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?
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.
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 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 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.
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.
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.
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
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.
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.
Steatopygia / ©Flickr
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.
According to the theory of evolution, humans descended from monkeys. For millions of years, due to this process, the appearance, character, and mental capabilities of Homo Sapiens changed, distancing it from its ancestors. The era of technological progress has brought the human species to the highest level of evolutionary development. The presence of common ancestors with the animal world is now presented in the form of rudiments, examples of which will be discussed in this material.
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Characteristic
Vestigial organs- certain parts of the body that have lost their original meaning during evolutionary development. Previously performing the leading functions of the body, now they carry out secondary ones. They are laid at the initial stage of embryonic formation, without fully developing. The rudiments are preserved throughout the life of the individual. The function that they carried during standard development is significantly weakened and lost in their ancestors. The modern world cannot fully explain the essence of the presence of such underdeveloped organs in the physiological structure.
Vestigial organs are the primary evidence of evolution for Charles Darwin, who spent many years observing the animal kingdom before coming to his revolutionary conclusion.
Such body parts directly confirm family ties between extinct and modern representatives of the planet, helping to establish the path of historical development of organisms. Natural selection, which serves as the basis, removes unnecessary traits while improving others.
Examples of rudiments among the animal world:
- bird fibula;
- presence of eyes in underground mammals;
- residual hip bones, partial cetacean hair.
Rudiments of man
TO vestiges of man include the following:
- coccyx;
- wisdom teeth;
- pyramidal abdominal muscle;
- appendix;
- ear muscles;
- epicanthus;
- blinking ventricle.
Important! Examples of rudiments are common among different people. A few tribes and races possess such organs, characteristic only of their species. Each example of rudiments in humans can be identified and described in detail to bring clarity to the topic under discussion.
Types of basic rudiments
Coccyx represents the lower part of the spine, including several fused vertebrae. The function of the anterior part of the organ is to attach ligaments and muscles.
Thanks to it, there is a correct, uniform load on the pelvis. The coccyx is an example of a rudimentary tail in modern humans, which served as a center of balance.
Wisdom teeth - these are the most delayed and obstinate bone formations of the oral cavity. The original function was to assist in the process of chewing hard, tough food.
Modern human meals include more thermally processed foods, so during evolution the organ has atrophied. Located last in the row, wisdom teeth often come out in people of conscious age. A common phenomenon is the absence of “eights” and partial eruption.
Morganian ventricle- paired sac-like depressions located in the right and left parts of the larynx. The organs help create a resonant voice. Apparently, they helped the ancestors reproduce certain sounds and protect the larynx.
Appendix- vermiform appendage of the cecum. It helped distant ancestors digest rough food. Currently, its functions have diminished, but the important role of concentrating the formation of beneficial microorganisms has remained. The presence of this organ in humans has a significant negative quality - the possibility of inflammation. In this case, it needs to be removed surgically. The microflora after surgery is difficult to restore, and infectious diseases become more frequent.
Ear muscles also belong to the rudimentary features surrounding the human auricle. Ancient ancestors had the ability to move their ears, enhancing the hearing needed to avoid encounters with predators.
Attention! It is strongly not recommended to deliberately get rid of some of the listed organs, because they still perform secondary functions.
Vestigial organs of certain races
Epicanthus - vestigial vertical continuation the upper fold of the eye. The exact causes and functional features of this organ are not thoroughly known. There are suggestions that the skin fold protected the eyes from weather conditions. Characteristic of the Bushmen.
The pyramidalis abdominis muscle continues the list of vestigial organs, representing the triangular shape of muscle tissue. The main function is to tighten the linea alba.
Steatopygia - fat accumulation in the upper parts of the buttocks. Has a storage role, like a camel's hump. Characteristic of some African tribes, although this rudiment or pathology is not fully understood.
