During a recent study conducted in the central Petén region of Guatemala, researchers from Southern Illinois University examined 108 arrowheads collected from five Mayan archaeological sites within the past 20 years. Using a process called crossover immunoelectrophoresis (CIEP) analysis, they discovered blood on 25 of the arrowheads—and on two, the blood is human.

The process has been used to detect blood in the past, including at the site of an ambush in Kosovo, but this is the first time it has been used on ancient Mayan weaponry. Using the technology and their knowledge of Mayan beliefs and traditions, the team has concluded in a report published in the Journal of Archaeological Science that a spot near a Mayan temple in Zacpetén was once used for a bloodletting ceremony to feed the gods. The arrowheads date from the 15th to the 18th centuries. 

According to LiveScience, when the blood was tested with serums containing antibodies from different animal species, the results showed that human blood was present on two of the artifacts. One of the arrowheads was found in a house, with damage to the tip, which led the researchers to believe that it struck someone who survived and was carried inside, or that the arrow was reused. 

The other arrowhead is the object believed to have been used in the ceremony, which took place roughly 500 years ago. “During the ceremony someone was cut open—possibly through the earlobes, tongue or genitals—with an arrowhead made of obsidian (a volcanic glass), and their blood was spilled,” according to LiveScience. Prudence Rice, coauthor of the study, explained that the Maya believed that humans had a life force that provided nourishment to the gods through bloodletting. “We know Mayas also participated in bloodletting as a part of birth or coming-of-age ceremonies,” said her co-author, Nathan Meissner. He added that the ceremonial cutting may have been voluntary, and that the cut person is likely to have survived.