VanValkenburgh explained that the GeoPACHA project is important because it does more than elucidate sweeping 16th-century changes in the Andean region. It also shows that, when archaeologists who study niche topics work together to collect multiple points of data, they can identify important historical shifts in climate and culture across the globe.

“Working at larger scales can help archaeologists generate more impactful research that addresses topics like the development of social inequality, the devastating legacies of colonialism and the responses of past societies to climate change,” VanValkenburgh said. “We need a deeper record of how humans have dealt with these sorts of challenges in the past. Archaeology is one of the rare fields that provides us with the kind of time depth we need to do that.”

Mapping history

GeoPACHA began in 2018, when VanValkenburgh and Wernke brought together a handful of researchers who aimed to answer specific archaeological questions using large-scale satellite mapping. One team, for example, was focused on mapping hilltop fortifications to answer questions about social conflict in the Andes between 1100 and 1400. Another hoped to identify sites associated with lomas — verdant, fog-shrouded oases dotted throughout an otherwise arid landscape — to identify patterns in where Indigenous people chose to settle. 

Working with high-resolution satellite imagery in GeoPACHA, the researchers used their specialized knowledge to find and tag certain landmarks, including hill forts and sheep corrals.

“It’s what we’d call ‘brute-force’ surveying,” VanValkenburgh said. “You take people who are trained to recognize archaeological sites, and you have them just click whenever they recognize something.”

After the mapping work came months of analysis, much of which is detailed in the new Antiquity publications. Some of the scholars’ analyses identified patterns that have yielded important new insights into how life changed in the Andes after Spanish colonization. 

Bethany Whitlock, a recent Brown Ph.D. graduate in anthropology, led one study analyzing the locations of roads and sheep corrals in Peru’s central highlands. Whitlock said she discovered that herding infrastructure tended to be “concentrated around important colonial and present-day settlements” — evidence, she believes, of the long-term impact of colonialism on pastoralism and settlement in the Andes. 

Giancarlo Marcone, a professor at Peru’s Universidad de Ingeniería y Tecnología, led another study analyzing lomas on Peru’s central coast. Marcone said there’s evidence that past settlers spent significant time in these pockets of dense vegetation, but their activity isn’t well documented because scientists can’t access the lomas’ remote locations on foot. With GeoPACHA, he said, it’s finally possible to begin studying how changes to culture and climate have transformed lomas.

“These research efforts are an urgent priority for understanding the long-term history of this part of Andean South America,” Marcone said.

GeoPACHA’s next phase

VanValkenburgh, Wernke and other colleagues’ archaeological mapping work doesn’t end here. Along with Vanderbilt Assistant Professor of Computer Science Yuankai Huo, the pair recently received a $348,190 grant from the National Endowment for the Humanities to broaden the project’s  scope, this time with the assistance of artificial intelligence. Using deep learning methods, the GeoPACHA team will be able to survey nearly all of the central Andean region. 

VanValkenburgh said the second phase of the project will pull in additional scholars from Peru, Chile, Bolivia and Ecuador, countries that include lands that were once part of the vast Inca Empire. Those scientists will evaluate the data collected by AI and enrich it with their own specialized knowledge.

“We’re taking those data that were painstakingly curated during the first phase of the project, and we’re using them to train deep learning models to identify sites en masse,” he said. “Using AI, we’ll be able to cover an area that’s 10 to 20 times larger than our initial research areas. The questions we can address with such a large data pool are pretty exciting.”

Data from the three-year project could beget years of analyses and new archaeological findings, VanValkenburgh said. Locating and dating every single ancient terrace ever built in the Andes, for example, could help archaeologists answer important questions about how climate change, population density and imperial expansion influenced Indigenous people’s decisions about where to settle and grow crops. 

Questions like those, he said, seemed impossible to answer back when he was excavating individual pits in one small valley. While the excavation of interesting individual items can be exciting for archaeologists and the general public, he said, so can large-scale, multi-country digital projects like GeoPACHA.

“There’s this myth that archaeology is about stuff: Lost city discovered! Ancient scrolls found!” VanValkenburgh said. “Individual discoveries do matter, but fundamentally, archaeology is about relationships — it’s about understanding how people interacted with each other, how different societies on different continents were similar and different, how the past connects with the present. That can happen when we venture beyond our individual sites and build our own relationships across institutions and borders.”