Doctoral Dissertation Improvement Grant: Stone Tools and the Brain: A Positron Emission Tomographic Study

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Under the direction of Dr. Nicholas Toth, Mr. Dietrich Stout will collect data for his doctoral dissertation. The goal of the research is to gain insight into the cognitive abilities of early humans and to accomplish this, Mr. Stout will examine the brain activity associated with the production of simple "Mode 1" stone tools. The first such objects appear in the archaeological record ca. 2.5 million years ago and because of their durable nature, over most of the period of human evolution they comprise the primary evidence available to reconstruct behavior. They provide the best, and often, the only insight into early human mental ability. Archaeologists have experimentally replicated Mode 1 tools which consist of simple flakes removed from a larger core of raw material as well as the successively more complicated succeeding lithic technologies. However it is difficult to draw a direct link between these manufacturing techniques and cognitive organization. It is unknown exactly what minimal basic cognitive abilities are necessary to produce simple stone tools and the degree to which early humans were capable of abstract thought. To address this problem, Mr. Stout will conduct Positron Emission Tomography (PET) to determine mental ability by establishing a more direct link between flintknapping and brain activation. Six technologically naive subjects will participate in a longitudinal study. PET images of three experimental conditions (control, novice flintknapping and experienced flintknapping) will be collected. Use of a slowly decaying tracer for imaging will allow experimental tasks to be performed under relatively naturalistic conditions outside a scanner, prior to image collection. Three kinds of data will be collected: PET images, attributes of the tools produced, and videotapes of task performance. The main research goals to be pursued with these data will be 1. dissection of sensorimotor and cognitive aspects of flintknapping skill and 2. exploration of neural, artifactual and behavioral aspects of skill acquisition. PET image data will be used to test specific hypotheses derived from both the literature and from results of a pilot study. Of particular interest will be putative activation of "cognitive planning" areas in novices and potential overlap with classic cortical "language" (Broca's and Wernicke's) areas. The ultimate objective of the research is to apply the results to the archaeology of human origins. A large body of research in the experimental neurosciences now allows patterns of brain activation to be interpreted in terms of mental processes such as motor or strategic planning. In this fashion, imaging of tool replication experiments will provide insight into the necessary information processing requirements of particular flintknapping tasks. This insight may then be judiciously applied to cognitive interpretations of the archaeological record.