence that it belongs to our ancestry. The form of the face and the brain are among the best means for exploring the evolutionary path of humans and the Gawis cranium preserves both areas. Work is in progress by the Gona team to determine the age of the cranium and associated archaeology, and to understand its evolutionary relationships with others known during the Pleistocene. Semaw concluded by saying that "I am happy that the Gona project succeeded to make a new hominid discovery from this least known time period in human evolution. Gona is a wonderful site and Ethiopian palaeoanthropology has a lot more to offer to the world. We will keep our heads up and continue our work, and I am optimistic that we will be rewarded with more thrilling discoveries for years to come."
Previous Discoveries by the Gona Palaeoanthropological Research Project
The Gona project area has sediments that span the last 5.6 million years - a period that has witnessed many evolutionary and technological changes in human history and Gona has already provided evidence that allow a better understanding of those changes. The Gona archaeological sites are known for the discovery of the oldest excavated stone tools in the world dated to 2.6 million years ago. Early in 2005, members of the Gona Project announced the discovery of hominids assigned to Ardipithecus ramidus, among the earliest hominid genus in Africa dated between 4.5-4.3 million years ago.
Support
The research permission for the work in the Afar is granted by the Authority for Research and Conservation of Cultural Heritage (ARCCH) and the National Museum, the Ministry of Culture and Tourism of Ethiopia. CRAFT Stone Age Institute and Friends of CRAFT, Indiana University supported all aspects of this research. The fieldwork was supported by a major grant from the L.S.B. Leakey Foundation. Additional funding was provided by the National Science Foundation (grant to Researching Hominid Origins Initiative-RHOI).
For more information contact:
Dr. Sileshi Semaw (Archaeology)
CRAFT Stone Age Institute
1392 W. Dittemore Rd., Gosport, IN, 47433
Tel. (812) 876-0080, Ext. 210
E-mail: ssemaw@indiana.edu
Dr. Scott Simpson (Paleontology)
Department of Anatomy, School of Medicine, Case Western Reserve University
10900 Euclid Avenue, Cleveland, Ohio 44106-4930
Tel. (216) 368-1946
E-mail: sws3@cwru.edu
Dr. Jay Quade (Geology)
Department of Geosciences, University of Arizona, Tucson, AZ 85721
Tel. (520) 792-0454
E-mail: jquade@geo.arizona.edu
Dr. Michael J. Rogers (Archaeology)
Department of Anthropology
Southern Connecticut State University
501 Crescent Street
New Haven, CT 06515-1355
Tel. (203) 392-5677
E-mail: rogersm1@southernct.edu
