Vestigial organs are distinguished. Traces of evolution on the human body. The secret hidden in the egg

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.

Vitruvian Man, Leonadro da Vinci Flickr

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?
Coccyx

Human coccyx diagram / Flickr

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

X-ray of wisdom teeth growing incorrectly / Flickr

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.

Appendix

Remote appendix / Flickr

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

Diagram of the muscles of the human head, the ear muscles are visible above the auricles / Flickr

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

Human body muscle diagram / Flickr

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

Epicanthus - skin fold of the upper eyelid / Flickr

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 the version that the skin fold on the upper eyelid arose as a result of the natural conditions of human habitation - for example, in severe cold conditions or, on the contrary, deserts and hot sun, when the epicanthus is designed to protect the eyes.

Human Vestige- a part of the body or an undeveloped organ that has lost its necessity due to changed conditions of existence, but is still present in the present time, without carrying any semantic load.

Availability rudiments in humans absolutely not conditioned by anything, but the existence vestigial organs continues to be passed down steadily from generation to generation.

The very first thing that comes to mind when discussing rudimentary human organs is coccyx. The coccyx in humans is formed by the fusion of several vertebrae (usually from 4 to 5).

There were times when the tailbone was part of the tail - an organ for maintaining balance, and it also served to give various signals, thereby expressing one’s emotions.

Over time, as man became an upright walking creature, the forelimbs gradually became free and took over many functions, including those performed by the tail, thus the tail lost its importance in the transmission of social signs and in maintaining balance, turning into vestigial human organ.

Appendix- vermiform appendix of the cecum, also is a vestige of man, performing absolutely no functions.

There is an opinion that the appendix used to serve for long-term digestion of solid foods (for example, cereals). There is another opinion on this matter - the appendix served as a kind of reservoir and breeding ground for digestive bacteria.

Appendicitis is a disease in which the appendix (rudiment) becomes inflamed and has to be removed. This operation is very common.

Wisdom teeth They are so called because they sprout much later than other teeth, at the age when a person seems to become “wiser” - 16-30 years.

In most cases, wisdom teeth do not have enough space and they begin to bother, interfering with neighboring teeth and, like the appendix, they have to be removed, which allows us to confidently also attribute wisdom teeth to human vestiges.

Goosebumps- a very interesting protective function of the body, which has lost its relevance in relation to humans, but still exists to this day. Goosebumps appear when triggered pilomotor reflex, the main reasons for which are cold And danger.

When goosebumps appear, the hair on the body rises, which, by the way, also is a vestige of man, for the simple reason that it has lost any meaning and does not perform any useful functions.

One can cite many more different rudiments of a person, such as hair on the head, nails, toes, muscles that move the ears, and so on.

Atavism in humans- the appearance of certain characteristics that were characteristic of our distant ancestors, but are currently absent in others.

The main difference between atavism and human rudiment it is believed that atavism is a certain deviation that occurs in rare cases, for example, abundant hair on the face or the likeness of webbing between the fingers (very rare), and everyone has rudiments, they just lost their meaning over time

Let's look at hair, for example. They play an important role in the “work” of the skin. The sweat and sebaceous glands are located near the hair follicle. The excretory ducts of some of the sweat glands and most of the sebaceous glands exit to the surface of the skin along with the hair. Sebum prevents the development of microorganisms, softens the skin and gives it elasticity. However, if a person’s entire body is covered with hair, including the face, then materialists call this pathology atavism and associate it with inheritance from distant ancestors. Why? Yes, because monkeys and many other animals are completely covered with hair - fur.

Ears to hear. Eyes to see. A nose to breathe and smell. And so on. However, the purpose of some parts of the human body is not easy to explain. Why, for example, do you need the tailbone, the hair on your legs?

It is believed that a person inherited them from distant ancestors. Once upon a time, they brought benefits to people, but over time, the need for them decreased or disappeared altogether - but the “optional” structures themselves remained. They were called rudiments (from the Latin rudimentum - rudiment, fundamental principle).

Before Charles Darwin, scientists believed in all seriousness that rudiments were “created for symmetry” or “to complete the scheme of nature.” Darwin gave a more logical explanation: organs that do not help, but do not particularly interfere with the process of natural selection, gradually degenerate. By the way, the rudiments served as one of the proofs of the theory of evolution.

If all people without exception have rudiments, then atavisms are the lot of a select few. We are talking about features that were completely lost during the process of evolution (for example, a tail or thick hair throughout the body, like animal fur). Scientists explain the appearance of atavisms by the fact that their genes do not completely disappear during evolution, but only lose activity, and can manifest themselves under certain conditions. In the old days, people with atavisms were shunned or shown for money at fairs: “Hurry to see the amazing man-beast and the tailed child!” Today everyone understands that atavism does not make a person inferior. Moreover, such people often resort to the services of plastic surgeons.

