2023-06-27 09:18:38
by Health Editor
The scientific literature reports 40 cases of children born with a soft vestigial tail without bones, cartilages and spinal cord. Theories on the origins and consequent neurological defects
In very rare cases humans can be born with boneless hind appendages tails sometimes up to 18 centimeters long. These are situations that cause anxiety and anguish in parents but also social stigma and superstition, which is why when children born in poor areas of the world are involved, they are often not even taken to hospital and the queue is hidden. To date, official records have counted around 40 babies born with a soft tail that can easily be removed with surgery. Even if the cases are all in all rare, they usually generate a lot of interest, often because the tails are considered the benign and useless remnant of what was once a functional organ. The theory for outdated and controversial.
The vestigial tails
The appendages with which some children are born have historically been considered vestigial tails, that is, structures that once functioned and are present today only in sketchy form. However, this is a misnomer since these things look like nothing seen in nature: in fact, they usually do not contain bone, cartilage or spinal cord but are there, with no clear function. However, this doesn’t mean that these appendages are as harmless as scientists thought.
Darwinian evolution
The misconception about the origin of the queue begins with Charles Darwin himself. More than a century ago Darwin proposed that the beginnings of tails in humans were nothing more than evolutionary accidents or rudimentary remnants of a tailed primate ancestor. As mentioned in an article by Sciencealert In the 1980s, scientists espoused this evolutionary theory, claiming that a genetic mutation eliminated tails in humans, but they rarely reappear.
The two types of queues
In 1985 a landmark document defined two different types of tails that babies can be born with. The first, as already mentioned, is a vestigial tail, originally believed to be inherited from our ancestors. The second is a growth from the coccyx, which sometimes includes the bone and is known as a pseudocoda. Historically the pseudocoda linked to birth defects and not considered vestigial.
Both rare appendages probably represent an incomplete fusion of the spine, known as spinal dysraphism. Therefore, their formation is not a harmless regression of the evolutionary process, but a serious disturbance of the growth of the embryo, most probably caused by a mix of genetic and environmental factors. When a human embryo reaches about five weeks of development, a tail-like structure sprouts, which is somewhat like the first spinal cord. By the eighth week of development, the tail is reabsorbed into the body of the embryo. If it persists until birth, it may indicate the presence of a larger birth defect.
Neurological defects
Infants born with tails tend to have neurological defects as highlighted by a article published in 2008 in which it is reported that vestigial tails are not benign because they may be associated with an underlying dysraphism. Half of the cases examined were associated with meningocele or spina bifida occulta. Children born with tails therefore require more medical attention than a simple surgery and it is not true that it is a benign condition not associated with any spinal cord malformation as reported in the 1985 paper. It is not yet known whether a vestigial tail results directly from the embryonic tail. There is not enough research on where the congenital anomaly lies, also due to the rarity of these cases. Regardless of where a child’s tail has formed, it is a congenital problem and not a harmless vestigial trait.
June 27, 2023 (change June 27, 2023 | 08:41)
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