Over time as a species, however, we evolved past the need for such an organ, which is why the majority of humans no longer grow them.

Most humans grow a tail in the womb, which disappears by eight weeks. The embryonic tail usually grows into the coccyx or the tailbone. The tailbone is a bone located at the end of the spine, below the sacrum. Sometimes, however, the embryonic tail doesn’t disappear and the baby is born with it. This is a true human tail.

Growing a true human tail is extremely rare. Sometimes, when babies are born, their parents might think they have a true tail when actually they don’t. This is called a pseudotail. Pseudotails are usually a symptom of an irregular coccyx or of spina bifida as opposed to a remnant of the embryonic tail from the womb.

What Causes Human Tails?

To be clear, true human tails are exceedingly rare. They are often referred to as archaic or even as “oddities” because of their rarity. They are also found twice as often in males as they are in females and are not found to be passed down within families.

It’s a commonly held belief that the origins of the human tail lie in the ancestors of humans. Scientists believe that humans eventually adapted out of needing tails and so no longer grow them.

Some scientists, however, have recently speculated that vestigial tails are linked with abnormalities in the spinal cord and column. Specifically, these scientists see vestigial tails as a part of spinal dysraphism or of a tethered spinal cord.

Whether human tails are the remnants of a bygone era or a sign of spinal irregularity, there is not much you can do to avoid having one.

What Are Human Tails Made Of?

Some common characteristics a human tail are:

• They contain muscles, connective tissue, blood vessels, and nerves
• They are always covered with skin and located on the tailbone
• They can be as long as 13 centimeters
• Sometimes, they can even move or contract

Human tails do not contain bone, cartilage, or the spinal cord.

How Do You Remove a Human Tail?

Qualified doctors can surgically remove a human tail in a very safe and simple procedure.

During this surgery, the surgeon untethers the outer part of the tail. Because human tails are generally also linked to spinal issues, surgeons are always very careful to perform extensive presurgery tests and to not damage the area further.

While it is unnecessary to remove human tails for any specific health-related reason, they are often uncomfortable, painful, or otherwise inconvenient to have. Across the developing world, there have been cases of patients as old as 17 years of age revealing their human tails to doctors for the first time because the tails have eventually begun to cause them pain.

Some people born with tails keep their tails for many years, while some parents opt to remove their baby’s tail at birth. In some cases, it’s not entirely apparent that the tail is a true tail until years later.

Social and Societal Meanings of Human Tails

In some parts of the world, human tails are largely stigmatized and babies born with human tails are considered to be pariahs. This is one main reason why someone might avoid seeing a doctor about their tail. In other societies, such as some parts of India, tails are considered to be blessings or gifts from the gods.