lycanthropy

The Greek physician Marcellus of Sida described the condition in the second century CE, naming it for the myth of Lycaon, the Arcadian king whom Zeus punished by turning him into a wolf. The name combined lykos, wolf, with anthropos, human being. Later Byzantine physicians preserved the term in medical texts as a recognized psychiatric condition, distinct from ordinary madness.

Medieval European physicians inherited the term through Latin translations of Greek medical texts and applied it to patients who wandered cemeteries at night howling and avoided human contact. The Church complicated the picture by treating some cases as demonic possession rather than illness. The physician and the priest disagreed about what stood before them, which sent treatment in two very different directions.

Robert Burton included lycanthropy in The Anatomy of Melancholy in 1621 as a sub-type of melancholia, locating its cause in the humoral system's excess of black bile. This framing moved the condition from the supernatural toward the natural, even as folk belief in werewolves persisted across rural Europe. The term appears in English writing from at least 1584, in Reginald Scot's The Discoverie of Witchcraft.

Modern psychiatry has documented clinical lycanthropy as a rare delusional syndrome in which patients genuinely believe they are transforming into animals. The wolf remains the most common focus, though cases involving cats, dogs, and tigers have been recorded. The DSM does not list it as a separate category; it appears as a symptom within broader psychotic disorders.