The origin of our species, Homo sapiens, is one of the most contentious and poorly understood topics in the study of human evolution. While both fossil and genomic evidence supports an African origin for Homo sapiens, fossil evidence from the appropriate time range is scanty. Fossils of genus Homo were encountered in Middle Pleistocene sediments in the Kapthurin Formation, Kenya, but operations were suspended due to the start of the rainy season, which renders work impossible. NSF funds will support a rescue operation to recover more fossils, to determine their precise stratigraphic position, and to prevent destruction of the site.

The nature of the events leading to the origin of our species is of one of the critical unresolved issues in the study of human evolution today. These events are of intense interest both to scientists and to the general public. They cannot be understood without new African fossils such as those provided by this research. This research will provide training opportunities for one postdoctorate student and two graduate students from the University of Connecticut, as well as ten Kenyan technicians and local participants. Results will be shared with the local community including children at two local primary schools. Results will be disseminated in both scholarly and popular media.

Project Report

Hominin skull fragments were discovered at a site near the shore of Lake Baringo, Kenya, in August, 2010. The skull fragments appeared to have archaic features and were lying on the surface of a volcanic deposit dated to 235,000 years by the Argon-Argon method. Supported by NSF BCS 1103441, an operation to rescue the hominin remains was conducted From December 14, 2010, to January 15, 2011. The site was thoroughly mapped, the geology examined, and a surface collection and sweep made of an area of about 475 m2 downslope of the initial find spot. Swept sediment was sieved through ¼ inch mesh, producing a collection of 103 stone artifacts, including backed crescents that probably date to the early Holocene, a dozen potsherds, human bone and tooth fragments, and bone and shell fragments representing various mammals, reptiles, and fresh water oysters. A trench of 16 m2 was opened at the hominin find spot, and much of a complete human skeleton was discovered. It lay on its left side, head toward the NNE, knees flexed. The articular ends of the long bones are poorly preserved, and smaller elements were dispersed over an area of about 6 m2. Evidence of substantial disturbance by burrowing termites was observed. Cranial fragments, the bones of both arms and legs, many hand and foot bones, a clavicle, vertebrae, and a fragmentary pelvis were preserved in plaster jackets, recovered, and transported to Nairobi, where they were deposited in the hominin vault at the National Museums of Kenya. Although no traces of a burial pit were observed in excavation, discovery of backed crescents and potsherds in the trench near the skeleton led to the supposition that the human bones were of Holocene date, and were intrusive into the 235,000 year old volcanic deposits. Subsequent direct dating of the skeleton by the Uranium-series method indicates that its age is no greater than 12,000 years. Its date renders the skeleton important for the information it can provide about the recent ancestry of East Africans. It is currently undergoing cleaning and stabilization at the National Museums of Kenya, and will be described and analyzed when this process is complete. Four University of Connecticut graduate students, one postdoc, and numerous Kenyans received training as a result of this grant. Project members engaged in substantial outreach to the local community and provided support to its primary school.

National Science Foundation (NSF)
Division of Behavioral and Cognitive Sciences (BCS)
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Carolyn Ehardt
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University of Connecticut
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