One of the main proofs of the theory of evolution can be observed with your own eyes, since they occur quite often and have been well studied during this time. Signs that appear in an individual and that do not correspond to the currently widespread species are called atavisms. Atavisms- these are traces preserved due to the fact that they were once natural for an individual at a lower stage of development. Over time, the individual improved its functional and external qualities, gradually getting rid of unnecessary features. However, in the genetic code, traces of an individual of the old sample have been preserved, so the possibility of atavism is not an exception, but a documented fact.
Atavisms are present in an individual from birth, and cannot form over time. Often this is a hereditary trait that is clearly expressed during direct contact.
Atavisms. Brainstorm
Vestigial organs
In addition to atavisms, which are essentially pronounced signs of an individual at a previous stage of development, there are also rudiments. They are essentially undeveloped and unused organs of the body. However, despite the absence of a large functional load, vestigial organs are considered signs of the normal appearance of each creature. We can only say that over time the need for them will disappear, and their very formation will cease as unnecessary. Atavisms and rudiments are two sides of the same question about the functioning of and.
Atavisms in theoretical evolution
Charles Darwin, the founder of the theory of evolution, considered atavisms and vestiges the main sign that people and other creatures developed over time into other species. Its supporters were so carried away by the idea of searching for such non-functioning organs that they identified about two hundred of them in the human body. At this point, their theories have been refuted by evidence that most organs have their own functional purpose. However, this does not exclude the fact that a genetic predisposition to the formation of atavisms and rudiments is inherent in every organism.
Atavisms. Popular science with Anna Urmantseva
Atavisms in animals
There are many quite striking examples of atavisms that occur most often in order to judge their regularity. In the animal world there are atavisms- Not unusual. Examples of atavisms include the wings of flightless birds such as penguins, ostriches and kiwis. An atavism observed in horses can be called an extra toe, which they inherited from their ancestors. However, these atavisms can be called successful, since they found their application in survival conditions and helped creatures adapt to changing conditions.
Human atavisms
The situation with atavisms is much more complicated in. Atavisms are perceived by the human body as part of it and do not cause unnecessary inconvenience, but in everyday life this can become a disturbing factor.
Among the most pronounced examples of atavisms are the following:
- the elongated coccyx, also known as the tail process, occurred as a result of the fact that, according to Darwin’s theory, man has common roots with the monkey, which also had a tail;
- thick hair - the abundance of hair on the body and face reveals in a person the signs of his ancestors, which allowed them to exist in various climatic conditions. Over time, this cover began to decrease, however, in some cases, it was transformed into atavism. It is expressed in excess hair on the face (woman's beard) and body (thick, long hair);
- additional pair of nipples - the presence of three pairs of nipples on the body indicates the origin of man as a mammal. These organs are often not functional, although there are cases when extra mammary glands work along with the main ones.
The difference between rudiments and atavisms in humans
Heart of a Dog - Atavism
Vestigial organs are considered a natural feature of the individual, even though their use is limited. There are several functional rudiments, which, nevertheless, are not atavisms in the full meaning of the word. They are typical for any representative of humanity:
- appendix - despite the myth that it is the most useless for humans, it performs some functions, in particular, it removes a small amount of enzymes that are useless for the body;
- wisdom teeth - appear in people as a result of the fact that in the past the body had a need to change teeth due to using them too quickly. Such teeth were replaced with new ones, but according to the laid down code, the body is still trying to reproduce their presence;
- The tailbone is a residual part of the tail, but it cannot be called completely useless. It is present in all members of the human species and is the norm.
- Ear muscles are also a mandatory norm, but do not carry functions useful for the body.
The emergence of atavisms
The reasons for the occurrence of atavisms lie in the most complex genetic code, which was created by millions of ancestors of an individual. Over time, the individual evolved into new forms, but did not lose the inherent data that remained from past generations. When two individuals meet, each of which has a pronounced tendency to form atavistic and rudimentary organs, the birth of a child with full-fledged signs of atavism is not uncommon. However, the likelihood of encountering carriers with such strong chromosome sets that will lead to the appearance of atavisms is not high. Atavism is considered a rare but regular anomaly in individuals of any species, so the study of atavisms is a successful step.
