AZ Partners in Science - 2013
Using Isotopic Analysis to Determine Historic Husbandry Practices at Los Santos Angeles de Guevavi Mission
Reconstructing Spanish Mission Life
Guevavi was a settlement of the Tohono O’odham people in what is now Southern Arizona. It was first visited by Spanish missionaires in 1691. Marana High School teacher Alexander Ruff is working with Associate Professor Barnet Pavao-Zuckerman, UA School of Anthropology, to reconstruct ranching practices and determine Guevavi’s role in the Spanish mission system.
Alexander Ruff teaches forensic science and biology at Marana High School, located in a semi-rural area of Southern Arizona.
Ruff notes there are many ancient Native American sites in the region, and they have attracted numerous archeologists over the years. Now, however, he’s studying one such site with Associate Professor Barnet Pavao-Zuckerman, UA School of Anthropology, thanks to a Partners in Science award from Research Corporation for Science Advancement.
During his first year of the two-year award, Ruff has been laying the groundwork for isotopic sampling of cattle and goat bones and teeth in the long-abandoned Guevavi settlement of the indigenous Tohono O’odham people.
“This settlement was first visited in 1691 by Jesuit missionaries Eusubio Francisco Kino and Juan Maria de Salvatierra,” Pavao-Zuckerman writes. During the mission period, Spanish colonials introduced Eurasian domestic livestock to the indigenous people.
“What we’re trying to establish is what the livestock were eating and drinking at Mission Guavavi,” Ruff said.
This project uses stable carbon, oxygen, and strontium isotopes from cattle and goat teeth recovered from the mission site. Basically Ruff is helping Pavo-Zuckerman to reconstruct ranching practices. The ultimate goal is to determine the role of Guavavi within the Spanish mission system of southwestern North America.
“We’re trying to figure out if livestock were drinking standing water from the riparian area and we’re using isotopes to do that,” Ruff said. “We’re also looking at whether they were eating C3, C4 or CAM plants.” Those terms refer to the type of photosynthesis plants employ to produce food – C3 is the type of photosynthesis most crop plants use, while C4 and CAM are processes found primarily in native desert plants.
“We’re going to look in the enamel of the teeth, drilling a canal through the enamel and putting the samples through mass spectroscopy. We’ll look at the difference between oxygen 18 isotopes to 16. And carbon 13 and 12. That will give us a good idea of what the cattle were eating and drinking,” Ruff said.
He added that working with Pavao-Zuckerman and his team will allow him to take back to his high school students the notion that spectroscopy and a knowledge of isotopes are important outside of the chemistry lab.
A lot of his students, Ruff said, are living on or near sites abandoned by ancient Native Americans. “So it will be interesting to show them, here’s how people lived and here’s how we find out how they lived and what they ate and what they did. And we can use science to answer a lot of questions that archeologists ask.”