These days, a black chain-link fence some six feet tall surrounds a pair of gently sloping grass-covered mounds on the main campus of Louisiana State University in Baton Rouge. A newly installed placard zip-tied to the fence provides curious passersby with some context:
“The mounds are the oldest known human-made earthworks in the Americas. Recent studies now estimate that the mounds could be up to 11,300 years old, updating previous studies that estimated they were built 6,000 years ago.”
For visitors tempted to fact check that superlative, a quick search on Google seems to verify the claim. What’s known as a featured snippet appears at the top of the page, summarizing results from a June 2022 study in the American Journal of Science, followed by links dominated by news stories about the paper’s findings.
But ask an archaeologist, and they’ll probably tell you the answer is not so simple.
For months, the straightforward way in which Google has answered this query has deepened a rift in an academic field that already had an uneasy relationship with definitive claims. For professional archaeologists, the burden of proof for a major discovery is staggeringly high, in part because of the difficulty in interpreting artifacts that have been weathered, broken apart and scattered over the centuries.
A Google spokesperson explained that snippets pull information from high-quality sources, and in the case of the LSU mounds, the featured snippet points to a news article from an established source that highlights the scientific study. What’s missing from the snippet is that several archaeologists have questioned the study’s interpretations.
The ongoing, if mostly unseen, debate is the latest chapter in the story of North America’s earthen mounds, which offers a cautionary tale about the historical challenges of walking back established narratives. It’s also a case study of the process by which scientific discoveries — confirmed or not — become popularly accepted as fact in the modern era of rapid communication dominated by search algorithms and a superabundance of information, not all of which is reliable and complete.
An enduring mystery
Around the same time that the ink was drying on the U.S. Constitution, settlers moving west into the Ohio and Mississippi valleys were encountering curious aspects of the landscape: mounds, platforms and embankments that had been clearly sculpted by human hands. Although such structures had been documented centuries before — notably by Hernando de Soto in the mid-1500s — reports of enormous earthen works on the western frontier captivated the public imagination.
