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Condors soar over Peru’s Colca Valley, a stunning landscape with intricate microclimates along its varied elevations.

The Indigenous peoples of the region still use stepped agricultural terraces that cross the hillsides. How did the creation of these terraces a thousand years ago relate to a dramatic shift in climate and a chaotic period of war?

��ñ�� Associate Professor of Anthropology BrieAnna Langlie received a three-year National Science Foundation grant for $292,000 to answer this question, in partnership with bioarcheologist Matthew Velasco at Cornell University and Geographic Information Systems specialist Lauren Kohut from Winthrop University.

“We are looking at the relationship between climate change, crisis, wealth and inequality,” said Langlie, a paleoethnobotanist who focuses on ancient agriculture, particularly plants. “As we confront similar circumstances in the Colca Valley in the present day as well as around the world, we’re interested in investigating the relationship between the environment and social systems.”

The agricultural terraces are believed to be around a thousand years old, built during the Medieval Climactic Anomaly. For more than 100 years during this period, South America saw cooler temperatures and increased droughts.

That timeframe — around 1100 CE—also saw the collapse of the Tiwanaku and Wari states in Peru, which preceded the expansion of the Inca Empire around 1450 CE. Known as the Auca Runa, or period of war and warriors in Peru, the years between 1100 and 1450 CE saw both climate crises and social chaos.

“I’m interested in seeing how they reformulated their agricultural systems during this time period to account for both climate change as well as social vulnerability because we know there was war,” Langlie said. “We don’t know how the herders and the farmers interacted, if they traded or if they kept separate from each other.”

In the Colca region, agriculture depends on elevation: At the valley bottom, farmers can grow tropical fruit trees, which gives way to maize further up, and then potatoes and quinoa. Llamas and alpacas feed at the hilltops, where only grasses grow.

Farmers and herders

The researchers are excavating a hillfort in the pastoral zone above the ancient terraces and some of the terraces themselves; during their project, they will use drones to survey the area. Langlie’s previous work in the Lake Titicaca basin shows that many Peruvian farming terraces date to a chaotic period of warfare and climate change, which may seem counterintuitive when you consider the difficulties of large-scale land transformation.

The researchers will head to the valley in the summer — winter in the Andes, which means their excavations won’t jeopardize any crops. Farmers still use the platforms, although some were destroyed by a landslide in 2020 that impacted the livelihoods of about 10,000 families in the region — a stark reminder of the realities of climate change.

One common assumption is that drought or warfare would prompt stationary farmers to abandon their failing fields; herders, by nature, are mobile and can move once food sources wane. However, it turns out that alpacas and llamas are highly susceptible to cold, making them vulnerable in times of extremity. They also have one offspring at a time after a long gestation period, unlike, for example, pigs.

“If you lose your herd, it will take a long time to reconstitute it,” Langlie explained.

Andean plant-based agriculture, however, is more resilient. There are more than 4,000 varieties of potatoes and dozens of quinoa varieties adapted to the varying climates of the Andes, including some that are drought- and cold-tolerant. Even today, Andean farmers will plant up to 10 different varieties of potatoes, which offsets the vulnerabilities of any one type.

The project is in partnership with Casa Cultural de Colca, a community organization in that region of Peru. The group runs a museum and will create displays about the research, with an eye toward the effects of climate change.

“We’ll be working with that community to understand how this ancient landscape worked in the past, and how these terraces are still facilitating agriculture today. They’re an important part of the livelihoods of the families that live there,” Langlie said. “We’re working with farmers not only to better understand the ancient landscape but to help them prepare for climate change in the future.”