With National Science Foundation support, Dr Steve Wolverton and a team of archaeologists, analytical chemists, and proteomic biologists will do burial experiments with modern cooking pottery and research on archaeological pottery to evaluate the role of variability in climate, soil, and ceramic paste on the preservation of food protein residues. This project builds on previous research funded by NSF in which the same team addressed which types of solvents and physical conditions work best for extraction of protein residues from cooking pottery. Protein residues offer distinctive advantages over other types of food residues in that they bind to clay in pottery walls, which enhances preservation, and that proteins can often be identified to species or perhaps even to tissue. An important hurdle is that factors that mediate long-term preservation of protein residues have not been well studied, the focus of this project in both experimental and archaeological settings.
This research is important because it will provide a new set of tools which will allow archaeologists to examine previously inaccessible aspects of past culture. It will help to reconstruct past subsistence patterns and provide insight into how populations adapted to the environments in which they lived.
Residue analysis in general has lacked for detailed studies of method development. In terms of intellectual merit, the high potential of protein residues to provide precise data on what people cooked in pots in the past makes experimental replication of methods an essential process. Production of reliable analytical approaches and knowledge of conditions in which proteins are more and less likely to preserve will greatly amplify or current knowledge of protein residues from ancient foods.
This project involves students and professionals from Argentina and the United States, from a museum (Argentina), a non-profit public-education/archaeological research firm (US), and universities (US). The nature of the work is highly interdisciplinary, incorporating professionals with specialties in archaeology, ceramic petrography, material science, chemistry, and biology. The project will fund a graduate student for two academic years to work with this interdisciplinary team. Results will be published in scholarly journals and will be presented at academic conferences and in classroom settings.
This project represents the second phase in a series of experiments for developing and refining methods for extracting food protein residues from archaeological pottery. Very little is known in archaeological residue chemistry as to how biomolecules behave in terms of preservation over time. For this protein experiment, we buried experimental cooking pottery with food and pure protein residues to ascertain how well residues survive over months and years in a variety of microenvironments. What have learned is that protein residues are exceptionally difficult to study from cooking ceramics because not only are the residues the result of cooking, which modifies proteins, the residues have been weathered over time. Even over months and years, there is rapid degradation of protein residues, which makes extraction and identification a real challenge. That said, there is promise for the study of protein residues, but it may need to be accomplished through very targeted approaches that seek to extract and recognize particular residues of particular proteins. This is because proteins vary in terms of preservation over time, and all cooking residues occur in very trace amounts. Thus, our method development study is important; it is tempting to simply apply biomolecular chemistry in the same ways that applied scientists do to contemporary samples. Our samples are different, and we have learned a lot about what does and does not work. Many of our results over the last three years accentuate what is not possible to acheive, so-called negative results. We are presenting the results of our experiments at the 2015 Society for American Archaeology conference, developing a number of scholarly publications, and hosting a residue workshop at the University of North Texas for graduate students from the University of New Mexico to learn our approach in May of 2015. The most important impact of our research, however, is that we are making it very clear that archaeologists must design chemistry approaches that are tailor-made for examination of pottery food residues if we are to trust the validity of results when residues are identified from archaeological pottery.