Last September, two kayakers were out in the Minnesota River near the city of Sacred Heart, nearly 110 miles west of Minneapolis, when an odd-looking brown object sticking out of the riverbank caught their attention.

The unidentified pair then decided to alert the Renville County Sheriff’s Office after realizing it was likely a bone.

Sheriff Scott Hable initially suspected that the discovered bone fragment might belong to a missing person from the area, so he sent it to a medical examiner and then to an FBI forensic anthropologist in hopes of identifying the deceased.

However, on May 17, the anthropologist made a surprising discovery through carbon dating. The bone had come from a skull, but it was most likely from a young man who lived between 5500 and 6000 B.C.

“I don’t think anybody was anticipating the news to come,” said Sheriff Hable.

According to the forensic anthropologist, a hollow in the man’s skull indicated that he had previously suffered a serious head wound.

In photos, the edges of the wound appear smooth and rounded on the skull, indicating that it had healed and was not the cause of death, according to Kathleen Blue, an anthropology professor at Minnesota State University.

Research by the Archaeology Laboratory at Augustana University in South Dakota estimated the young man traveled through areas of what is now Minnesota during the Archaic period in North America, a time before sustainable farming.

The Renville County Sheriff’s Office issued a news release featuring images of the artifact on Facebook on Wednesday. However, Sheriff Hable said his office was contacted by several Native American groups in the state, including the Minnesota Indian Affairs Council, who warned that releasing photos of the skull was “very offensive to the Native American culture.”

Hable said the post was removed that afternoon, saying, “Because there’s a chance that the bones belong to somebody with Native American heritage, we’re just going to honor their request.”