Biological evolution is defined as any genetic change in a population that has occurred over several generations. These changes can be small or large, very noticeable or not significant.

For an event to be considered an example of evolution, changes must occur at the genetic level of the species and be passed on from one generation to the next. This means that , or more specifically, the alleles in the population are changed and passed on. These changes are noted in the (pronounced physical traits that can be seen) of the population.

A change in the genetic level of a population is defined as a small-scale change and is called microevolution. Biological evolution also includes the idea that all living organisms are related and can be descended from one common ancestor. This is called macroevolution.

What is not related to biological evolution?

Biological evolution does not define the simple change of organisms over time. Many living things experience changes over time, such as loss or increase in size. These changes are not considered examples of evolution because they are not genetic and cannot be passed on to the next generation.

Evolution theory

How does genetic diversity occur in a population?

Sexual reproduction can create favorable combinations of genes in a population or remove unfavorable ones.

A population with more favorable genetic combinations will survive in its environment and reproduce more offspring than individuals with less favorable genetic combinations.

Biological evolution and creationism

The theory of evolution has caused controversy since its inception, which continues to this day. Biological evolution contradicts religion in regards to the need for a divine creator. Evolutionists argue that evolution does not address the question of whether God exists, but attempts to explain how natural processes occur.

This, however, does not avoid the fact that evolution is contrary to some aspects of certain religious beliefs. For example, the evolutionary account for the existence of life and the biblical account of creation are quite different.

Evolution assumes that all life is connected and can be traced back to one common ancestor. A literal interpretation of biblical creation suggests that life was created by an omnipotent supernatural being (God).

However, others have tried to combine the two, arguing that evolution does not rule out the possibility of God, but simply explains the process by which God created life. However, this view still contradicts the literal interpretation of creativity presented in the Bible.

For the most part, evolutionists and creationists agree that microevolution does exist and is visible in nature.

However, macroevolution refers to a process of evolution that is at the species level, and where one species evolves from another species. This contrasts sharply with the biblical view that God was personally involved in the formation and creation of living organisms.

So far, the evolution/creationist debate is ongoing, and it seems that the differences between the two views are unlikely to be resolved any time soon.

Is it possible to predict the direction of evolution, how mutations occur and where natural selection will lead humanity

Evolution is not a matter of faith. Evolution happened in the past and is happening now, and we know its mechanisms. If you have a fairly complete fossil record, when you study fossils from different layers, you will see that they change.

With mammals, this is not so clear, because there are very few fossils. But microscopic marine foraminifers can be extracted in a column from the ocean floor, sedimentary rocks can be dated and, with an accuracy of ten thousand years, you can see how these foraminifers changed. But much of the evidence about how evolution has happened in the past does not explain any mechanisms. We see neither mutation nor selection, only the end result.

How can evolution be observed?

In search of confirmation of the correctness of the theory of natural selection, Darwin studied examples of artificial selection, with the help of which man created various breeds of domestic animals. Crossing different breeds of pigeons, Darwin sometimes received birds that resembled a wild rock pigeon. He came to the conclusion that domestic pigeons, so dissimilar to each other, descended from a single ancestor. //pxhere.com

A person on a historical scale does not live very long, so we can observe a rather conditional evolution. We will not see how the worm turns into a fly, that is, how one form passes into another. From my point of view, the best example of evolution is not even Darwin's pigeons, but goldfish: in fact, this is goldfish, and it has changed a lot in two thousand years. From Chinese chronicles it is known when different forms appeared: goldfish, red fish and fish without a dorsal fin. The Chinese were engaged in artificial selection: when an interesting mutant appeared, they isolated it from other fish and propagated it.

The most famous example of the study of evolution in the laboratory is the experiment of Richard Lensky, in which he and his laboratory staff have been observing twelve populations of E. coli for thirty years. Escherichia coli. During this time, almost 80,000 generations of E. coli have already changed, many interesting mutations have occurred, but for a non-specialist, this is how it was Escherichia coli, so it remained. New strains with new properties have appeared, but it is impossible to talk about the emergence of a new species.