Human atavisms and differences from rudiments
There are peculiar external signs of the kinship of the human species with the animal world. Atavism is a sign present among the ancestors, but not inherent in the current species.
Those who encode it are preserved, continuing to pass on its properties to the next generation. They can be called “sleeping”; they awaken only at the birth of individuals with an atavistic trait. This happens when genetic control is lost, or due to external stimulation.
The main difference between atavism serves as the manifestation of traits in individual individuals. During embryonic development, a human individual partially follows the path of distant ancestors. At certain weeks, the embryos have gills and tail-like processes. If these signs persist during childbirth, they represent atavism.
Atavisms and rudiments alike serve as evidence theories of evolution, but if the first signs have no functions, then the second have a certain useful meaning. Some types of this phenomenon can pose a threat to health or disrupt some vital processes. Some people still speculate on the topic: is the appendix a norm in the form of a vestigial organ or an atavism.
Attention! Many atavistic signs are easily removed surgically, making life easier for the wearer.
Examples of atavisms
Many people still confuse atavisms and rudiments, attributing one to the other. The first ones have two types of signs:
- physiological;
- reflexive.
Examples of human atavism should be thoroughly studied so that the difference becomes clearer.
If people do not exhibit external signs of one thing or another, this does not mean that the genes for the signs are absent, but have the ability to manifest themselves in the future.
Atavisms are extremely rare in the population and appear only in cases where ancient ancestral genes unexpectedly appear in humans.
Here are the most common and obvious types of human atavism, making up the following list:
- excessive hairiness;
- protruding tail;
- cleft lip;
- multiple nipples in humans;
- second row of teeth;
- hiccups;
- grasp reflex in newborns.
The listed features clarify the debate among many about whether wisdom teeth, hidden or erupted, are a rudiment or an atavism. They are characteristic of many species, but not all occur. If wisdom teeth or other rudimentary parts of the body were found only in single specimens, then it would be possible classify them as atavism.
We study what rudiments are, examples
12 rudiments in humans
Conclusion
Homo Sapiens is a complex organism with a diverse system of life activity, changing millions of years of evolution. Everyone has examples of their types. The main difference between atavism and rudimentary body parts is that only a few possess them, and a person can easily live without them.
Atavisms and rudiments, examples of which will be discussed in our article, are irrefutable evidence of the evolutionary theory of the development of living organisms. What do these concepts mean and what is the significance of their discovery for modern science?
Evidence of evolution
Evolution is the development of all living things from simple to complex. This means that over time, organisms replaced each other. Each subsequent generation had more progressive structural features, which determined their adaptation to new living conditions. This means that organisms belonging to different systematic units must have similar features.
For example, the forelimbs of birds consist of identical sections. These are the shoulder, forearm and hand. But since birds are adapted for flight, this limb turns into wings, and in aquatic inhabitants it changes into flippers. Such organs are called homologous.
Another proof of the theory of evolution is analogies. So, both insects and bats have wings. But in the former they are derivatives of epithelial tissue, and in the latter they represent a fold of skin between the fore and hind limbs. These organs have different origins, but share common structural and functional features. This phenomenon arose as a result of divergence of characteristics, or divergence.
Atavisms and rudiments, examples of which are studied by comparative anatomy, are also direct evidence of the interconnection of all living things with each other.
What is a rudiment?
Some organs are said to be “rudimentarily developed.” This means that it is not enough for the full implementation of the intended functions. Indeed, organs that, in the process of evolution, have lost their original meaning are called rudiments. On the one hand, they are developed to a certain extent, and on the other, they are at the stage of extinction. Typical examples of rudiments are changes in the shape of the auricle and the degree of development of the muscles that surround it. Our ancestors needed to listen every minute for the approach of danger or long-awaited prey. Therefore, the shape of the shell was sharper, and the muscles ensured its movement. For a modern person, the ability to move his ears is unlikely to be useful in everyday life. Therefore, individuals with such skills can be found very rarely.
