twoheaded

Twoheaded is an adjective describing organisms that possess two heads. In science, two-headed configurations are rare congenital anomalies. When two heads share a single body, the condition is usually described as dicephaly or bicephaly. If faces are duplicated on a single head, the term diprosopus (craniofacial duplication) is employed. The term twoheaded is also used more generally to describe mythological, fictional, or artificially created entities with two heads.

Occurrence and prognosis: In humans and other animals, two-headedness arises from abnormal development of the early embryo, a form of conjoined twinning or craniofacial duplication. Most cases are not viable; those that survive often face complications including neurological and circulatory challenges, and many do not survive infancy or early life.

Examples in nature and culture: Notable mythological examples include Orthrus, the two-headed dog in Greek myth; Amphisbaena, a serpent with heads at both ends. In art, literature, and film, twoheaded figures are used to symbolize duality or otherness. In zoology and veterinary literature, rare documented cases exist among snakes, turtles, birds, and mammals, often reported as isolated individuals.

Related terms include conjoined twins, diprosopus, and bicephaly.