Everything You Need To Know About Vestigial Tail

Vestigial tail is one of the rarest diseases in the world. It is believed to be due to genetic alterations but the precise cause is not known.

The vestigial tail, also known as the human tail, is a phenotypic extravaganza. Only a hundred cases have been identified worldwide. It is one of the rarest diseases known to date.

This tail grows in the final area of ​​the sacrum, at the level of the tailbone, and is normally made up of connective tissue, muscles, blood vessels, nerves, and skin. However, on other occasions,  other structures such as vertebrae and cartilage may appear.

The vestigial tail is usually removed as soon as the baby is born. However, it happens that this intervention is not feasible and that the person therefore keeps it throughout his life.

In addition,  many cases of vestigial tail have been linked to spina bifida disease,  a congenital problem that causes channels in the spine to not close completely during pregnancy.

Studies also confirm that cases of vestigial tail are  twice as likely in men as in women.

Causes of the appearance of the vestigial tail

In fact, the exact cause of this rare disease is not known. Scientists deduced that it came from a genetic mutation which reactivates a hidden character of our evolutionary development until then repressed in the human genome.

Recent studies and research have also reinforced this theory. To be able to verify that these genes were also in the human genome,  we studied the genes responsible for tail development in mice  and other vertebrate animals.

We humans no longer develop a tail, even though we have the genes for it. Indeed, the regulation of the latter causes cell death or apoptosis of cells  which were intended for the development of this vestigial tail.

To put it another way, we have in our organism sufficient orders and instructions to be able to develop a tail. However, these orders are destroyed. As a consequence of these genes,  a tail can be observed in humans between weeks 4 and 8 of pregnancy.

Due to these rare cases of humans with a vestigial tail,  a heated debate has arisen in the world of medicine and evolution.

Characteristics

It must be taken into account that,  even if we give it this name, in the majority of cases, it is not a tail as such. A normal tail, like that of a cat or dog, is formed from a series of well-differentiated bones, cartilage, spinal cord and muscles that allow its proper movement.

However,  in the cases of vestigial tail which have been described, none of these structures exists  and the few muscles which compose it lack bones on which to unite and on which to insert. Therefore, they are not going to be able to co-ordinate twitch or wiggle, like any animal’s tail would.

However, as we have seen, this tail does indeed consist of:

• Connective tissue.
• Muscle structures.
• Blood vessels.
• Nerves.
• Skin.

All of  these structures will allow the tail to move and contract as the child wishes,  but without any kind of coordination and with many limitations.

In addition,  the size of the vestigial tail varies from case to case. The longest ever recorded was that of a young man in French Indochina. His vestigial tail measured 229 mm.

Sometimes it is very difficult to tell the difference between spina bifida and vestigial tail. For example, a young Indian man, Chandre Oram, became famous thanks to his big “tail”. However, this alteration was not a real tail but a case of spina bifida.