Isotopes in Livestock Teeth Shed New Light on Ranching Practices at Spanish Missions

April 2, 2016

Isotopes in Livestock Teeth

Domesticated livestock, including cattle, sheep, goats, pigs, and chickens were introduced to southwestern North America in the late 17th century by Spanish missionaries. Historical and archaeological evidence indicates that Native American reactions to these introduced animals were mixed. In some cases, Native peoples initially rejected livestock. Large livestock, particularly cattle, have the potential to radically alter landscapes, and it appears that Native peoples quickly understood that risk. In the arid Southwest, introduced water-intensive livestock represented a threat to drinking water. Native peoples often complained about the animals muddying and fouling the water in riparian zones.

However, historical documents indicate that livestock flourished at most missions by the mid-18th century. Recent archaeological research suggests that cattle ranching became the dominant economic activity of missionized Native American groups by the turn of the nineteenth century, but much of the details of ranching practices in the region are not yet known. In particular, it is not known how herds were managed on the landscape, or whether missions were involved in trading or selling livestock with other missions, presidios, secular ranches, or mining communities.

These issues are important to understanding the experiences of Native Americans under missionization, the role of missions in regional economies, and the impact of early ranching on southwestern landscapes. Traditional historical narratives portray missions as backwater frontier isolates that were disconnected from the rest of the colonial system. However, recent research in other regions of North America indicate that Native American labor at Spanish colonial missions was critical to the success and support of broader colonial programs.

Traditional zooarchaeological analyses yield critical data including species, skeletal element representation, age/sex profiles, and butchering practices, but cannot address much more specific questions regarding husbandry practices, such as foddering or grazing regimes, landscape use, or the movement of livestock through trade networks. Isotopic analyses of zooarchaeological bone and teeth can provide information on the diet and movement of animals in the past, particularly when used in concert with traditional zooarchaeological data, observation of modern ranching practices, and documentary descriptions of historic landscapes and ranching practices. However, until this research project, isotopic techniques were untested on mission-period livestock remains in the Sonoran Desert environment.

The data, while inconclusive in some respects, support the hypothesis that livestock ranching in the mission period focused on less labor-intensive strategies such as free-ranging, rather than labor-intensive foddering practices. Coupled with ethnohistoric data, it appears that missions employed water management technologies to bring water to free-ranging cattle. While free-ranging livestock may have required less time and labor input on the part of missionized Native Americans than foddered livestock, maintenance of water storage and diversion systems would have been a significant labor sink. However, the presence of water diversion features in the region prior to the arrival of Europeans, and perhaps as early as 1500 BCE, may suggest that indigenous knowledge shaped water management strategies in the colonial period.

This research project, funded by the University of Arizona Vice President for Research's Faculty Small Grants Program, raises several important future avenues of inquiry that will help elucidate livestock ranching practices in the historic period. Funding will be sought to pursue these avenues, with particular emphasis on subjecting the archaeological samples to isotopic analyses.

Shown above, top: Photomicrograph of a c. 1800 cattle (Bos taurus) tooth from Mission San Agustín de Tucson. The light colored region is where a sample was removed for isotopic analysis. Bottom: Anthropology Ph.D. candidate Deanna Grimstead removing samples from livestock teeth for isotopic study.

Photos by Barnet Pavao-Zuckerman.