What if Humans Had Kept Their Tails?

You'll notice that you don't have a tail, unlike the majority of primates, if you quickly glance over your shoulder.

It's also quite beneficial. We truly should be appreciative of the shift.

What if everything turned out completely differently? Here's how the world may have seemed if our forefathers had retained their tails, minus the requirement for a hole in the back of your pants.

But some individuals do have tails, right?

Technically, we all had one long before we were born, although briefly.

Human development includes short tails, which begin to appear about the sixth week of pregnancy. Even yet, this little addition to the spinal column has up to a dozen vertebrae. Half of them resorb within a week, while the other half fuse into the coccyx, also known as the tailbone.

Whatever people, primarily males for some reason, are born with the tip of this embryonic "tail" remaining in place because nature enjoys a little diversity. The appendage is fully equipped with sufficient blood vessels to maintain its health and even muscles that, under some circumstances, can cause it to move. They don't include any of the original vertebrae, though.

Contrary to protrusions brought on by different diseases or malignancies, these 'real tails' are so uncommon in human births that it would be difficult to discover more than a few dozen examples of them in the medical literature.

However, they do happen. Most are quickly removed immediately after delivery since they are too little to be of much use and could draw unwelcome attention.

However, if we all had long tails, the situation would be very different.

Why don't we have tails, you ask?

Small animals with primate-like physiologies first appeared around 10 million years after a comet wiped out the dinosaurs 66 million years ago.

These creatures, like modern new and old world monkeys, lemurs, tarsiers, and bush babies, possessed long tails, perhaps to aid in balance when moving through the treetops.

Some of these tails developed into an additional thumb throughout time, giving them a degree of dexterity that most of us would kill for. In fact, it was so helpful that it happened again in different populations of primates.

Unfortunately for us, a group of monkeys without tails first arose some 20 million years ago. Gorillas, chimpanzees, bonobos, and orangutans are among their descendents. Not to mention, of course, us humans.

According to a recent study, the reason for this loss was due to an Alu sequence, an errant piece of genetic code, which interfered with the function of a gene essential for producing tails.

Bo Xia, a graduate student at New York University who studies stem cell biology, made the discovery. In order to find mutations that could explain why the apes lacked tails, Xia compared the genomes of nine species of tailed monkeys with those of six species of apes.

Here he discovered a gene known as the T-box transcription factor T. (TBXT). Experiments conducted by a Russian researcher by the name of Nadezhda Dobrovolskaya-Zavadskaya over a century ago revealed that mutations in this gene resulted in mice with shorter tails.

The Alu element in the TBXT gene was examined more closely and found not to be very disruptive. But Xia discovered there were actually two jumping genes present, and they were quite near to one another.

Together, they may completely muck up how the gene is expressed, explaining why humans and other primates have nothing dangling from our butts. A clean rear and a flat tailbone that are ideal for sitting, squatting, and moving about on two legs were eventually created over time with the assistance of alterations in other genes.

This may explain the dynamics, but it doesn't explain why a TBXT gene mutation in an ape ancestor spread so extensively throughout several hominid species all those years ago.

So tell me, what would have happened if our forefathers had maintained their tails?

We can only guess why, when its tail refused to develop, one of our ancestors fared so much better.

The entire incident is even more unexpected when we take into account the change's increased likelihood of causing neural-tube defects like spina bifida, which cause the spinal cord to protrude after birth. So letting the tail end go must have been to our great advantage.

Tails are anchored in certain significant anatomical structures that surround the hip region, making them more than just an extension dangling from the end of the spine. Together, these muscles, ligaments, and bones bring the body into alignment, enabling balance and—in the case of some monkey species—the capacity for grasping and manipulating objects.

Consequently, if people possessed tails, they would likewise require hips and muscles in order to use them. If not, they would be little more than a large sausage dragging down the ground. Nobody would want that, either.

This would not be a minor adjustment. To let them to move more easily between the branches, tail primates typically have longer spines with a few extra vertebrae.

The musculoskeletal specializations of apes, on the other hand, include shorter lumbar portions that strengthen their spines. Stronger backs can better withstand the force of falls and jumps, perhaps allowing for larger bodies or quick leaps into low branches and descents to the earth.

An ancient theory claims that the muscles in your tail were never wasted. They were instead appropriated to serve as a sturdy framework that supports our abdominal organs including the bladder and intestines.

It helps to hold back any urine and feces that could accidentally be pushed out while allowing us to apply tremendous pressure to our stomach without causing the meaty portions to rupture.

In light of this, modifications to the rest of our bodies would be necessary if humans have tails akin to those of monkeys.

We'd need to reactivate those pelvic floor muscles to support those additional muscles and bones, not to mention the additional brain space we may need to provide for in order to perceive and operate our ingenious new limb. This may necessitate giving up being a biped completely, in addition to increasing the danger of several hernias and maybe some incontinence.

It's debatable whether the absence of a tail helped our ancestors stand on their own two feet to any significant degree, just as it's debatable why it disappeared in the first place.

But if our forefathers had clung to their tails, it's probable that humans wouldn't have developed at all.