You will be hard-pressed to find an animal with features that are not rudimentary or useless: atrophied eyes, discarded wings, or males with breasts, to name just a few.
All these are indicators of history, the inheritance of distant relatives, properties that are no longer used and that evolution will tolerate for a while or use again if necessary, as in the case of eyes that can be found under the skin some moles, penguin wings which are used as fins or insect wings that begin to they serve as a kind of halter.
From the very core of each cell to the architecture of our organs, the human body also bears traces and wounds that are the result of a long and comparative evolutionary history.
Naturally, not all parts of our body served a purpose, otherwise we would have to ask ourselves why we (but not Neanderthals) we have a chin. It would be ridiculous to seek expediency at any cost.
And indeed, despite the wonderful proportions of da Vinci's Vitruvian Man drawn in a circle and a square, our physical properties are mostly a Homer Simpson-worthy collection of mismatches.
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So, for example, in the case of men, the question arises as to what is the purpose of the urethra, which passes right through the center of the prostate and whose function is in no way related to urination.
The result is unnecessary pain that occurs years later when the prostate becomes inflamed or enlarged.
This makes absolutely no sense, except that we know that until recently people didn't even live long enough to suffer from this kind of disease. Even though it doesn't make any sense, it's still evolution.
Imperfection appears in nature due to the need to find compromise solutions between need and conflicting selective drives.
This means that some essential properties can evolve in a positive direction regardless of the fact that their owners suffer from irritating side effects.
The appendix is another good example.
And if recent research states to the fact that it has some secondary advantages related to the immune system or that they can also serve as a reservoir for good bacteria in case of infections, there are also a large number of potential anatomical solutions that would be more effective and less painful than this one.
Today, when we need it, we can overcome the problem with emergency surgery, but the very existence of a worm-like appendix in our stomachs is definitely a bad idea.
Another similar example is the external scrotum.
Many mammals have it, including us, and we all know that it plays an important role in cooling the testes during sperm production.
Yet many mammals - elephants, hyraxes, anteaters, dugongs, elephant shrews and golden moles - have testicles inside their bodies, where they are more protected.
Therefore, the external scrotum is useful, but not essential.
Hidden ovulation is another strange phenomenon that is almost unique to our species.
Men do not perceive the moment when women are ready to conceive.
We find much more sense in baboons, mandrills, chimpanzees and bonobo monkeys - in their females, sexual irritation is recognizable by the appearance, turgidity and color of the genitals, as well as by the release of certain smells.
This means that even the dullest males will sooner or later realize that it is time to perform their sacred duty, while this does not happen with humans.
For us, but also for some other species like the gray langur from Southeast Asia, ovulation is hidden. This creates a great uncertainty in the males who do not know whether the copulation, which was achieved after a lot of pain, was successful or not.
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The list of evolutionary oddities just goes on.
If you are able to move your cochlea like elephants, that means you still have useless but still functional muscles in your ears.
The caudal vertebrae that are fused below the pelvis are actually the remains of your tail, and the coccyx still serves as an attachment point for some muscles.
Ask someone who has fallen down the stairs and hit the edge of the stairs hard.
Those who suffer from debilitating back pain understand well the imperfection of human bipedality, the collection of locomotor inefficiencies that made us human.
For a moment, let us also consider our strange posture, perhaps the most imperfect of all our adaptations.
The human spine did not evolve out of the blue.
The flexible spine of quadrupeds or brachiators (a pre-existing limitation and evolutionary inertia) has been corrected, meaning that the weight of the whole body has become a load on one axis, and the legs have been relieved.
The result is a crooked spine and vertebrae subjected to extreme pressure. Nerves and muscles adjusted as much as they could, but not enough to prevent sciatica, hernia and flat feet.
So if, after all that effort to rise on its hind limbs, that biped starts to spend the whole day sitting at a desk or behind the wheel of a car, then it is an active search for pain caused by imperfection.
So why did we become bipedal? The question is actually more complicated than it sounds.
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An upright posture is believed to have enabled us to run long distances and to be more mobile when moving. A quadruped will crush us at 100 meters, but as cross country runners we are not bad at all.
As bipedals, we can crawl if necessary, and we can also walk, run or cross a river.
All of that is true, but the fact remains that in the vast savanna, almost all animals are four-legged and that they do quite well as such.
It is also believed that bipedalism gave our ancestors the ability to present themselves to predators as a vertical rather than a horizontal silhouette (much more visible to the average cat), and standing in tall grass gives a better view of predators from a distance.