For onlookers, some oddities in a person’s appearance are another reason to groan and gossip; for an educated and tactful person, it is an opportunity to think once again about the path of human evolution.
Rudiments and atavisms are not deformities, much less a reason for ridicule, but possible “mistakes” of nature. And for scientists these are important signs, evidence of evolution.
What are atavisms
The presence in an individual of characteristics that were inherent in its distant ancestors is called atavism. What could it be? For example, thick hair on the body, including the face. Or a tail growing above the tailbone. Multi-nipple is also included here. Once upon a time, back in the century before last, atavisms and rudiments were a clear confirmation of Darwin's theory. Then scientists were so carried away by the search for “useless” organs in the human body that they counted almost two hundred of them. Fortunately, over time, most of the organs from this “Darwinian” list were, so to speak, rehabilitated. Scientists have proven that their functionality is quite high.
It turned out that:
- some organs produced the necessary hormones;
- others turned out to be necessary at one time or another in the development of the organism;
- still others began to act under certain external conditions;
- and the fourth became “substitutes” for organs that failed.
That is, the same tailbone is not a direct reminder of the tail, but an organ that serves to attach certain ligaments and muscles. Let's take other examples: the appendix is not at all a useless tail-like appendage, but organ, in which the necessary microorganisms multiply.
By the way, if we talk specifically about atavisms, then this term is not truly scientific. And trying to determine the signs of atavism means acting in an anti-scientific way. Judge for yourself: increased body hair is supposedly a “hello from the past”, a reminder of who it came from there was a man. But other external deformities, for example, enlargement of fingers on the limbs, are a clear pathology, and in no way a parallel with a similar stage of development of the human body. That is, if these deformities do not have a direct resemblance to their ancestors, then this is a pathology. And if they do, it’s an atavism. But in both cases, the cause of such anomalies is a genetic failure.
By the way, if you are an adherent of the evolutionist theory, you must definitely meet people with fins and gills, and other characteristics that our animal ancestors possessed.
What are rudiments
But rudiments are considered to be undeveloped organs of the human or animal body. Let us give eloquent examples:
- Ear muscles. Some mammals really need them: it helps them direct their ears to a certain sound stimulus. A person no longer needs such an “option”.
- Semilunar fold in the inner corner of the eye. This is a remnant of the third eyelid, a fairly well developed nictitating membrane in birds and reptiles. It lubricates the eye with the necessary secretion, but in humans, the upper and lower eyelids cope with this mission. So the fold became small, turning out to be unnecessary.
Darwinists blindly denied the new role of “unnecessary” organs, but over time it was proven that not everything is so simple in the human body. One cannot simply say that the same appendix is a reminder of our ancestors; no, today it is an organ of the human immune system.
Let's try to dispel some popular myths about rudiments and atavisms.
5 myths about atavisms and rudiments
Myth 1. Nipples in men are vestiges. But there’s nothing like that: they didn’t function in any way among our male ancestors either. The explanation for their presence is simple - in the early period of embryonic development, people are unisex, sexual differences appear later, which is facilitated by special hormones.
Myth 2. A wisdom tooth is a genetic disorder. But this is atavism; strong molars helped our ancestors grind plant foods. We could chew them now, but in most cases they grow incorrectly, which causes a lot of inconvenience and leads a person to a dental surgeon.
Myth 3. The connection of the esophagus to the trachea in humans is meaningless. This is not true: mucus in the respiratory tract can be removed through the esophagus, but we can say that this structure is responsible for “saving space” and allows you to breathe through the mouth, which is very important for a severe runny nose.
Myth 4. Tonsils and adenoids are rudiments. This is not true at all! These organs are necessary for the growing body: they help launch an important mechanism for the production of protective antibodies. Once the mechanism has started working, the tonsils begin to shrink, and their function is taken over by other organs.
Myth 5. All “unnecessary” organs can be removed without disastrous consequences. This is certainly not the case. The main proof is that most organs either have several functions (and if one is “outdated”, then others are very relevant), or they turn out to be necessary in certain external situations.
Why do atavisms appear?
