What is a rudiment? Rudiments and atavisms - the quirks of nature or evidence of evolution?

What is a rudiment? It is part of a plant or animal organism that no longer fulfills its function for which it is intended. Living organisms abound in rudimentary structures, and their study provides additional opportunities to prove evolution.

Examples of rudiments in the animal kingdom

What are rudiments? Examples can be found everywhere. For example, dandelions, although they reproduce without fertilization, they still have flowers and form pollen. Among the insects, you can meet flightless beetles, which have fully formed wings, hidden beneath the solid overgrown elytra.

Reptiles like pythons still have a rudimentary pelvis that is not attached to the vertebrae (as in most vertebrates) - it simply floats in the abdominal cavity. This is proof that the snakes originated from the four-legged reptiles. Some lizards carry rudimentary, rudimentary legs under their skin that are not visible from the outside.

Many animals have rudimentary eyes. For example, cave underwater inhabitants such as fish (Mexican tetra and salamander of the Typhlotriton spelaeus and Proteus anguinus species) are blind, but have rudimentary eyes. The eyes of the Mexican tetra have a lens, a degenerative retina and an optic nerve. Blind salamanders have eyes with pupils, which cover the eyelids from external light.

The whales have a rudimentary pelvis and hind paws. The bones of the legs are present in the body of the whale, but are not attached to the rest of the skeleton. Instead, they are simply embedded in the animal tissue. This is evidence of the evolution of whales from land ancestors, followed by loss of hind limbs and pelvis. All that remains rudimentary in modern whales is the remains of these structures.

Human Rudiments

What is a rudiment? This is a part of the body that has lost its direct purpose in the process of evolution, for example, the human appendix, which once performed an important function, and now does more harm than good. The coccyx is the remains of the caudal bone of distant ancestors of primates - this is the residual part of the embryonic tail, which forms in the human body, and then decomposes and is "eaten" by the immune system. And some people are still, although extremely rare, born with tails (atavisms).

Some people can wiggle their ears, although this property is inherent in cats and other animals and is necessary for the localization of sounds during hunting. The ancestors of people, as is known, were herbivores, and the teeth were necessary for chewing and chopping plant food. More than 90% of all adults have so-called wisdom teeth. These useless teeth sometimes grow up incorrectly and can cause severe pain. Often people just get rid of them.

The appearance of "goosebumps" in humans is also a rudimentary feature. This reaction usually occurs when it is cold or scary. Muscles at the base of each hair act to lift the hair up. In animals, this function is associated with heat retention. The same can happen if the animal is under threat. This time "standing fur" makes it possible for the beast to look more threatening and menacing.

Irrefutable Evidence of Evolution

To study the standard phylogenetic tree, it can be noted that each species has a unique pedigree. Each organism has its own unique cycle of common ancestors, connecting it with them. It should be expected that organisms carry evidence of this genealogy history. What is a rudiment? In biology, these are anatomical and molecular features that are nonfunctional.

What is a rudiment? For example, the wings of birds are very complex from the anatomical point of view, structures specially adapted for controlled flight, but there are birds that can not fly. A striking example is ostriches, whose wings can be called rudimentary organs with confidence, since they are needed not for flight, but rather for balancing during running and marriage dances.

The bewilderment of scientists

Rudimentary structures lead to bewilderment of naturalists throughout history. This question was of interest to scientists long before Darwin first proposed his universal theory of the origin of species. Many scholars of the eighteenth and nineteenth century, such as Johann Wolfgang von Goethe (1749-1832), Georges-Louis Leclerc, Comte de Buffon (1707-1788) and Georges Cuvier (1769-1832) studied the problem.

Sixty years before the publication of Darwin's Origin of Species, the outstanding French specialist in the field of anatomy, Geoffrey St. Hilaire (1772-1844), studied the rudimentary wings of the cassowary and ostrich. He was at a loss why nature always leaves "traces of an organ", which is no longer needed. Ten years later Jean-Baptiste Lamarck (1744-1829) defined some rudimentary structures in his Zoological Philosophy.

Atavisms

Atavisms are certain characteristics inherent only in a small group of organisms. Examples are human tails (coccygeal projection), additional or webbed fingers, abnormal hairiness, hyoid muscle in dogs, and so on. Some genes, for example, fluff of a baby, are simply deactivated after delivery. What are rudiments and atavisms? This is just the tip of the iceberg of evolutionary evidence.

The characteristics of atavisms are:

1) presence in the adult stage of life;

2) absence of signs from parents or recent ancestors;

3) extreme rarity in the population.

One of the most dramatic atavisms is human tails. Some of them are soft, containing only muscles, blood vessels and nerves. Sometimes there may be cartilage. These tails can be removed surgically. Atavismas include the presence of a large number of nipples (more than 2).

Riddles of Evolution

What are rudiments in biology? These are organs that have lost their immediate purpose and are no longer performing their direct functions. If all living organisms have descended from a common ancestor, then the loss or acquisition of various functions and structures is conditioned by historical macroevolution.