Hundreds of ancient mounds are scattered all over Louisiana. The mounds hold clues—in the forms of artifacts like projectile points, pottery, axes, grinding stones, fired earth objects, and more—about the prehistoric cultures who lived there thousands of years ago. I have distinct memories from childhood of visiting many of these mounds, including those at the famous Poverty Point World Heritage Site (which is about 3,400 years old), as well as those on the campus of Louisiana State University. New research on the LSU mounds—which have been listed on the National Register for Historic Places since 1999—has determined that they are the oldest known man-made structures in the Americas. The Advocate explains:
According to a study led by LSU Department of Geology & Geophysics Professor Emeritus Brooks Ellwood, radiocarbon dating suggests that construction of the first mound began as early as 11,000 years ago by ancient Indigenous people.
The two grassy mounds, located along Dalrymple Drive, now stand about 20 feet tall and are two of the more than 800 similar man-made mounds across Louisiana, most of which have been destroyed by time.
"There's nothing known that is man-made and this old still in existence today in North America, except the mounds," said Ellwood, who led the study recently published in the American Journal of Science by Yale University.
The new date on the mounds is not universally accepted, however. Chris Rodning, an anthropologist from Tulane University, expressed doubts about the accuracy of the new research. According to The Advocate, however, Professor Ellwood isn't bothered by the doubt:
He doesn't consider it an insult. "Everybody has their own belief and that's reasonable, but we've spent 20 years working on these mounds, and this is not a trivial amount of time that we're talking about," he said. "We've used a number of different approaches."
If Ellwood's radiocarbon dating is correct, though, that's pretty exciting news. And if not, the LSU mounds—and the others that can be found all across the state of Louisiana—are still pretty cool. If you're ever nearby, you should check them out!