Ancient pyramids, cliff dwellings, tools and artwork — and the sites where they’re found — are the bread and butter of traditional archaeology.

But Clark Erickson, associate professor of anthropology and a curator at the University Museum, is changing the stuff of archaeology by paying close attention to the spaces between sites, where ancient people shaped the landscape itself.

Erickson’s latest research deals with massive earthwork fish traps built hundreds of years ago on the savannas of northeastern Bolivia by the indigenous Baure people.

Prior to the Spanish colonists’ arrival in the 1600s, the Baure built causeways to aid navigation between the raised forest islands where their villages were. The causeways, which amounted to a sort of interstate highway system, consisted of raised walkways, which could stay dry during the seasonal flooding of the savannas, and canals for small boats to carry goods between villages.

Last summer, as Erickson flew over the Bolivian savannas taking photographs of these earthworks, he noticed structures that didn’t fit in with the perfectly straight causeways. These other structures were zigzag-shaped, changing direction every 30 to 40 meters.

Upon examining the zigzags more closely, he discovered small openings in the structures’ low earthen walls. These funnel-shaped openings led him to believe that the structures are fish weirs, built to guide fish from the flooded plains into smaller channels where fish could be easily caught.

“Almost every society that eats fish has some form of weir,” said Erickson. “But they’re usually ephemeral, made of putting sticks in a riverbed, things like that. I’d never seen anything on this scale — the complex possibly covers 500 square kilometers — or anything this permanent.”

This summer, when Erickson returns to Bolivia, he’ll work with local Baure — descendents of the original weir-builders — to reconstruct portions of the weirs and study how they may have worked hundreds of years ago.

Erickson said his research has implications for conservation in the Amazon and elsewhere. “The old model of conservation was you take what you think is a pristine, untouched forest, and you put a fence around it,” he said. “The myth is that native peoples were these ecologically noble savages who tiptoed through the forest and didn’t disturb it. But through archaeology, we can show that humans are always changing their environment.”

This may take less striking forms than massive fish weirs, he added. Other common indigenous practices like periodically setting fire to forests and savannas or selectively cultivating certain plants also alter the environment.

So, said Erickson, if the land we think of as “nature” is itself a result of hundreds if not thousands of years of human impact on the environment, then the ecological question — Should human activity be adjusted for the environment’s sake? — becomes one of scale and degree. The Baure and other native peoples created a “mosaic of disturbance” in the Amazon, “managing it in a very complex way, which is very different from the clear-cutting that occurs along the roads in the Amazon. It’s very important to point out those kinds of differences.”