Rudiments and atavisms are interesting and useful to biologists. By studying them, you can trace the path of evolution. Theoretically, rudiments and atavisms can benefit humanity as a species: the presence of “extra” entries in the genotype makes the species more flexible in adapting to changing conditions. However, why do ordinary people need low-functional, or even completely useless, organs? Are they of any use or just a hassle?

Rudiments

Rudimentary organs, rudiments (from the Latin rudimentum - rudiment, fundamental principle) are organs that have lost their basic significance in the process of evolutionary development of the organism.

The term “rudiment” in this meaning is widely used in Russian scientific literature, despite the fact that it is the opposite of its original meaning in Latin. In English-language literature, along with it, the more adequate term vestige, derived from Lat. vestigium - trace (in the literal and figurative senses of the word). It is also advisable in Russian to use the term vestigium to designate an organ that has secondarily decreased and/or simplified during evolution, so as not to confuse it with a rudiment - an organ that has not yet reached its final size and structure.

Charles Darwin's analysis of vestigial (that is, vestigial) organs and parts of the body largely contributed to the formation of an evidence base for the origin of man from other representatives of the animal world.

In the 19th century, scientists counted about 180 rudiments. These included organs that are currently recognized as vital: the knee menisci, thyroid, thymus and pineal glands. Today the list of rudiments has been significantly reduced. Opponents of the theory of evolution argue that humans do not have a single unnecessary organ. However, most scientists agree that some organs have largely lost function, which allows them to be classified as vestigial.

A person, unlike a monkey, does not need a tail. He doesn't exist. However, the part of the spine that supports the tail remains - this is the tailbone. The coccyx consists of four to five small vertebrae located below the sacrum. In an adult, these vertebrae fuse into a single, sedentary structure.

Most people don't think about their tailbone. This rudiment does not help, but it does not interfere with life. In women, during childbirth, the tailbone bends back, allowing the fetus to pass through. However, sometimes the coccyx, being richly innervated, becomes a source of very unpleasant pain. They occur when it is excessively bent forward due to individual structural characteristics or injury. What is typical: pain occurs after prolonged sitting, especially on a soft chair. Usually, to eliminate pain, it is enough to recommend that patients sit on a hard surface (in this case, the support is on the ischial tuberosities, and not on the tailbone) and undergo a course of physical therapy. In rare cases, when conservative treatment does not help, the tailbone has to be surgically removed.

The appendix is ​​an extension of the cecum. Its average length is 10 cm (however, the Guinness Book of Records records an appendix with a length of 23.5 cm). Everyone knows what problems the appendix can cause: every year 1 in 200–250 people gets acute appendicitis and more than 1,000,000 operations (appendectomies) are performed. Less is known about the benefits of the appendix. It is believed that it can participate in digestion - beneficial bacteria live in it, and also perform immune and endocrine functions.

What to do with the appendix so that it does not cause problems? Currently, prophylactic removal of the appendix is ​​considered unjustified: it leads to a decrease in immunity, and, in addition, like any operation on the abdominal cavity, it can cause the formation of adhesions. All that remains is to live with the appendix and hope that it does not become inflamed. By the way, Italian scientists have shown that breastfeeding reduces the risk of appendicitis: with a feeding period of 4 to 7 months, the risk is reduced by 10%, and with a feeding period of more than 7 months - almost 2 times!

Mammary glands in men

The mentioned method of preventing appendicitis cannot be recommended for men: their mammary glands are purely vestigial organs. There is no benefit from them, but harm is possible.

With hormonal imbalances (for example, as a side effect of taking certain medications or due to alcoholism), men's breasts can become enlarged and even produce milk. Treatment consists of eliminating the cause of the disorder.

Breast cancer is also possible in men, although it is 100 times less common than in women and has much less social significance. Men, as a rule, notice changes in breast size earlier than women, so treatment is timely. And the cosmetic effect of breast removal for men has less psychological significance.

Body hair

Body hair is a harmless vestige, which, nevertheless, gives women countless troubles. Firstly, it is unaesthetic. Secondly, the hair follicles can become inflamed, but this disease is not difficult to cure. But the hair is some kind of wool, but still wool, which warms a little. It’s not without reason that when it’s cold, your skin gets goosebumps—it’s the hair that rises.

Wisdom teeth

On the one hand, modern people have no need for wisdom teeth - a basic set of teeth is enough. Yes, I don’t want to go to the dentist again. On the other hand, for grinding rough food, it is sometimes useful to have more teeth.

Ear muscles

Humans have anterior, superior and posterior auricular muscles. Our ancestors needed them to set their ears in motion. Some people can also wiggle their ears, but this skill is seen as just a fun addition to facial expressions.