The concept of species itself is not defined. When a person becomes infected with the HIV virus, it is because of a single viral particle. If the patient is not treated and he dies of AIDS in ten years, viruses will be found in the body that differ from each other by 15%. This means that a serious evolution is taking place. The influenza virus is also evolving all the time. A person who has had the flu will never get sick again with the same strain of the virus: he has immunity for life. And therefore, if the influenza virus had not evolved, there would not have been constant epidemics.

What is a view? When did Australopithecus become human? If we want to divide a continuously evolving line into species, this inevitably means that at some point we will classify mother and daughter as different species. There are such jumps in evolution, but they happen very rarely due to one specific mechanism, when the entire genome is duplicated. This is not possible in mammals. So, while the monkey turned into a man, there was no such thing that parents and children differed greatly. Nevertheless, at the input we have a monkey, and at the output we have a man.

Evolution rate

The rate of evolution is not constant, and we must remember that we measure it in generations, not in years. Fifty mouse generations pass in one human generation, so the mouse can evolve faster. When new conditions arise, evolution also speeds up. But there are so-called living fossils, coelacanths and ginkgoes, which have not changed outwardly for 200 million years, and mammals have traveled a gigantic path over the same period of time.

According to the Hardy-Weinberg law, the rate of evolution of a genome fragment that is not affected by selection is equal to the rate of mutation. The reasons are clear: if selection does not work, then the new mutation is no better and no worse than the old version. Therefore, the new variant has the same probability of gaining a foothold in the population as any copy of the old variant. Surprisingly, the mutation rate in all eukaryotes that have been studied is more or less constant and amounts to 10-8 nucleotides per generation.

This refers to neutral evolution, which has nothing to do with evolutionarily significant changes - elk antlers and butterfly wings. Neutral evolution is a change in amino acid and nucleotide sequences that do not affect the fitness of the organism and are not under selection pressure. Random, fitness-independent changes in the frequencies of genetic alleles in a population are called genetic drift. Thus, genetic drift reigns over neutral mutations, and selection over beneficial and harmful ones. Selection that increases the frequency of beneficial mutations is called positive selection. Selection that rejects harmful mutations is negative.

The theory of neutral evolution is the assumption that most mutations at the molecular level are neutral in relation to natural selection. Thus, a significant part of intraspecific variability, especially in small populations, is explained not by the action of selection, but by the random drift of mutant alleles that are neutral or almost neutral.

The evolution of those nucleotides that affect traits and fitness is under selection pressure, and therefore not at all neutral. A conservative protein, such as a histone in humans and peas, will differ by only one amino acid, meaning it will not evolve at all. And some protein important for adaptation can evolve at a high speed. We are currently growing a mushroom in an experiment Podospora. We have eight lines, and in six years the same protein has evolved in seven lines. It turns out that in order to adapt to the conditions of cultivation, this fungus wants to break down a specific protein.

There are entire segments of the genome that do not affect traits and fitness. But a lot of non-coding DNA affects traits. In humans, the total length of such segments is at least ten times the length of the coding segments.

Not everyone can drink milk as an adult. In all mammals, as soon as they stop eating breast milk, the lactase enzyme that processes milk sugar is turned off. A person has a mutation that breaks the shutdown mechanism and allows you to drink milk all your life. It is assumed that this was due to the emergence and development of cattle breeding: the Polynesians do not have a gene that allows them to drink milk in adulthood, because none of the ancestors of the Polynesians ever drank milk or raised cattle in their lives. A mutation that allows you to drink milk, - this is a replacement of just one nucleotide, not even in the coding gene, but 30 thousand nucleotides from it. Two different mutations arose separately in northern Europeans and Bantu pastoralists in Africa, but they are very close, ten nucleotides apart. And that piece of non-coding DNA breaks there, which is responsible for the complex process of turning off the work of the lactase gene. So if a segment is non-coding, then this does not mean at all that it does nothing. There are transcription factors that bind to non-coding DNA and regulate gene expression. A person has 99% non-coding DNA, and 90% "lounging" DNA. It turns out that a lot of non-coding DNA performs some functions.

