The southernmost LSU Campus Mound is now considered the oldest known man-made structure in North America, research conducted by LSU geologist Brooks Ellwood suggests.

Ellwood determined that the mounds were 11,300 and 8,200 years old, respectively, using radiocarbon dating. The previous ages weren’t certain but they had been known to be over 8,000 years old. 

“The oldest dates we have are from the B mound and it’s approximately 11,300. Now that number is from the bottom sample that we analyzed,” Ellwood said. “We could have gone deeper and measured another sample and the probability is it would have been older.”

The carbon dating was done at Beta Analytic, a radiocarbon dating lab in Miami, Ellwood said. 

Ellwood said both mounds contain osteons, microscopic bone particles, belonging to a mammal species of some kind. He explained that this organism was being cremated on the mounds, implying that it could have been human. Native American groups won’t allow them to do DNA testing because the remains are sacred to them, Ellwood said.

“They won’t allow us to do DNA, so we don’t know if these mammal bones were animal or human,” Ellwood said.

Ellwood said Mound B, the southernmost mound, was the first built, but it’s believed that around 8,200 years ago there was an asteroid strike in Greenland, which destabilized the climate. This caused the people who built the mounds to leave the area, he said. When they returned, they built the base of Mound A and then rebuilt Mound B taller.

The mounds were built in alignment with the star Arcturus, Ellwood said. The Monte Sano mounds, built closer to the Mississippi river, were also in alignment with the star but were later bulldozed, he added. The star has since moved in the night sky, so the mounds no longer align with it.

Despite being built in alignment with Arcturus and containing mammalian remains, the exact purpose of the mounds is unclear.

“Whether it was religious…we don’t know because we can’t talk to them,” Ellwood said. “Although they kind of talk to us in a way.”

The people who built the mounds were hunter-gatherers, according to the LSU Campus Mounds website.

The Committee to Preserve the Indian Mounds, a university committee, has been working to establish a permanent barricade around the mounds with a viewing platform and signage detailing their history. 

Sibel Bargu Ates, the committee’s chair, said the plans also involve re-routing the roads around the Mounds to reduce traffic. She said the planned construction will cost around $4 to 5 million. The construction will begin sometime in the next few years. 

“I think it doesn’t matter how much you protect, if you don’t educate it’s just meaningless to me,” said Ates, who also serves as associate dean at the College of the Coast and Environment. ”So I really wanted the education component to go right next to the funding. It’s a cycle. The more we educate people I think the more funding we’re going to get because people will understand the value and will want to support that.”

LSU has agreed that there is a responsibility to fund this project, Ates said. Fundraising is expected to begin soon. 

The committee has established the LSU Campus Mounds website to provide information about the Mounds’ history and the work being done to preserve them. The website is expected to have a means to donate to the project.

Psychology senior Sahara Hansen, president of the Native American Student Association, believes the fencing around the mounds needs updated placards providing information on their significance. 

“LSU needs to take the first steps when it comes to funding the preservation and education plan for the students,” Hansen said. “LSU is currently housing the oldest man-made structure to date, and we should all do our part to properly honor and preserve them, especially the university itself.”

Leigh-Anne Thompson, a representative of the Coushatta tribe on the committee, said they are working on getting fundraising groups to raise money for the mounds. 

The committee is also working to get educational groups to spread information about the mounds, Thompson said. No trespassing signs are expected to be placed around the temporary fencing for the mounds. 

People need to understand how significant the mounds are and why it’s not okay to go on them, Thompson said.

“I think people just have to understand that times are changing,” she said. ”More information is coming out about the mounds about how historic they are and how old they are and what they potentially could have been used for so it could be really disrespectful if it was used for maybe burial grounds.”