Two-Faced Animals: Diprosopus or Craniofacial Duplication
What Is a Janus Cat?
Janus cats have a face that is completely or partially duplicated. They are named after Janus, the Ancient Roman god who gave his name to the month of January. Janus had two faces, one looking forwards and one looking backwards. The technical name for the two-faced condition in real life is diprosopus or craniofacial duplication. It appears in other animals and in humans, but in North America it's probably best known for its existence in Frank and Louie. He was a ragdoll cat who lived successfully with the condition.
A Janus cat is one individual and has one head, one brain, one body, and one set of internal organs. The only part of the body that's always duplicated is the face. The amount of facial duplication varies. Sometimes structures close to the face are duplicated as well, including the esophagus—the tube that transports food from the throat to the stomach—and the front part of the cerebrum in the brain.
Frank and Louie died from cancer in 2014 at the age of fifteen. While his death is sad, examining his life is fascinating. Frank and Louie was a very significant example of a two-faced animal. He was significant because he lived a long and happy life despite his unusual features. Most animals with diprosopus die shortly after birth, but Frank and Louie defied the odds.
Frank and Louie, a Two-Faced or Janus Cat
Although a face is the means by which we recognize someone, the identity of a person or animal is really determined by their brain. Even when their face changes due to surgery, they are still the same individual. Similarly, the fact that an animal has two faces doesn't affect their identity, as long as they have only one brain.
Frank and Louie or Frankenlouie
Despite Frank and Louie's double name, he was one cat. After Frank and Louie was born in 1999, he was taken to a vet in Massachusetts as a one-day-old kitten. The plan was to euthanize him. It was thought that this was the kindest thing to do because there was no way that he could survive. Janus kittens typically live for only a few days.
A veterinary technician named Marty took pity on Frank and Louie. She took the kitten home with her, where he not only survived but eventually thrived. He did require surgery to correct some of his abnormalities, however. Frank and Louie was awarded a Guinness world record in 2012 for being the longest lived Janus cat.
Frank and Louie's Life
Frank and Louie's two faces had three eyes in total, although the middle one wasn't functional, two noses, one functional mouth, and one nonfunctional mouth that lacked a lower jaw. He had only one esophagus. Luckily, unlike the case in most Janus cats, his combination of abnormalities didn't interfere with his survival or his enjoyment of life (once corrective surgery had been performed). Based on his lifespan and his normal behaviour, he didn't appear to have any duplication of the front of his brain.
Frank and Louie was an outgoing cat who enjoyed playing games, being stroked, walking on a leash, and taking car rides. He seems to have had a similar personality to my two ragdolls. He was able to move with ease in the direction that he wanted, even though his two functional eyes were widely separated. When he wanted to see something in detail, however, he had to swivel his head so that each of his eyes could collect information. He fed through his functional mouth on his right face, which was connected to his esophagus.
Frank and Louie Sets a Guinness World Record
The development of two faces is due to errors during the embryonic development of the animal. The condition is a sad one for animal lovers, since the affected animal usually dies, but its biology is interesting. The inspiring story of Frank and Louie shows us that a short or unhappy life may not be inevitable for all animals with diprosopus.
Humans With Two Faces
Diprosopus occurs in other animals besides cats. It's a rare and curious condition, so it usually makes news headlines when it's discovered. As in cats, all or only part of the face may be duplicated.
Sadly, humans can experience cranofacial duplication as well, though the condition seems to be rarer in humans than in other animals. Babies with diprosopus are usually stillborn or die shortly after birth. At least one person is an exception, however. Tres Johnson of Missouri has partial craniofacial duplication and celebrated his thirteenth birthday in 2017. I haven't seen any more recent reports about him. I hope he's doing well.
Classification of Duplication Problems
In the amazing world of biology there are many possibilities. The classification of humans and animals with two faces can sometimes be confusing. Some categories are described below.
- Humans or animals with diprosopus or craniofacial duplication have one head, one brain, and two faces (or partially duplicated faces). They are one individual. An example of someone with a completely duplicated face was Lali Singh. She was born in India in 2008 and lived for two months.
- Conjoined twins have two heads, two brains, and two faces. They are two individuals, but their bodies are partially or completely fused. They may even have one body or share some of their internal organs. Although conjoined twins may die at a young age, some survive. Human conjoined twins can sometimes be separated surgically or live successfully while joined together. A current and inspirational example of the latter situation is the case of Abigail and Brittany Hensel in the United States.
- An intermediate condition is possible. A sad example occurred in 2014 with the birth of Faith Daisy Howie and Hope Alice Howie in Australia. Faith and Hope each had their own face and their own brain. However, their brains were located in a single skull and they had only one head. The girls also had only one body. They lived for nineteen days.
The term "diprosopus" means two-faced in Greek. Despite the name, an animal with diprosopus may not have complete facial duplication.
The Biological Cause of Diprosopus or Craniofacial Duplication
The details of how an individual animal develops diprosopus aren't known. It occurs due to a problem in embryonic development. The cause of complete facial duplication may be different from the cause of partial duplication.
It's strongly suspected that the cause of partial facial duplication is related to a protein known as "sonic hedgehog". The production of sonic hedgehog is directed by a gene of the same name. The first hedgehog proteins were found in fruit fry larvae that had a spiky appearance. The spikes reminded researchers of a hedgehog's spines. When similar proteins were found in humans, researchers named them after a character called Sonic the Hedgehog in Sega Genesis video games. One of the research team had a child who liked this character.
The Sonic Hedgehog Gene and Protein
Researchers are discovering that sonic hedgehog is involved in many different activities during embryonic development. The protein and its gene play a role in the patterning of the face during embryonic development. Very rarely, too much sonic hedgehog is made, which may lead to excessive duplication of structures. The protein also affects the development of the front part of the brain and is involved in the development of the heart as well.
One example of sonic hedgehog's function relates to the eye. The eye field is the patch of cells in the embryo that becomes the eyes. Sonic hedgehog causes the eye field to split, producing two eyes. When insufficient sonic hedgehog is made, an animal may be born with cyclopia. This is a condition in which only one eye is made. The single eye generally lies in the central axis of the face. An excessive amount of sonic hedgehog may cause too many eyes to be made.
The name "sonic hedgehog" has been criticized. A mutation (change) in the sonic hedgehog gene is involved in certain health problems. Some people think that the name of the gene and its protein sounds too frivolous or demeaning to mention in a discussion with patients or their parents. The gene and protein are sometimes referred to as SHH, which avoids the name problem.
The Future for a Two-Faced Individual
Sonic hedgehog is a very interesting protein, since it has so many effects. The many functions of the protein probably explain why individuals with diprosopus generally have other problems beside duplication of facial structures. They often have brain and heart abnormalities. These may contribute to the death of a two-faced individual soon after birth.
Thankfully, diprosopus is rare, but it often has a sad consequence when it appears. If craniofacial duplication is relatively minor and localized, however, it may be helped by surgery. Frank and Louie was extremely lucky that his particular abnormalities, his surgeries, and the loving care that he received enabled him to survive and enjoy life. It's wonderful that Tres Johnson reached the age of thirteen (and is hopefully older today). He has medical problems, but I hope that treatments improve and that he has a long and good life.
Facts about Frank and Louie from the Toronto Star newspaper
Diprosopus information from Corinne DeRuiter, Embryo Project Encyclopedia, Arizona State University
A report about Lali Singh from the BBC (British Broadcasting Corporation)
SHH (sonic hedgehog) gene facts from the U.S. National Library of Medicine
© 2014 Linda Crampton