In order to understand from the evolution of the genome how traits will change, we must know the mapping from genotype to phenotypes, but this is usually unknown. Suppose I was forbidden to look at signs, but was allowed to look only at genotypes. And I will see that in my population for a hundred generations in such and such a place there was a replacement of the letter A with the letter G. What does this mean in terms of characters? No one knows.

If you give a scientist some new genotype and say: “We caught an animal with such and such a genome. What can you say about it?”, then the only thing this scientist can do is compare this genome with those already known and say: “This animal is a beetle, because its genome is similar to the genome of a beetle.” But if we couldn't cheat like that, we wouldn't say anything at all. We wouldn't know if it has legs or tentacles, what size it is, what it eats.

DNA changes randomly, primarily due to DNA polymerase errors. These changes are usually harmful, because when you take something that is already working and accidentally change it, you will most likely make it worse. But surprisingly, sometimes mutations are useful.

At the same time, we do not understand at all how the accumulation of beneficial mutations leads to the emergence of a new life form. Chimpanzees differ from humans in 30 million letters, that is, 1% of the genome. Most of these differences have nothing to do with traits: if 20 million letters in my genome were replaced with "chimpanzee letters", I would not change. But some letters, on the contrary, are important. The question arises: how many letters must be changed in the chimpanzee genome, or rather, how many “words” to make a person out of it? How strong was the selection that supported the hominizing mutations of monkeys? We don't know.

Natural selection

Using the method of random walks, it is impossible to find in the whole variety of proteins one point that corresponds to the optimal implementation of the function of each protein. Fortunately, such optima are not points, but vast areas. And the search for the optimum in the course of evolution is carried out not by the method of random walks, but by means of directed selection. Directionality arises due to the fact that random deviations in the “wrong” direction worsen the working qualities of the protein and are discarded. And random changes in the “right” direction are remembered and saved.

The more harmful mutations an organism has, the less likely it is to cheat selection. Of course, there is always some random component, but if the mutation is completely harmful, then its carrier is doomed to extinction. If it is moderately harmful, then you may be lucky and he will survive. Human medicine resists selection. Many people a hundred years ago would have died at an early age, but now they successfully reproduce. But there is evidence that selection in the human population still continues to work. And it affects not only survival, but also fertility.

Very interesting data have recently been obtained: the genes that contribute to education are under the negative pressure of natural selection. It has long been understood that the higher a person's level of education, the fewer children they have on average. But now this has been confirmed at the gene level, that is, alleles have been identified that are associated with a higher level of education. And it turned out that if you carry such an allele, then you have a higher level of education, and fewer children.

The brain is the most complex part of the human phenotype in terms of genetics. Severe dementia is caused by mutations in five thousand genes, and every year several hundred more genes are added to this list. This, by the way, to the question of why a man needs his monstrous intellect. In modern industrialized societies, the higher a person's level of education, the greater the income and life expectancy. It would seem that there are only advantages from education, but the selection is directed in the other direction. And among Pithecanthropes, who did not receive any education, the selection for some reason acted in favor of the ability to learn.

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Education is determined by the environment, but the fact that something is more determined by the environment does not mean that it is not a feature. A good example is height and weight. Weight is determined by the environment much more than height. Even in the Holy Scriptures it is said that none of us can, despite all our efforts, add even one cubit to our height. But it doesn't say that none of us can put on 10 kilos, because it's very easy to do if you have money and McDonald's. But this does not mean that height is a sign, and weight is not a sign.

Until now, some people believe that evolution is a theory that still needs to be proven. But natural selection is a very simple thing. If there is a genetically determined variability in milk yield in cows and we slaughter half of the cows with a lower milk yield, the average milk yield will be higher in the next generation. It is not very clear what can be refuted or proved here.

