How Volcanic Eruptions Helped the Ancestral Puebloan Culture Flourish

Drastic changes in climate in the sixth century C.E. led the ancient Native American civilization to adopt new technologies

Great Kiva in Chaco Canyon
Climate change led Ancestral Puebloans to relocate, forming denser communities and building grand structures like the great kivas in Chaco Canyon. Sinensky et al. / Antiquity, 2021

In 536 and 541 C.E., volcanic eruptions thrust much of the world into hard times, blocking the sun’s warmth and causing catastrophic crop failures. But a new study published in the journal Antiquity suggests these events had at least one positive effect: namely, contributing to the long-term flourishing of the Ancestral Puebloan culture in western North America. In the decades following the natural disasters, reports Mike McRae for Science Alert, the region’s Indigenous peoples abandoned their small, nomadic communities and began building larger towns with taller buildings.

“Human societies are capable of reorganization to deal with unprecedented climate disruptions,” says lead author R. J. Sinensky, an archaeologist at the University of California Los Angeles, in a statement quoted by Christy Somos of CTV News. “... Ancestral Puebloan farmers living in the arid uplands of what is now the southwestern United States were resourceful and resilient in responding to the most extreme global temperature anomaly to occur within the past 2,500 years.”

For Europeans, 536 marked the beginning of “one of the worst periods to be alive, if not the worst year,” Michael McCormick, a medieval historian at Harvard University, told Ann Gibbons of Science magazine in 2018. The massive eruption of a volcano in Iceland sent thick clouds into the Northern Hemisphere’s atmosphere for 18 months. As Byzantine historian Procopius wrote, “[T]he sun gave forth its light without brightness, like the moon, during the whole year.” Another eruption in 541 extended the crisis, which had rippling effects down the line.

North America suffered in much the same way as Europe. Per CTV News, tree ring measurements from what’s now the southwestern U.S. show that plants endured cold, dry conditions. Faced with disaster, people abandoned their traditional homes.

Duck-shaped vessel
Some Ancestral Puebloans returned to the old practice of pottery making within their new communities. Sinensky et al. / Antiquity, 2021

This drastic change in climate may explain a shift in social organization previously recorded by archaeologists. Prior to the mid-sixth century, people in the region largely lived in dispersed settlements, reports Ruth Schuster for Haaretz. Some survived by farming, while others relied on hunting and foraging.

According to the study, communities developed ties with neighboring groups amid the hardships caused by the climate disaster. These newly forged bonds led to the widespread adoption of once-isolated practices, such as pottery making and turkey cultivation, and ushered in what’s known as the Basketmaker III period. Spanning 500 to 750 C.E., the era was marked by a population boom, as well as technological and lifestyle changes. 

The Ancestral Puebloans’ new, increasingly sedentary lifestyle gave rise to wealth disparities, increasing societal inequality while also bringing about the construction of large, complex buildings. These Indigenous peoples constructed reservoirs and dams for crop irrigation and spread across a large area, developing numerous population centers. By the ninth century, they were creating great kivas, or large circular structures used for ceremonies and political gatherings. Chaco Canyon, a significant center of Pueblo culture from 850 to 1250 C.E., contains numerous great kivas. Per Unesco, the site, in what is now New Mexico, held large public buildings and multi-story houses; it was connected to other Chaco centers through a carefully engineered system of roads.

Today, descendants of the Ancestral Puebloans include the Hopi, Zuni, Acoma and Laguna tribes.

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