The remains are the earliest evidence of ritualized blood sacrifice and mutilation of children that has so far been seen in the South American Andes, according to study leader Haagen Klaus.

Seeds of a paralytic and hallucinogenic plant called Nectandra, which also prevents blood clotting, were found with the skeletons, suggesting the children were drugged before their throats were slit and their chests cut open.

During the sacrifices, sharp bronze knives were used to hack the children to death. One skeleton had more than 25 cut marks on it. A few had their hands and legs bound with rope.

"It is so beyond what is necessary to kill a person. It really gives you the chills," Klaus, an anthropologist