A cache of human bones confirms historical accounts that the ancient Celts decapitated their enemies and embalmed the heads for public display.

Greek historians Diodorus and Strabo both wrote that Celtic warriors preserved the heads of their foes with cedar oil. To test this claim, Réjane Roure at the Paul Valéry University of Montpellier in France and her colleagues examined bits of skull excavated at Le Cailar, a fortified Celtic settlement in southern France. The skull fragments, which dated to the third century BC, were found with metal weapons and other artefacts in a large display area inside the settlement’s walls.

Chemical analysis revealed signatures of resin and plant oils on the skull fragments, which bore cut marks suggesting that the brains had been removed. The embalming mixture had “anti-odour properties”, the authors write, and would have slowed bacterial decay of the tissue.