In her new book, Megan Kassabaum of the School of Arts & Sciences challenges the field of archaeology to take a forward-looking approach rather than one that looks backward. Credit: University of Pennsylvania

Archaeologists often spend a career studying a single site, region, or time period, building on the field's previous research and interpretations. But some, like Penn's Megan Kassabaum, take a wider view that spans both time and geography by focusing on understanding widespread practices. Since arriving at Penn, Kassabaum has focused on tracking the long history of Native American platform mounds in the eastern United States.

The most common narrative is that these flat-topped mounds emerged about 1,000 years ago, at the same time as social hierarchy and corn agriculture. That conclusion worked because many excavated platform mounds dated to that particular time, and their sites tended to reveal a significant volume of "cool, fancy things," that have long attracted the attention of American archaeologists. Beyond that, it's easy to overlay the agriculture-based hierarchical society that has dominated the recent past onto deeper history, even if doing so doesn't quite fit.

In her new book, "A History of Platform Mound Ceremonialism: Finding Meaning in Elevated Ground," Kassabaum conceives of a new analytical approach, one that's forward-facing rather than backward-looking. That leads her to reach a different conclusion about platform mounds.

"For my dissertation project, I excavated platform mounds at one site that didn't have evidence of chiefs and didn't have evidence of corn," says Kassabaum, an assistant professor of anthropology and assistant curator for North America at the Penn Museum. She began to wonder, was her site an exception or was the common narrative inaccurate?

Analyzing work other archaeologists had conducted at nearly 150 other sites, Kassabaum found more exceptions than cases that actually proved the rule. "This narrative that we've constructed in our heads actually isn't supported by the evidence," she says, a notion that formed the basis of her book. In a conversation with Penn Today, Kassabaum offers four takeaways she hopes readers will glean.

The history of American archaeology led to current interpretations of platform mounds

"Archaeologists have always interpreted platform mounds as different from burial mounds or other types of mounds," she says. "The reason is that, in the later periods, they are clearly associated with powerful chiefs, building houses on top of them and overseeing large, permanent settlements that relied on corn agriculture."

A shift toward this mound type had always been considered pivotal, shaping how researchers today most often understand these flat-topped mounds. But "an examination of that history can allow us to question some of those long-standing assumptions," she says.

Platform mounds have a much longer history than is regularly recognized

That 1,000-year marker is just a blip in the story of these archaeological features, says Kassabaum, who argues that the practice actually dates back 7,500 years.

"They're not always the dominant form of earthen architecture," she says. "It's not that they were the only things being built—it would be impossible to ignore them if that were the case—but they were present from the earliest iterations of -building in North America, and they continue to be present all the way up to 1,000 years ago, that moment everyone focuses on, when they become really prevalent. Moreover, they actually are still being built and used by Native American communities today."

Archaeological thinking should shift from working backward to looking forward

"When archaeologists study long-term histories, we often work backward from the most recent examples. That's because they're the best understood," Kassabaum says. The documentation tends to be more thorough, and as sites get further away from present day it becomes harder to apply contemporary notions to them. "I understand that tendency," she says. "I've done that my whole career, too."

But Kassabaum now sees a fundamental flaw in that logic: It doesn't align with how the history was experienced by the people actually living it. As an example, she points to people living in 700 AD. "There's no way they could know what platform mounds would mean in 1000 AD, 300 years into the future. However, they absolutely would have had knowledge about what the mounds meant to the generation before them and potentially further back."

She proposes flipping archaeological interpretation on its head, no longer projecting backward but instead interpreting through what the inhabitants of that moment could have possibly known. "My hope is that we can rely less on those late moments in which we have great, high-resolution data and instead, acknowledge that even if it's a low-resolution, data-poor view, it's still the one we should focus on."

When applied to platform mounds, the new approach changes the narrative

Repeatedly, early examples of these sites emphasized aspects like communal feasting, groups coming together from widely dispersed areas, large-scale ritual—not a small number of elite people gathering. "That latter function seems to develop really late in the history of platform mounds," Kassabaum says.

For 6,500 years, the mounds meant something very different than they did 1,000 years ago, a moment that itself actually appears to be the outlier. As evidence, Kassabaum points to both the earlier archaeological examples and to the modern use of platform mounds, still in existence today. "They represent social solidarity, identity construction, and group cohesion," she says. "No one is talking about them as symbols of social hierarchy and differentiation."

In other words, that period that has been so influential in the history of archaeological thought is a comparatively brief moment of variation within a long and fairly consistent . "When you take a forward-looking approach," she says, "it fundamentally changes our understanding of the meaning of these mounds through time."