And of course, the upright position freed our hands and arms from movement, so we could use them to handle tools or carry food or children.
But did we become bipedal to free our hands, or did our hands become free when we became bipedal?
Alas, the numbers don't add up because the first Stone Age technologies appeared in Africa about 3,3 million years ago, which is some 700.000 years before the appearance of the human race, and as far as we know, only Australopithecus and Kenyanthropes with their arboreal traits roamed the area around Lake Turkana.
Then why did technology arrive first, and only then complete bipedalism. What is the cause and what is the effect?
Remembering the time bipedalism cost us all those expensive requirements listed above, it must have made sense from the start, because otherwise those treetop doppelgangers of ours would have prevailed.
Other human evolution experts still believe that the initial step towards bipedalism is related to thermoregulation.
When the species that live in the border zones between forest and grassland explore territories that are in the sun, without shade, they have a serious problem to maintain the body temperature within certain physiological limits, and this especially applies to the brain which is not exactly in able to tolerate overheating.
Savannah quadrupeds have developed certain countermeasures that we lack. The solution our tribe resorted to is the reduction of surface areas under the sun in order to keep the body temperature under control.
At the same time, our ancestors gradually lost their fur and developed sweat glands.
If things happened that way, then it is possible that adaptation to thermoregulation caused appropriate processes (flexible movements, release of upper limbs, etc.) that make bipedalism a good strategy regardless of the consequences it caused.
It is also possible that, because of all these compromises, and despite its undoubted merits, bipedalism evolved slowly and timidly over four million years, after several failed attempts and failed experiments.
One such example is the Ardipithecus, which was a forest biped that moved through the branches.
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For two-thirds of hominin natural history (the period 2-6 million years ago), our ancestors, relatives and relatives preferred a hybrid solution: living in trees to defend themselves against predators (with the help of persistent and ancient features such as curved fingers and long arms) and the prudent decision to explore the glades in search of food.
That's how she lived Lusi (the oldest preserved hominin fossil) who died by falling from a tree.
At the time, it represented the most intelligent possible strategy for those who were just becoming brave hunters, but at the same time they were prey for cats and giant eagles. Baboons and other primates do the same thing today.
So it would be best to forget the story of human evolution that begins with the heroic "coming down from the trees" in order to conquer the savanna on foot. We became complete bipeds during the awakening of the human race.
Many of our companions still curse that moment to this day.
Walking upright on two legs has become a big risk when at the same time the way of eating changes, when the brain starts to enlarge and when we should give birth to offspring.
The pelvis is not able to expand much because otherwise we would not be able to stand upright. Consequently, the baby's head passes with considerable difficulty.
If we could reset the entire process, the ideal engineering solution would be to give birth directly from the stomach, but this is not possible because the channel through which our birth takes place is actually a modified version of the reptilian way (egg laying) and that of early mammals where everything happened through the pelvis.
Thus, compromises became inevitable - fixing the gestation period at nine months and giving birth to helpless babies whose brains reached only one-third of their development, while the remaining two-thirds had to complete their developmental journey later.
In any case, it remains an imperfect solution to the end, especially when we think not only of the number of mothers and newborns who died during childbirth, but also of the fact how painful it all is for women.
The transition to bipedalism generated negative consequences in almost every part of our body.
Human feet moving on their soles have to withstand a lot of pressure. Our neck, with that heavy, wobbly ball on top of it, became a weak point.
The stomach, with all its internal organs, is exposed to different types of injuries. The abdominal tissue is pushed down by the force of gravity, which predisposes to hernia and prolapse of the uterus.
You can feel the consequences on your own face.
The next time you catch a cold and feel the muscles pressing down on every opening in your face, think about the fact that your blocked maxillary sinuses have discharge channels directed upwards towards the nasal cavities - against the force of gravity.
Because of this, they are completely ineffective and can easily become clogged with mucus or similar slimy substances.
It all looks like a poorly designed system, but the fact is that in quadrupeds the entrance of the maxillary sinuses faces upwards and that way everything works as it should.
But with us, former quadrupeds, faces only recently reached a vertical position and this is the result.
Archaeologist Andre Leroy-Guran was right when he said that human history began with good feet, rather than bigger brains.
It was all a great temptation, especially at the very beginning.
Then we started loving it all and with those long legs we became primates on the move, with a strong sense of curiosity and no restrictions that could hold us back.
*This article is originally published in the publication "The MIT Press Reader"and is published here with permission.
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