Dad doesn’t have a ponytail, and mom doesn’t, but the baby was born so unusual. Why? How could this happen? The notorious laws of genetics must be blamed here. Our entire appearance is programmed by the genes of our ancestors (genes for repeating traits). For every human trait, two genes are responsible: mother’s and father’s. They can be different or the same, strong or weak. If dad has a weak tail gene and mom has one, when they meet, they have every chance of giving birth to a child with a tail, because having united, the weak genes have become stronger.
But in fairness, we note: the chance of such a meeting is extremely small, and hidden genes of this kind are very rare.
In this article we will look at atavisms and rudiments: we will give their definitions and characteristics, and give examples. It should be understood that these are not synonyms. After reading this article, you will learn what the difference is between concepts such as atavisms and rudiments.
What are rudiments?
Rudiments are not parts of the body that turned out to be completely unnecessary. They have only lost, at least partially, their original purpose. Organs considered to be rudiments play a certain role in the functioning of the body. Try, for example, to take away the wings of an ostrich... Without them, will this animal be worse or better? The answer is obvious: although its wings are less functional than those of other birds, the ostrich needs them. Its wings, for example, allow it to maintain balance when moving.
Wings of a Kakapo parrot
The kakapo parrot is found in New Zealand. He, like an ostrich, cannot fly at all. However, it has small wings, the muscles on which are atrophied, as well as an underdeveloped keel. This animal is nocturnal. He runs on the ground and loves to climb trees. Nevertheless, he still does something from the life of birds. A parrot, when climbing to great heights, occasionally jumps, simply using its wings for gliding. However, this jump most often ends unsuccessfully. The "bird" often flops on the ground. The parrot is not capable of climbing trees. However, this is his main occupation. But it is fully adapted for flight, since the body of this bird is identical in design to other parrots (with the exception of certain aspects). But the kakapo cannot fly at all. However, he tries, which sometimes ends sadly.
Are rudiments necessary?
Thus, rudiments can be useful, but they are always a remnant of something that was much more effective in the past. This parrot's wings are vestigial because they have lost the ability (partially) to perform their former functions. It's the same story with the ostrich. He is no longer able to fly, but he still has wings (as well as hollow skeletal bones, which are typical for full-fledged birds).
Man is no exception here. We also have atavisms and rudiments. Examples of the latter are the appendix, which is an organ that is certainly useful. However, among our ancestors its significance was more significant - it played a more important role in the digestion of food. Therefore, the appendix is a vestige. But sometimes it is somewhat more difficult to determine what role rudiments and atavisms play in humans. For example, answering the question why we need molars today is no longer so simple. It is known that the pain and troubles they cause sometimes force us to turn to a surgeon.
The importance of the appendix in the human body
One of the most famous human vestiges is, perhaps, the appendix. The concept of appendicitis (inflammation of this appendix) is closely related to it. In surgical practice, interestingly, operations for appendicitis are among the most common. The disease often harbors serious complications in the form of an abscess (an abscess forms in the abdominal cavity) and peritonitis (the tissue covering the abdominal cavity becomes inflamed).
However, the appendix also has useful functions. It maintains microbiological balance in the intestines, promotes adequate digestion, and also supports local immunity, since it contains a large amount of lymphoid tissue.
What are atavisms?
One of the most important evidence of evolutionary theory is atavisms. They are found quite often and today are well studied. Atavisms are characteristics that appear in a particular individual and do not correspond to the currently widespread species. These are traces that have been preserved because they were once natural to an individual that was at a lower stage of evolution. Over time, she improved her external and functional qualities, gradually getting rid of unnecessary signs. But traces of an old-style individual are preserved in the genetic code, which is why atavisms sometimes arise. They are present from birth in an individual and cannot be formed during life. This is often a hereditary trait.
From what ancestors can rudiments and atavisms appear?
The presence of rudiments and atavisms proves the existence of evolution. And now you will see this. Mammals, as well as birds, are without exception the ancestors of reptiles. In turn, reptiles were the ancestors of amphibians, amphibians - fish, etc. It can be argued that only from our ancestors can atavisms appear. However, parallel branches will not be able to influence each other in any way. For example, a person can have atavisms from mammals (fur, nipples, tail) and even reptiles (the so-called “snake heart”). As you probably already guessed, we also only have rudiments from mammals, amphibians, reptiles and fish. And atavisms and rudiments from parallel evolutionary branches (in our case, birds) are impossible. Also, birds will never show signs of mammals, but they can show signs of reptiles. Thus, the presence of rudiments and atavisms in animals (as in humans) is not an accident, but a natural event, predicted by evolutionary theory.
