Burying the dead facedown in ancient times didn't mean RIP, according to new research that says the practice was both deliberate and widespread.

Experts have assumed such burials were either unusual or accidental.

But the first global study on the facedown burials suggests that it was a custom used across societies to disrespect or humiliate the dead.

Lead study author Caroline Arcini of Sweden's National Heritage Board detected a common thread in the burials she studied: "That society sanctioned this apparently negative treatment of the dead," she said.