Shapeshifting is a common theme in mythology and folklore, as well as in science fiction and fantasy. In its broadest sense, it is when a being undergoes a transformation. Commonly the transformation is purposeful, and not a curse or spell. In some folklore once the shapeshifter transformed, it began to get harder and harder to change back to ones original form. Vampires and werewolves are somewhat similar. Vampires, in older pieces of mythology and folklore, were thought to be able to transform into a wolf or a bat^{[citation needed]}, thus giving the vampire bat its name^{[dubious – discuss]}. Most shapeshifters change into an animal, they were believed to only be able to change into an animal, or person that they had seen.

Shamanism

Ethnologist Ivar Lissner theorised that cave paintings of beings with human and non-human animal features were not physical representations of mythical shapeshifters, but were instead attempts to depict shamans in the process of acquiring the mental and spiritual attributes of various beasts.^[7] Religious historian Mircea Eliade has observed that beliefs regarding animal identity and transformation into animals are widespread.

 Transmigration of souls

Therianthropy is often confused with transmigration; but the essential feature of the were-animal is that it is the alternative form or the double of a living human being, while the soul-animal is the vehicle, temporary or permanent, of the spirit of a dead human being. Nevertheless, instances in legend of humans reincarnated as wolves are often classed with lycanthropy, as well as these instances being labeled werewolves in local folklore.

There is no line of demarcation, and this makes it probable that lycanthropy is connected with nagualism and the belief in familiar spirits, rather than with metempsychosis, as E. B. Tylor argued, or with totemism, as suggested by J. F. M'Lennan. Thus, these origins for lycanthropy mingle a belief in reincarnation, a belief in the sharing of souls between living humans and beasts and a belief in human ghosts appearing as non-human animals after death. A characteristic of metempsychosis is a blurring of the boundaries between the intangible and the corporeal, so that souls are often conceived of as solid, visible forms that need to eat and can do physical harm.^[9]

Animal ancestors

Stories of humans descending from animals are common explanations for tribal and clan origins. Sometimes the animals assumed human forms in order to ensure their descendants retained their human shapes; other times the origin story is of a human marrying a normal animal.

North American indigenous traditions particularly mingle the idea of bear ancestors and ursine shapeshifters, with bears often being able to shed their skins to assume human form, marrying human women in this guise. The offspring may be creatures with combined anatomy, they might be very beautiful children with uncanny strength, or they could be shapeshifters themselves.^[10]

P'an Hu is represented in various Chinese legends as a supernatural dog, a dog-headed man, or a canine shapeshifter that married an emperor's daughter and founded at least one race. When he is depicted as a shapeshifter, all of him can become human except for his head. The race(s) descended from P'an Hu were often characterized by Chinese writers as monsters who combined human and dog anatomy.^[11]

In Altaic mythology of the Turkic and Mongolian peoples, the wolf is a revered animal. The shamanic Turkic peoples even believed they were descendants of wolves in Turkic legends. The legend of Asena is an old Turkic myth that tells of how the Turkic people were created. In Northern China a small Turkic village was raided by Chinese soldiers, but one small baby was left behind. An old she-wolf with a sky-blue mane named Asena found the baby and nursed him, later giving birth to the half wolf, half human cubs who were the ancestors of the Turkic people. ^[12][13]

 Animal spirits

In North and Central America, and to some extent in West Africa, Australia and other parts of the world, every male acquires at puberty a tutelary spirit. In some Native American tribes the youth kills the animal of which he dreams in his initiation fast; its claw, skin or feathers are put into a little bag and become his "medicine" and must be carefully retained, for a "medicine" once lost can never be replaced. In West Africa this relation is said to be entered into by means of the blood bond, and it is so close that the death of the animal causes the man to die and vice versa. Elsewhere the possession of a tutelary spirit in animal form is the privilege of the magician. In Alaska the candidate for magical powers has to leave the abodes of men; the chief of the gods sends an otter to meet him, which he kills by saying "O" four times; he then cuts out its tongue and thereby secures the powers which he seeks.

The Malays believe that the office of pawang (priest) is only hereditary if the soul of the dead priest, in the form of a tiger, passes into the body of his son. While the familiar is often regarded as the alternative form of the magician, the nagual or bush-soul is commonly regarded as wholly distinct from the human being. Transitional beliefs, however, are found, especially in Africa, in which the power of transformation is attributed to the whole of the population of certain areas. The people of Banana are said to change themselves by magical means, composed of human embryos and other ingredients, but in their leopard form they may do no harm to mankind under pain of retaining forever the beast shape. In other cases the change is supposed to be made for the purposes of evil magic and human victims are not prohibited.

