A Landscape Approach to Archaeological Variability at the Acheulian to Middle Stone Age Transition in the Kapthurin Formation, Kenya

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With the support of the National Science Foundation a team of archaeologists and geologists led by Dr. Sally McBrearty will carry out three seasons of field work in the Baringo region of Kenya. The team will investigate how Middle Pleistocene landuse patterns changed with the appearance of Homo sapiens in the East African Rift Valley about 300,000 years ago. They will focus upon three stratigraphic intervals within the Kapthurin Formation, where sites containing Acheulian artifacts, thought to have been made by Homo erectus, are interstratified with those containing Middle Stone Age artifacts, thought to have been made by Homo sapiens. The ancient topography will be reconstructed by geological mapping with laser transit, and a three-dimensional model of each target interval will be reconstructed using GIS software. The ancient plant and animal communities will be documented through the study of mammalian and plant fossils, as well as fossil soil and fossil tooth stable carbon and oxygen isotopes. Surface collection, trial trenches, and horizontal excavation at two sites per stratigraphic interval will provide evidence for early human behavior in the form of stone tools and fossil bone which has been processed for food by early hominids. Patterns of association of these behavioral traces of with topographic features and plant communities will be sought for each target interval. A change in landuse patterns with early Homo sapiens, reflecting greater cognitive abilities, technical competence, and geographic range, can be predicted on anatomical and archaeological grounds, but the evidence to date has been drawn from widely dispersed sites which are not well dated. The Kapthurin Formation is confined to a single depositional basin, and the ages of the stratigraphic intervals to be studied are well calibrated by the 40Ar/39Ar dating method. Any landuse patterns detected in the three stratigraphic intervals will be compared to assess the nature and tempo of change through time. Dr. McBrearty and her collaborators will focus on five questions: 1) Is there a detectable change in landuse patterns between the Acheulian and Middle Stone Age? 2) Did Middle Stone Age hominids use a broader array of microhabitats than Acheulian hominids, such as uplands and distal floodplains, in addition to stream and lakeside settings? 3) Were Middle Stone Age hominids able to range further from sources of water or raw material for stone tool making than Acheulian hominids? 4) Were either Acheulian or Middle Stone Age tool makers designing specific implements to exploit particular habitats? 5) How does the competence of Acheulian hunters compare with hunters of the Middle Stone Age? This research is important because it will illustrate the nature of the behavior of the earliest members of Homo sapiens and illuminate some of the processes leading to the origin of our species.