Examples of rudiments in humans and animals
Insufficiently developed organs inherent in ancestors are found quite often in animals. Examples of rudiments are the presence in humans of a coccyx, which is a remnant of the caudal spine, as well as wisdom teeth, necessary for chewing rough and unprocessed food. At this stage, we practically do not use these parts of the body. The appendix is a vestige that humans presumably inherited from herbivores. This part of the digestive system secretes enzymes and participates in digestion processes, but is significantly shortened compared to its ancestors. For comparison: in a person its average length is about 10 cm, and in a sheep or camel it is several meters.
The list of human rudiments continues with the third eyelid. In reptiles, this structure moisturizes and cleanses the outer membrane of the eye. In humans, it is motionless, small in size, and the above functions are performed by the upper eyelid. The scar on the upper palate of a person is also a rudiment - these are the rudiments of the next row of teeth, which a person does not need.
The rudiments of animals are the hind limbs of whales hidden inside the body, and the halteres of dipterous insects, which are a modified pair of wings. But snakes’ limbs are not at all developed, since due to the peculiarities of their musculoskeletal system, the need for them is completely absent.
Rudiments: photos of plants
Plants also have vestigial organs. For example, wheatgrass weed has a well-developed rhizome, which is an underground shoot with elongated internodes. Small scales, which are vestigial leaves, are clearly visible on it. Since underground they will not be able to perform their main function - carrying out photosynthesis, there is no need for their development. The rudimentary pistil in the form of a tubercle in the staminate flower of cucumbers is also a rudiment.
What are atavisms?
Another proof of evolution is atavisms. We can say that this concept is the opposite of rudiments. Atavisms are the manifestation in individual individuals of characteristics characteristic of their distant ancestors. Their presence also indicates a certain degree of kinship in a number of generations. In the early stages of embryo development, there is both a tail and gill sacs. If embryogenesis occurs correctly, these structures stop developing. If the development process is disrupted, individuals may be born with structural features that are unusual for them. Therefore, the tailed boy and the amphibian man are not just a fantasy.
Human atavisms
In addition to the appearance of a tail, typical atavisms in humans are excessive body hair. Sometimes it significantly exceeds the norm. There are known cases when hair covered the entire human body, except for the palms and soles of the feet. The appearance of additional mammary glands on the body is also considered an atavism, and this can occur in both women and men. This trait is inherited from mammals that gave birth to many children. At the same time, there was a need to feed all of them at the same time. A person has no such need.
The second row of teeth is also a feature inherent in our distant ancestors. For example, a shark has several rows of them. This is necessary for predators to effectively capture and retain prey. There is an opinion that microcephaly can also be considered atavism. This is a genetic disease that causes a reduction in the size of the brain and skull. At the same time, all other body proportions remain normal. This entails mental retardation.
Man displays some signs of animals in the form of reflexes. For example, hiccups are a typical feature of ancient amphibians. This reaction was necessary for them to pass water through their respiratory organs. And which is especially strongly developed in children, is a manifestation of that in mammals. They grabbed onto their parents' fur to avoid getting lost.
Atavisms of animals and plants
Examples of ancestral traits in animals include the appearance of fur or hind limbs in cetaceans. This is evidence of the origin of these animals from extinct ungulate mammals. Atavisms are also the development of additional fingers in modern horses, mobile limbs in snakes and In primroses, an increase in the number of stamens to 10 is sometimes observed. This is exactly how many the ancestors of modern plants had. Although modern species have only 5 stamens.
Causes of evolutionary changes
As you can see, rudiments and atavisms appear in many species of plants and animals. This indicates a certain degree of relationship between representatives of different systematic units within the same kingdom. Evolutionary changes always occur in the direction of their complexity, as a result of which living organisms have the opportunity to better adapt to certain living conditions.
Having examined examples of rudiments and atavisms, we were convinced of the generality and consistency of the theory of evolution.