Modern evolutionary biology is based on the fact that DNA, RNA and proteins are the basis of life on Earth. In a living cell, there is a directed flow of information from DNA, which is the original genetic text, consisting of four letters: A, T, G and C. The text is written in the form of sequences of these letters, which are called nucleotides and are stored in the DNA double helix, in one from two chains. During transcription, RNA is synthesized on the DNA template, which is identical to this text, with the difference that in RNA, instead of T, there is U. The RNA text is a cast from the corresponding DNA text.

The resulting RNA, called messenger RNA, or mRNA, is translated using the genetic code as a sequence of amino acid residues in proteins. There is a translation of the text of DNA and RNA nucleic acids from the four-letter alphabet of nucleotides into the twenty-letter alphabet of amino acids. Sometimes in texts, for various reasons, errors occur: substitutions of one or more letters, repetitions, disappearance of entire fragments. Such errors - mutations - underlie variability.

All laws of evolution are considered only through the prism of modern ideas about the molecular organization of living things. Two hundred years ago, Darwin understood the key mechanisms of evolution without knowing anything about the relationship of genotypes and mutations to the phenotype, and this is extremely interesting from the point of view of history. On an intuitive level, he established a connection between variability, heredity and selection. But now it is wrong to study evolutionary biology starting from the Darwinian understanding.

How it all started

The very first fossils of the living are dated 3.5 billion years old - these are bacterial communities, stromatolites in Australia and South Africa. These two places were located close and formed the so-called Pilbara Craton. Several papers have now come out claiming that life was already 3.8 billion years ago. The remarkable thing is that there is a lower bound: life cannot be older than 4.2 billion years, because the Moon was knocked out of the Earth at that time. Everything on our planet was melted and red-hot, and even if some life existed before that, a complete reset had to happen. So for the emergence of life, it took either 700 million years, or even 400.

Approximately half of the E. coli genes Escherichia coli there are clear relatives in the human genome. In the other direction, the ratio is smaller, but the person simply has more protein-coding genes: twenty thousand versus three thousand. But it also happens the other way around: in a nematode C.elegans dozens of genes that only other nematodes have, but no one else has. Whether these genes have evolved so much that we no longer see the similarities, or whether they arose out of nowhere, no one knows.

Last universal common ancestor (LUCA) -

last universal common ancestor. No fossil remains of LUCA have survived, so it can only be studied by comparing genomes. LUCA is believed to have lived 3.5–3.8 billion years ago, during the Paleoarchean era.

All living species are equally ancient and descended from LUCA. But some species have changed more and others less. The evolutionary approach says that all living things are interconnected. At the level of fundamental genes, what a person has should also be in a crocodile. The most fundamental process for all living things is protein synthesis. Why exactly this? It would seem that DNA synthesis is also an important process, everyone has it. But now they say that the last common ancestor of LUCA may not have had DNA, only RNA and proteins.

This situation is possible: DNA could have appeared later and turned out to be such a useful acquisition that, through horizontal transfer, it spread throughout all living things. It is most likely impossible to verify this, because it is impossible to catch a live LUCA, or even find its remains: this is a derived concept, and not some specific and specific organism. But in the first approximation, if everyone has something, then LUCA probably had it. Or, shortly after his appearance, it spread like wildfire through all his descendants.

You can try to talk about the evolution of LUCA itself and look into the history before it. Imagine that everyone has two related proteins that are clearly descended from a common ancestral protein. So they are products of gene duplication and divergence that have been going on since before LUCA. With the help of such reasoning, we conclude that LUCA itself has already passed a very difficult selection and was the product of a long evolution. There were many proteins in it, clearly descended from each other. If you ask Evgeny Kunin, he will say that all the most interesting things happened before LUCA. And from a certain point of view, he is right: no one knows anything about the origin of life. The RNA world hypothesis is widespread: maybe it was, or maybe it wasn’t. Everything sounds very plausible, but we have no facts. Evgeny Kunin argues that the ribosome cannot arise spontaneously, but since there are 10,500 universes, it happened in one of them.