Atavisms in humans
Examples of atavisms in the human body can be given as follows.
1. Elongated coccyx, or caudal process. It appears as a result of the fact that, according to Darwin, man has common roots with the ape, which had a tail.
2. Thick hair. In humans, the abundance of hair on the face and body reveals signs of our ancestors. These characteristics allowed them to exist in different climatic conditions. Such cover began to decrease over time, but in some cases it transformed into atavism. This atavism is expressed in excess hair on the face (beard in women) and on the body (long thick hair).
3. There is an additional pair of nipples. The fact that man descended from a mammal is evidenced by the presence of three pairs of nipples on the body. These organs are often not functional, but there are cases when, along with the main ones, extra mammary glands also work.
Why do atavisms not appear in everyone?
Even if the external manifestation of a trait is completely lost, fragments of the genetic “programs” that ensured the development of this trait in the ancestors can remain in the genome for a long time. One of the main and, perhaps, the most delicate principles of regulation of gene function in the body is post-transcriptional control. That is, everything that the gene responsible for the development of this or that atavism has “accumulated” is “cleaned up” in the developing cell of the embryo. Thus, an unnecessary sign is not formed. However, under special circumstances (extreme effects on the embryo, mutations), these gene programs can still work. It is then that we encounter anomalies that can sometimes be fatal (for example, in the case of an oval window, an unclosed interatrial foramen).
The fate of the rudiments
Rudiments, by their genetic essence, are practically “unsuppressable”. Therefore, they are found in most individuals (for example, in humans - coccygeal vertebrae, molars, etc.). It is important to note that these signs usually do not cause significant harm to the individual. Perhaps they are even a potential basis for the development of a useful trait in the future. It can be assumed that they will not be removed from the genetic code by evolution any time soon. Or they won’t even be confiscated at all.
Thus, there is a big difference between such concepts as “atavism” and “rudiment”. The difference is that rudiments appear in almost all individuals, while atavisms appear only in some.
Charles Darwin's opinion
What does Charles Darwin think about this? The founder of evolutionary theory believed that atavisms and rudiments are the most important sign that people, like other creatures, developed over time into other species. Proponents of this idea were so carried away by the search for non-functioning organs that they found about 200 of them in the human body. Their theories have now been refuted. Of course, no one denies the existence of rudiments and atavisms, but their meaning is a controversial point. Most of these organs have been proven to have a functional purpose. However, this does not exclude the possibility that the genetic predisposition, due to which atavisms and rudiments are formed (their examples are not limited to those presented in this article), is inherent in every organism.
Vitruvian Man, Leonadro da Vinci
The presence of vestigial organs, as is known, is one of the proofs of Darwin's theory of evolution. What kind of organs are these?
Organs that have lost their importance during evolutionary development are called vestigial. They are formed in the prenatal state and remain for life, in contrast to the so-called provisional (temporary) organs, which only embryos have. Rudiments differ from atavisms in that the former are extremely rare (continuous hair in humans, additional pairs of mammary glands, development of a tail, etc.), while the latter are present in almost all representatives of the species. Let's talk about them - rudimentary human organs.
In general, the question of what is the role of rudiments in the life of a particular organism and what, in fact, should be considered as such, still remains quite difficult for physiologists. One thing is clear: vestigial organs help trace the path of phylogenesis. Rudiments show the presence of kinship between modern and extinct organisms. And these organs, among other things, are proof of the action of natural selection, which removes an unnecessary trait. What human organs can be considered rudiments?
Human coccyx diagram
This is the lower part of the spine, which consists of three or five fused vertebrae. It is nothing more than our vestigial tail. Despite its rudimentary nature, the coccyx is a fairly important organ (like other rudiments, which, although they have lost most of their functionality, still remain very useful for our body).
