With support from the National Science Foundation, Dr. Sally McBrearty and a team of collaborators will conduct three seasons of field work in Kenya to examine changes in stone technology and ancient environment. The project focuses upon the Kapthurin Formation, a well dated Middle Pleistocene sequence that is rich in stone artifacts, fossil bone, fossil plants, and other paleohabitat indicators.
The origin of our species, Homo sapiens, occurred in Africa during the time interval spanned by the Kapthurin Formation, and the appearance of early Homo sapiens coincides with the archaeological change known as the Acheulian to Middle Stone Age transition. Acheulian technology, characterized by handaxes, disappeared, and was replaced by Middle Stone Age artifacts such as points and other small flake tools. This shift reflects a profound behavioral reorganization that may be the product of the increased cognitive ability of Homo sapiens. Alternatively, the technology itself may have played a role in the construction of the unique human adaptive niche, leading to the anatomical changes seen in the human fossil record. Thus the timing of events, and the environmental circumstances under which they occurred, are critical to understanding the processes leading to the origin of our species. The aims of the project are to identify variations in technology and use of the landscape, to detect any changes through time, and to establish the temporal framework for these developments.
The research will contrast two time intervals in the Kapthurin Formation, the first dating to 550,000 - 509,000 years ago, the second to 509,000 - 235,000 years ago. Previous work in the older time interval provides a baseline to which results from the current work in the younger interval can be compared. Excavations at two sites in the younger time interval will provide information on the density and characteristics of artifacts and fossil bones. Geologic mapping will furnish important information on the ancient topography and environment which will be integrated using a Geographic Information System (GIS). The ancient vegetation will be documented by the study plant fossils, pollen, grass cuticles, phytoliths, and the stable isotope content of mammalian fossil teeth. Fossil footprints of a variety of animals at one of the excavated sites will be conserved and cast, and footprint identification will provide unique insight into the faunal community present at the time the site was occupied. Correlation of specific tool types and habitat features will be sought to assess environmental explanations technological variability. Patterns discovered will be compared to those of the older time interval to assess the nature and degree of change through time. This research will provide critical new information about the nature of the processes leading to the origin of Homo sapiens, a key issue of debate in human evolutionary study today. The project is conducted in collaboration with the National Museums of Kenya. It will contribute to the training of both American and Kenyan students and the enhancement of museum collections and infrastructure. American, European, and Kenyan scholars will participate in data collection, analysis, and dissemination of results.
