Under the supervision of Dr. Mary C. Stiner, Tammy Buonasera will study changes in the functions of ground stone artifacts from male and female graves from the San Francisco Bay Area of California spanning the mid- to late Holocene (ca. 6000 B.P. to 200 B.P.). Because ground stone milling tools are essential for intensive food processing, they have long played an important role in archaeological interpretations of resource use and the organization of female labor. However, not all ground stone artifacts were used for food processing; some ground stone artifacts had other purposes such as the preparation of ritual or medicinal substances, pigment processing, hide working, the production of beads and ornaments, use as vessels, or as wealth and status markers. This study will employ three different techniques to evaluate the breadth of, and changes in, the functions of ground stone tools during the mid- to late Holocene in central California: Use-wear analysis (both microscopic and macroscopic), absorbed organic residue analysis, and morphological analysis.
Some researchers have proposed that an increasingly rigid and pronounced sexual division of labor developed among complex hunter-gatherers in central and southern California. Others have argued that increasing social stratification should lead to a decreased emphasis on a division of labor based on gender. Differential representation of certain forms of ground stone artifacts (some with very high manufacturing costs) and evidence for uses related to food processing, manufacturing, or ritual activities will be the basis for evaluating these hypotheses. Of particular interest is the relation to women's status with decreasing mobility and increasing social complexity.
In addition to improving knowledge of long-term social changes among Native California societies, this research may make broader contributions to understanding developmental trajectories of a sexual division of labor. Central California is among the few areas worldwide where a level of political complexity typically associated with horticultural or agricultural societies is known to have developed among hunters and gatherers. As such, it offers a unique economic context in which to study the effects of a developing hierarchy on men's and women's activities and status.
This research will provide training opportunities for one or more graduate students and will foster collaboration between several different institutions (the University of Arizona, the Institute for Integrated Research in Materials, Environments, and Society at CSU Long Beach, The San Diego Archaeological Center, and CSU San Jose). Results of ground stone analyses will be shared with the Muwekma Ohlone Tribe, and will be more widely disseminated through publication in appropriate scholarly journals and through presentations at regional and international meetings. Finally, photomicrographs of use-wear will be posted on a free archaeological data sharing website to help improve the transparency and reliability of use-wear interpretations.
Project Outcomes This study analyzed grave-associated ground stone milling tools (mortars, pestles, manos, and metates) from the southern San Francisco Bay Area and employed several techniques (use-wear analysis, morphological comparisons, and organic residue analysis) to investigate potential distinctions in artifact association, manufacturing effort, and use over approximately 6,000 years of prehistory. Morphological and use-wear analysis formed the core of this study. Organic residue analysis can identify the use and processing of specific resins or adhesives, which may render certain perishable technologies (basketry hoppers attached to mortars) or degraded embellishments (bead appliqué) visible, but provided equivocal data on food processing. Ground stone morphologies, patterns of use-wear, and ways in which these artifacts were interred with people changed between the earliest and the latest periods analyzed in this study. A larger proportion of the earliest graves had ground stone associations, although milling tools tended to be less formalized than many Late period associations. Late period burials contained several new types of formalized mortars and pestles while some older forms were retained. Significant variation was observed in the manufacturing costs and the range of use-wear associated with different types of ground stone. In general, use-wear on many smaller less "finished" or less costly artifacts indicates a wider range of applications, while large, finely finished mortars and pestles may have been used in more restricted ways. An overtly symbolic dimension to some ground stone seems to emerge during the late Holocene with the addition of highly formalized and expensive flower-pot mortars, very long shaped pestles, and some mortars with additional embellishments such as shell bead appliqué, or red, black and white designs painted on their exteriors. Differences in the representation of some of these forms in male and female graves over time may reflect changes in the roles of women and men in community ritual and politics. Intellectual Merit Historical trends in research objectives, along with assumptions about the entirely mundane character of ground stone tools, have caused much of the variability and many "extra-utilitarian" aspects of these artifacts to be overlooked. Results from this study will help to expand the types of data that are typically mined from ground stone tools. Analysis has focused on what these tools can tell us about potential changes in tasks, statuses, and community roles among women and men. The sample spans a time frame that encompasses earlier, more mobile and presumably more egalitarian hunter-gatherer populations, and later, more sedentary nonegalitarian hunter-gatherers who were dependent on the storage and processing of acorns and other plant resources. Comparisons through time will contribute knowledge about the range of social and economic variability that existed among prehistoric hunting and gathering societies. Finally, funding from this study allowed 10 samples of human bone to be 14C dated at the University of Arizona AMS facility. In addition to providing information on the temporal span of some mortar types, several dates are also salient for reconstructing regional settlement patterns because they indicate earlier and longer term use at two important sites in this area. Broader Impact This project provided collaborative experiences for the co-PI with researchers at several institutions. Funding from this grant allowed for extensive photo documentation of microscopic and macroscopic patterns of use-wear on several types of mortars and pestles over time. Photomicrographs illustrating different use-wear patterns will be uploaded onto a digital database such as "OpenContext" and listed by artifact type, material type, context and interpretation to expand the comparative base of use-wear patterns and to increase the transparency of use-wear interpretations.