A further link is supplied by the Zulu belief that the magician's familiar is really a transformed human being; when he finds a dead body on which he can work his spells without fear of discovery, the wizard breathes a sort of life into it, which enables it to move and speak, it being thought that some dead wizard has taken possession of it. He then burns a hole in the head and through the aperture extracts the tongue. Further spells have the effect of changing the revivified body into the form of some animal, hyena, owl or wild cat, the latter being most in favour. This creature then becomes the wizard's servant and obeys him in all things; its chief use is, however, to inflict sickness and death upon persons who are disliked by its master.

In Melanesia there is a belief in the tamaniu or atai which is an animal counterpart to a person. It can be an eel, a shark, a lizard, or some other creature. This creature is corporeal, can understand human speech, and shares the same soul as its master, leading to legends which have many characteristics typical of shapeshifter tales, such as any death or injury affecting both forms at once.^[14]

 Hybrids

Therianthropy can also refer to artistic descriptions of characters that simultaneously share human and nonhuman animal traits, for example the animal-headed humanoid forms of gods depicted in Egyptian mythology (such as Ra, Sobek, Anubis, and others) as well as creatures like centaurs and mermaids.  

Shape-shifting

Some common forms of therianthropy have their own terminologies. Of these, lycanthropy, cynanthropy, and ailuranthropy are the best known.^[15] The term "cynanthropy" was applied in 1901 to Chinese myths about humans turning into dogs, dogs becoming people, and sexual relations between humans and canines.^[16]

 Lycanthropy

In folklore, mythology and anthropology, the most commonly known form of therianthropy is lycanthropy (from the Greek words lycos ("wolf") and anthropos ("human being")). Although the definition specifically describes a metamorphic change from human to canine form (as with a werewolf), the term is often used to refer to any human to nonhuman animal transformation.

Psychiatry

Among a sampled set of psychiatric patients, the belief of being part animal, or clinical lycanthropy, was generally associated with severe psychosis, but not always with any specific psychiatric diagnosis or neurological findings.^[17] Others regard clinical lycanthropy as a delusion in the sense of the self-identity disorder found in affective and schizophrenic disorders, or as a symptom of other psychiatric disorders.^[18].

 References in popular culture

 In fiction

A Practical Guide to Monsters, a Dungeons and Dragons themed book published under Wizards of the Coast's juvenile publishing imprint Mirrorstone Books, makes reference on page 33 to D&D's use of the term lycanthrope to refer to many different types of humanoid/animal shapeshifters. The text goes on to state that "A better term for this group would be 'therianthrope,' from the root therios (animal)."^[19]

Although the were-wolf is the best known animal transformation figure in popular culture, the plots of several novels in the fantasy and mythic fiction fields revolve around other kinds of therianthropic characters. Swim the Moon by Paul Brandon, set in contemporary Australia, explores Scottish selkie legends. The Antelope Wife by Louise Erdrich, set in modern-day Minnesota, draws on Ojibway myths of women who can shift between human and antelope shape. The Fox Woman by Kij Johnson, set in historic Japan, re-tells a kitsune legend in novel form. Coyote Blue by Christopher Moore is a contemporary comic novel about a Native American trickster who can shift between human and coyote forms. Hannah's Garden by Midori Snyder, set in the rural American midwest, draws on Anglo-Irish legends of shape-changing hares to tell a story about death, family dynamics, and the power of creativity. The Wood Wife by Terri Windling, set in Tucson, Arizona, and most of the novels of Charles de Lint, set in Canada, blend the shape-shifting legends of European folklore, the therianthropic lore of tricksters and shamans, and animal-human hybrid characters drawn from various Native American mythologies. Alice Hoffman draws on the folklore of therianthropy and lycanthropy in her contemporary novel Second Nature, although in this case the protagonist shiftshapes metaphorically rather than literally, having been raised by wolves in the wild.^[20][21] In J. R. R. Tolkien's The Hobbit, Beorn was a man who could assume the appearance of a great black bear.

 Subculture

The first widely-known internet use of the term developed among the Usenet group alt.horror.werewolves (ca. 1992).^[22] Some Usenet users began publicly asserting that they were part animal, generally in a spiritual sense. ^[23] Such people initially called themselves lycanthropes, but because that word specifically means wolf-people the term therianthropes became more popular. From these foundations, a subculture of individuals identifying as therianthropes has developed.^[24]. Some self-described therianthropes also consider themselves members of the Otherkin subculture.^[25]