Polycephaly

Polycephaly is the condition of having more than one head. The term is derived from the Greek stems poly (Greek: "πολύ") meaning "many" and kephalē (Greek: "κεφαλή") meaning "head". A polycephalic organism may be thought of as one being with a supernumerary body part, or as two or more beings with a shared body.
Two-headed animals (called bicephalic or dicephalic) and three-headed (tricephalic) animals are the only type of multi-headed creatures seen in the real world, and form by the same process as conjoined twins from monozygotic twin embryos.
In humans, there are two forms of twinning that can lead to two heads being supported by a single torso. In dicephalus parapagus dipus, the two heads are side by side. In craniopagus parasiticus, the two heads are joined directly to each other, but only one head has a functional torso. Survival to adulthood is rare, but does occur in some forms of dicephalus parapagus dipus.
There are many occurrences of multi-headed animals in mythology. In heraldry and vexillology, the double-headed eagle is a common symbol, though no such animal is known to have ever existed.
Two-headed people and animals, though rare, have long been known to exist and documented.
In humans, as in other animals, partial twinning can result in formation of two heads supported by a single torso. Two ways this can happen are dicephalus parapagus, where there are two heads side by side, and craniopagus parasiticus, where the heads are joined directly.
In dicephalus parapagus dipus, the two heads are side by side, on a torso with two legs, with varying levels of twinning of organs and structures within the torso. The shared body may have four arms altogether, or three arms, or two arms only. There are Greek-based medical terms for the variations, e.g. dibrachius means two-armed and tribrachius means three-armed. Both heads may contain a fully formed brain, or one may be anencephalic. If carried to term, dicephalus parapagus twins are usually stillborn, or die soon after birth. Survival to adulthood does however occasionally occur in cases where the twins are born with three to four arms. Chances of survival are improved if two complete hearts are present. Separation surgery is contraindicated, except in cases where one of the twins is clearly dying.
Giacomo and Giovanni Battista Tocci (born between 1875 and 1877), were dicephalus parapagus dipus twins who survived to adulthood. Each had his own pair of arms. They learned to speak several languages, but never learned to walk. Abigail and Brittany Hensel, born in 1990, are another instance of dicephalus parapagus dipus twins who grew up. They were born with two functional arms, plus a vestigial third arm, which was surgically removed. Each twin has her own complete head, heart and spine, and controls one arm and one leg. They developed good motor skills, and completed courses at school and university.
Craniopagus parasiticus is an extremely rare condition in which the two heads are joined directly together, and one twin (known as the autosite) has a functioning torso, while the other (known as the parasite) has only a vestigial torso. The parasite is supported by blood supplied from the autosite head. This threatens the life of the autosite by placing an additional burden on the autosite's vital organs. Operations to separate the two heads have been performed in the hope of saving the autosite.
Polycephalic animals often make local news headlines when found. The most commonly observed two-headed animals are turtles and snakes. Other species with known two-headed occurrences include cattle, sheep, pigs, cats, dogs, and fish. In 1894, a two-headed partridge was reported in Boston, Massachusetts. It was notable as a dicephalic animal for surviving into adulthood with two perfect heads. Scientists have published in modern journals about dissecting such animals since at least the 1930s. A 1929 paper studied the anatomy of a two-headed kitten.
Polycephalic animals, due to their rarity, are a subject of novelty. "We", a two-headed albino rat snake born in captivity in 2000 with both female and male genitalia, was scheduled to be auctioned on eBay with an expected price tag of $150,000 (£87,000), though their policy of not trading in live animals prevented the sale. On October 31, 2006, the World Aquarium announced that "We" was adopted by Nutra Pharma Corporation, a biotechnology company developing treatments using modified cobra venom and cobratoxin. "We" died of natural causes at age seven in June 2007, not long after being acquired by Nutra Pharma.
Two-headed farm animals sometimes travel with animal side shows to county fairs. Most notably, The Venice Beach Freakshow supposedly houses the largest collection of two-headed specimens in the world, including over 20 two-headed animals that are alive. Many museums of natural history contain preserved two-headed animals. The Museum of Lausanne in Lausanne, Switzerland, and the Ripley's Believe It or Not! museum in Gatlinburg, Tennessee, have collections of preserved two-headed animals. A very well preserved 2-headed lamb is on display in Llanidloes museum in Wales. A live two-headed tortoise named Janus can be seen at the Natural History Museum in Geneva, Switzerland.
In cases where multiple heads are fully developed and non-parasitic, they share control of the organs and limbs, though the specific structure of the connections varies. Animals often move in a disoriented and dizzy fashion, with the brains "arguing" with each other; some animals simply zig-zag without getting anywhere. Snake heads may attack and even attempt to swallow each other. Thus, polycephalic animals survive poorly in the wild compared to normal monocephalic animals.
Most two-headed snakes only live for a few months, though some have been reported to live a full life and even reproduced, with the offspring born normal. A two-headed black rat snake with separate throats and stomachs survived for 20 years. There is some speculation that the inbreeding of snakes in captivity increases the chances of a two-headed birth.
It is difficult to draw the line between what is considered "one animal with two heads" or "two animals that share a body".
Abigail and Brittany Hensel, born in 1990, were given two distinct names at birth. They identify as two people, and are recognised as two people legally and socially. On the other hand, Syafitri, born 2006 in Indonesia, were given one name by their parents because they only had one heart. In early Germany, conjoined twins that could not be separated were legally considered one person. Millie and Christine McKoy were often referred to in the singular, including by themselves, with the name "Millie-Christine", as well as plural.
