Background on the
National Science Foundation Research Project

“Understanding Hunter-Gatherer Grinding
Technology Through Experimentation”

In August 2007, the San Diego Archaeological Center was awarded its first National Science Foundation (NSF) grant of $73,140 for archaeological research. The aim of the two-year project is to improve our understanding of how and why grinding tools were used during the past 9,000 years of human history. San Diego County is used as a case study, but the results are expected to have applications worldwide.

Dr. Margie Burton, Center Research Director, is Principal Investigator and leads a consulting team of Native Americans and archaeologists including Clint Linton, Mel Vernon, Dr. Jenny Adams, Tammy Buonasera, Dr. G. Timothy Gross, and geologist Dr. Patrick Abbott. As part of the project, the public will be invited to participate in grinding experiments using replicated milling tools to process acorns, chia seeds, and dry clay. The first set of grinding experiments were conducted in February 2008. The project grant provides funding for new lab equipment at the Center, including a boom-mounted stereomicroscope with digital camera. This new microscope will be used to photographically document the working surfaces of experimental and archaeological milling tools and will be made available for future use by other researchers. Center Director Cindy Stankowski noted that this first NSF grant is central to the expansion of the research capabilities of the Center and will have broad implications for collaborative and comparative research with other projects relating to the study of hunter-gatherer societies.

Volunteers later removed the shells from the acorns in preparation for future grinding sessions for the research project.

Project consultants Dr. Jenny Adams, Desert Archaeology, Inc., (right - shown with Mel Vernon) and Tammy Buonasera, University of Arizona, (above) traveled from Tucson, Arizona to help organize and supervise the session.

During the February grinding session and subsequent sessions held in March and April, volunteers were asked to record the time they spent grinding, the amount of material processed, and other observations related to their use of the replica tool set. Compilation of this data is beginning to yield results that suggest patterned differences in the relative efficiency of different grinding tool shapes for processing different materials. For example, substantially different quantities of acorns and small seeds appear to be processed during a given time interval using a mortar and pestle compared to a flat metate and mano set. Experiments contined into the Fall of 2008 and included 27 replica tool sets.

Over 90 volunteers have participated in the experiments to date. According to volunteer Joan Ho, who accompanied her daughter Eudoria Lee, (shown at right) “We both had a great experience learning about how the Native Americans lived through this hands-on grinding project. I think this family and community involvement component is such an eye opening experience for youngsters like Eudoria to experience first hand how an archaeologist works and thinks.”

Replica tool sets for the grinding experiments were manufactured expressly for the project by Center Research Associate Dr. G. Timothy Gross.

The replica tool sets were photographed macroscopically and microscopically prior to use. This will allow surface wear resulting from known processing activities to be described and documented when the experiments are complete.