The only advantage of this rudiment is that the ear muscles can be used for a natural face lift using acupressure.

Darwin's tubercle (also tubercle of the auricle, lat. tuberculum auriculae) is a rudimentary formation, a small tubercle on the helix of the auricle of humans and some monkeys, which is a homologue of the pointed apex of the ear of primitive primates and other mammals. Not all people have this structure; According to some data, the frequency of its occurrence is only about 10%.

This anatomical structure owes its name to the fact that Charles Darwin mentioned it in his work The Descent of Man and Sexual Selection as an example of a rudiment. At the same time, Darwin himself called it Woolner's tip in honor of the English sculptor Thomas Woolner, who drew attention to the presence of this formation while working on the sculpture of Puck.

The gene that determines the presence of Darwin's tubercle is autosomal dominant, but has incomplete penetrance (that is, not every person who has this gene will have the tubercle).

Atavisms

Atavism (from Latin atavus - distant ancestor) - the appearance in a given individual of signs characteristic of distant ancestors, but absent in the closest ones. These are long fangs and nails (similar to animal claws), an additional pair of mammary glands, hair all over the body, an analogue of the tail .

Artists and thinkers of the Renaissance, following the ancient Greeks, admired the expressive forms of the human body, the accuracy and coordination of its movements. Admiration, even reverence, sounds in the words of Leonardo da Vinciabout human beauty. In the 16th-18th centuries, many researchers continued to believe that studying human nature was reading a book created by the Creator. It is unlikely that any of them would dare to talk about the imperfection of creation.

Is there really nothing superfluous in our body? The answer to this question was received only at the beginning of the 19th century, when data accumulated on the structure of not only humans, but also other creatures. Comparative anatomy, which by that time had become an independent discipline, helped to understand that humans are structured according to the same plan as vertebrates. Anatomists could not help but notice that the same parts of the body - bones, muscles, internal organs - differ in size and shape in different organisms. Sometimes some parts are completely absent, sometimes they are very small and relatively poorly developed compared to similar parts in other species. underdeveloped organs, which seemed useless, began to be called rudimentary or rudiments.

Rudiments were found not only in animals, but also in humans. For example, in the inner corner of the eye there is a barely noticeable fold called the crescent fold. This is a remnant of the third eyelid, a nictitating membrane well developed in reptiles and birds. It serves to lubricate the eyeball with a secretion secreted by a special gland. In humans, a similar function is performed by the upper and lower eyelids, so the semilunar fold turned out to be superfluous and was gradually reduced - decreased.

Some bones, muscles, internal organs and other parts were also superfluous. For example, the bones of the coccyx, the remains of the caudal vertebrae, which fused, decreased in size and became simpler. The raven or coracoid bone is needed by amphibians, reptiles and birds for attachment of the forelimbs. Mammals managed without it, and small remains of this bone fused with the scapula. Mammals also lost their cervical ribs - what remained were perforated transverse processes of the cervical vertebrae.

A classic example of vestigial human muscles is the ear muscles. They are well developed in many mammals and are needed to direct the ears to the source of sound. Another rudimentary human muscle is the pyramidal abdominal muscle. And the notochord is an elastic axis, thanks to which all chordate animals, including humans, arose; in humans, it turned into a gelatinous mass inside the intervertebral discs.

Scientists have found more and more “extra organs” in humans. Rudiments did not remain a detail of interest only to anatomists, but served for broad scientific generalizations. Thus, Charles Darwin used them as one of the proofs of the origin of man from animals. He explained the presence of rudiments by the fact that during the course of evolution, some organs became smaller and almost disappeared as unnecessary. It follows that man was not created once and for all perfect and unchangeable, but rudiments are only remnants of unnecessary parts of the body that have not yet disappeared.

The German anatomist Robert Wiedersheim published a book at the beginning of the last century in which he listed at least 107 rudimentary human organs that are not suitable for performing any function or that are greatly simplified and cannot function fully. The first include hair on the body, which does not protect a person from the cold, the vermiform appendix of the cecum, which is not capable of digesting rough plant foods, the coccyx, the semilunar fold, and the notochord. The list of the latter includes the pineal gland - the endocrine gland. Apparently, the pineal gland is a rudiment of the parietal eye, which was present in the most ancient vertebrates. Having lost its main function, it acquired a new quality - the production of hormones. The most famous rudiment, the appendix, is an organ of the immune system.

In addition to rudiments, scientists identify atavisms - features lost by humans during evolution and occurring as rare exceptions. The most famous examples are thick body hair, a tail, and additional nipples. Data on the origin of rudiments will probably help to find out which genes are turned on or, conversely, blocked during the development and reduction of certain organs.

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 function, 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.