The anterior sections of the coccyx are necessary for the attachment of muscles and ligaments that are involved in the functioning of the organs of the genitourinary system and the distal sections of the large intestine (the coccygeus, iliococcygeus and pubococcygeus muscles, which form the levator ani muscle, as well as the anopococcygeus, are attached to them ligament). In addition, part of the muscle bundles of the gluteus maximus muscle, which is responsible for hip extension, is attached to the coccyx. We also need the tailbone in order to correctly distribute the physical load on the pelvis.
X-ray of wisdom teeth growing incorrectly
Wisdom teeth
These are the eighth teeth in the dentition, commonly referred to as the number eight. As you know, “eights” got their name due to the fact that they erupt much later than other teeth - on average at the age of 18 to 25 years (in some people they do not erupt at all). Wisdom teeth are considered rudiments: at one time they were necessary for our ancestors, but after the diet of Homo sapiens changed significantly (the consumption of solid and tough foods decreased, people began to eat heat-treated food), and the volume of the brain increased (as a result of which nature “had to” reduce the jaws of Homo sapiens) - wisdom teeth resolutely “refuse” to fit into our dentition.
These “bullies” among the teeth every now and then strive to grow at random, which is why they greatly interfere with other teeth and general oral hygiene: due to the incorrect placement of the “eights” between them and neighboring teeth, food gets stuck every now and then. And it’s not so easy for a toothbrush to reach wisdom teeth, so they are often affected by caries, which leads to the removal of the diseased tooth. However, if wisdom teeth are positioned correctly, they can, for example, serve as support for bridges.
Removed appendix
Appendix
On average, the length of the appendage of the cecum in humans is about 10 cm, the width is only 1 cm. Nevertheless, it can cause us a lot of trouble, and in the Middle Ages, “intestinal disease” was a death sentence. The appendix helped our ancestors digest roughage and, of course, played a very important role in the functioning of the entire body. But even today this organ is not at all so useless. True, it has not performed a serious digestive function for a long time, but it performs protective, secretory and hormonal functions.
Diagram of the muscles of the human head, the ear muscles are visible above the auricles
Ear muscles
They are the muscles of the head surrounding the auricle. The ear muscles (or rather, what is left of them) are a classic example of vestigial organs. This is understandable, because people who can move their ears are quite rare - much less common than people who do not have a tailbone, appendix, etc. rudiments. The functions that the ear muscles performed in our ancestors are quite clear: of course, they helped move the ears in order to better hear an approaching predator, rival, relatives or prey.
Human body muscle diagram
Pyramidalis abdominis muscle
It belongs to the anterior muscle group of the abdominal area, but in comparison with the rectus muscle it is very small in size, and in appearance it resembles a small triangle of muscle tissue. The pyramidalis abdominis muscle is a vestige. It is significant only in marsupials. Many people do not have it at all. For those who are the lucky owners of this muscle, it stretches the so-called linea alba.
Epicanthus - skin fold of the upper eyelid
Epicanthus
This rudiment is characteristic only of the Mongoloid race (or, for example, of the African Bushmen - the most ancient people on the planet, the descendants of which, in fact, we are all) and is a skin fold of the upper eyelid, which we see with an eastern section of the eyes. By the way, it is thanks to this fold that the effect of “narrow” Mongoloid eyes is created.
The causes of epicanthus are not exactly known. But most researchers are inclined to believe that the skin fold on the upper eyelid arose as a result of the natural living conditions of a person - for example, in severe cold conditions or, on the contrary, deserts and hot sun, when epicanthus is designed to protect the eyes.
Diagram of the human larynx, number 5 indicates the Morganian ventricles of the larynx
Morganian ventricles of the larynx
This organ is a sac-like depression located between the true and false vocal folds on the right and left sides of the larynx. They are important for creating the so-called common resonator chamber, that is, a resonant voice. Apparently, our ancestors needed the Morgani ventricles in order to create a series of certain sounds and protect the larynx.
Some other organs can also be classified as rudimentary organs; in addition, representatives of certain races may have their own rudiments that are not characteristic of other races. For example, steatopygia among the aforementioned Bushmen and related Hottentots is the deposition of large amounts of fat on the buttocks. In this case, fat reserves play the same function as the humps of camels.