In Peter Mogila’s 17-century Catechism, the following instructions are given for baptism of polycephalic infants: should there be distinct heads and distinct chests, this means there are separate people each of whom must be baptised normally; if the heads and chests are not completely distinct from each other, however, one person must be baptised normally but baptism of the other(s) should be preluded by the formula "if not already baptised".
With other animals, polycephaly is usually described as "one animal with two heads". One of the heads, especially in three-headed animals, may be poorly developed and malformed, and not "participate" much.
Where twinning of the head itself is only partial, it can result in the condition known as diprosopus—one head with two faces.
The February 22, 2007, issue of the journal Biology Letters detailed the discovery of a 122 million-year-old fossil of a two-headed Hyphalosaurus lingyuanensis, marking the earliest known occurrence of axial bifurcation.
Craniopagus parasiticus is a condition in which a parasitic twin head with an undeveloped or underdeveloped body is attached to the head of a developed twin. Only four cases have been documented by modern medicine to have survived birth:
There have been numerous reports of two-faced cats; most die soon after birth. Reports of two-headed kittens are common, relative to other animals, because of their status as household pets. Recent two-headed kittens include:
Polycephalic cats in museums include:
A full body taxidermy of a two-headed calf is on display at the Garth and Jerri Frehner Museum of Natural History on the Southern Utah University campus in Cedar City, Utah. "The Dancing Calves" were born by natural delivery with considerable assistance from S. T. Nelson of Cedar City, Utah on Mother's Day, May 8, 1949, to a crossbred cow owned by Willard Lund of Paragonah, Utah. The "Father Bull" is unknown but must have been an outstanding Hereford. The double calf was alive and healthy but died during birth. This calf, or calves, joined from the beginning of the neck as far as the belly, with two complete, almost perfect body frames, had but one system of vital organs. Each of the two normal heads had a food channel to one stomach and a breathing channel, or windpipe, to the one set of lungs. The two briskets, or breasts, shared on each side by these calves, contained the one set of lungs on one side and the one heart on the other side. Branching off from the one stomach and digestive system were two channels of elimination. The calf weighed approximately 85 pounds (39 kg) at birth. The over-all measurements as it stands mounted are: 42.5 inches (1,080 mm) high, 20 inches (510 mm) from tail to tail, and 18 inches (460 mm) from side to side including the front legs. The "Mother Cow" lived and was sold as a "fat cow" in July 1949. This calf was stuffed by C. J. Sanders, taxidermist, 2631 South State Street, Salt Lake City 5, Utah, who stated that it is the most unusual monstrosity he has ever worked with. Dr. A. C. Johnson, of Cedar City, Utah, stated that this was the best specimen of monstrosity in animal life that he has ever seen or heard of in his 47 years of practice as a veterinarian. "The Dancing Calves" were owned by West and Gail Seegmiller who displayed them for many years at their Desert Pearl Cafe (no longer in existence), in Cedar City, Utah. Dr. A. C. Johnson, Dr. T. Donald Bell, William H. Lund, Dr. R. G. Williams, Dr. J. S. Prestwich, Dr. A. L. Graff, S. T. Nelson, and James Hoyle Jr. all signed as witnesses that they saw the calf in the flesh soon after birth and knew it to be authentic. The calves and original document were donated to the Garth and Jerri Frehner Museum of Natural History on the Southern Utah University campus in Cedar City, Utah, where they are now on display.
Most polycephalic snakes do not live long, but some captive individuals do.
Two-headed turtles and tortoises are rare but not unknown. Recent discoveries include:
In 2006, a paper published by the British Royal Society reported the discovery of a fossil of a two-headed embryo or neonate of the long-necked choristodere reptile Hyphalosaurus, which was the first record of fossilized polycephaly.
Greek mythology contains a number of multi-headed creatures. Typhon, a vast grisly monster with many snake heads, is often described as having several offspring with Echidna, a creature with the lower body of a serpent but the upper body of a beautiful woman. Their offspring, by one source or another, account for many of the major monsters of Greek mythos, including:
Other multi-headed creatures in Greek mythology include:
Zahhak, an evil figure in Iranian mythology - also evident in ancient Iranian folklore as Aži Dahāka (Azh dahak) - is the most significant and long-lasting of the ažis of the Avesta, the earliest religious texts of Zoroastrianism. He is described as a monster with three mouths, six eyes, and three heads (presumably meaning three heads with one mouth and two eyes each), cunning, strong and demonic. But in other respects Aži Dahāka has human qualities, and is never a mere animal.
Hindu deities are often depicted with multiple arms or heads.
Though usually depicted with one head, some deities like Ganesha (in Heramba form) and Shiva (Sadashiva) have aspects where they are depicted with multiple heads; five in this case. The Vishvarupa form of Vishnu is described as having infinite heads.
Besides deities, demons (asura and rakshasa) may be depicted with multiple heads. The demon-king Ravana is depicted and described as having ten heads, although sometimes he is shown with only nine heads because he has sacrificed a head to convince Shiva. Trishira, his son, is depicted with three heads.
Animal races in Hindu mythology like Nāgas (serpents) may have multiple heads. The Naga Shesha is depicted with five or seven hoods, but said to have infinite hoods. Uchchaihshravas is a celestial seven-headed horse. The divine white elephant Airavata is depicted with multiple heads, trunks and tusks.
The Talmud (Brachot 61a) says that originally Adam was created as a single body with two faces (which were then separated into two bodies - male (Adam) & female (Eve)).
The Zohar (introduction 1:9B / p. 9B) speaks of descendants of Cain with 2 heads.
The Talmud (Menachot 37a) records an incident in which Phlimo asked Judah the Prince which head a two headed person should put on Tefillin. Judah was initially dismissive, but then another man came in saying that his wife had just given birth to a two headed baby, and asked a (different) halachic question.