Glazed pots made by Southwest Indian tribes from around 1300 to 1600 were a lot like the Amazon.com shipping boxes of today. They were used to transport items to and from locales all over today’s Southwestern United States, and they often were reused many times.
“The classic view that each woman made and used her own pots just isn’t right,” says SFI Professor and Science Steering Committee Chair Doug Erwin. He says glazed pottery shards from a broad region often are found at a single archaeological site. (Doug is Senior Scientist and Curator of Paleobiology at the Smithsonian Institution.)
Doug, Peter Sadler (UC Riverside), Linda Cordell (School of American Research), and a small group of researchers from paleontology and archaeology are firing up interest in applying correlation methods to questions about the social and trade networks among the Pueblo Indian groups from the 14th to the 17th century.
A January 17 working group meeting at SFI brought together eight interested researchers to discuss whether data sets about glaze ware unearthed during archaeological digs in the northern Rio Grande region could be analyzed to improve archeologists’ understanding of such interactions. It was the second such meeting on the topic. Sadler, a geologist, applies probabilistic algorithms to find optimum solutions in large search spaces, resulting in high-resolution temporal frameworks of the fossil and archaeological records.
Pottery styles and painting methods have beginnings and ends, explains Doug. The idea is to feed large data sets about the pottery types found at individual archaeological sites, as well as tree-ring and carbon-14 dates, into Stadler’s computer program to identify relationships and chronological overlaps and divide archaeological time into smaller chunks.
Traditional archaeology considers time in relatively long intervals, often several centuries. If researchers can use pottery evidence to divide time into narrower intervals, a richer investigation of trading networks and possibly migration pathways can be accomplished, he says.
“Once you do that, you might be able to look at 50-year windows, and you can do a network analysis and begin to look at interaction networks between pueblos and people,” Doug says.
“If you had three locations, that would be easy,” he adds. “As you get more and more sites, it becomes much harder to handle the data.”
Sadler’s group is adapting constraint-optimization algorithms developed at UC Riverside to simultaneously analyze multiple data sets to find best- t solutions. The heuristic search methods are borrowed from the traveling salesman problem – finding the shortest route between many cities by visiting each city only once. As the number of cities grows, the number of possible sequences grows exponentially.
Because pottery artifacts are preserved only sporadically within their true time and space ranges, the archaeological record has many holes and disagreements.
“Our challenge is to nd the global sequence of ancient events that best ts the evidence from all the local exca- vations,” says Sadler.
So far there is great interest in and energy around the approach among the participants, says Doug. Much of the early discussion has focused on construction of archaeological data sets, he says.
Future workshops are expected to build on this discussion and lead to the formation of a modeling network.