EVOLUTION (lat. evolutio - deployment) - one of the forms of movement in nature and society; a slow, gradual quantitative change, leading under certain conditions to a new quality by way of a leap, a break in gradualness, a revolution. Evolution and revolution are two inextricably linked forms of movement, development of nature and society.

Brief political dictionary. M., 1988, p. 461.

Evolution (Shapar, 2009)

EVOLUTION (lat. evolutio - deployment) is a process of change, development, in the views on the mechanism of which neo-Darwinists are not always united. According to some, evolution is the result of a series of successive small shifts from random mutations in accordance with momentary needs. Others believe that evolution has a certain internal trend, followed by the development of species, subject to certain guidelines already laid down in the genes.

Evolution (Ilyichev, 1983)

EVOLUTION (from Latin evolutio - deployment), in a broad sense - a synonym for development; processes of change (primarily irreversible) occurring in animate and inanimate nature, as well as in social systems. Evolution can lead to complication, differentiation, an increase in the level of organization of the system (progressive evolution, progress) or, conversely, to a decrease in this level (regression); evolution is also possible while maintaining the general level or height of the organization (the evolution of geological systems, languages).

Evolution (Golovin, 1998)

EVOLUTION - Neo-Darwinists are not always united in their views on its mechanism. According to some, it is the result of a series of successive small shifts from random mutations according to momentary needs. Others believe that evolution has a certain internal trend, which follows the development of species, subject to certain guidelines already laid down in the genes. According to others, evolution occurs in leaps, starting with major alterations that occur at some selected, nodal points of the evolutionary path, where species differentiation occurs.

Evolution (NFE, 2010)

EVOLUTION (from Latin evulutio - deployment) - in biology - a change in living matter during the development of an organism or in a sequence of generations of organisms. The term "evolution" was first used by the English theologian, lawyer and financier M. Hale (1677), speaking of the structure hidden in the human seed, or the image, "in the evolution of which the connection and formation of the human organism should consist." In the modern sense, the term "evolution" was first used by G.

Revolution and evolution (Lopukhov)

REVOLUTION AND EVOLUTION - from a philosophical point of view, two natural, dialectically justified ways of developing any natural, sociocultural, psychophysical and other systems.

Revolution - a radical, deep, qualitative, spasmodic change in the state of a developing object or a revolution in any particular area of ​​culture (science, art, technology, everyday life, pedagogy, etc.).

Evolution is a slow, gradual qualitative and quantitative change, leading over time and under certain conditions to profound qualitative changes.

Evolutionary epistemology

EVOLUTIONARY EPISTEMOLOGY is a modern epistemological concept that considers cognition as a "folded" form of objective actions. The ideas of E. E. were developed by the Swiss scientist J. Piaget (1896-1980). The ideas of the evolutionary theory of the development of scientific knowledge are present in the works K. Popper. The supporters of this concept are K. Lorenz, E. Oyser, G. Vollmer (Germany). J. Piaget considered cognition as a special form of structuring the relationship between the environment and the organism. Cognitive-intellectual activity is a set of operations that are internalized (placed "inside" the subject) actions. The task of cognition is the balance between the environment and the organism, hence the commonality of all cognitive structures that develop under relatively similar conditions. There are no fundamental differences in the cognitive activity of man and animal ...

Evolution (Agajanyan)

EVOLUTION [lat. evolutio deployment] - an irreversible process of historical change of the living. From numerous undirected mutations as an elementary evolutionary material, natural selection forms such combinations of traits and properties that lead to the emergence of adaptation of organisms. E. - the process of historical development of living nature. The term "E." applicable both to wildlife in general and to individual organs, organ systems, cells, organelles and molecules.

Evolution (Comte-Sponville)

EVOLUTION. Progressive change, often slow and always gradual, of beings or systems. Resists permanence (no change) and revolution (abrupt and massive change). Since the 19th century, the term has owed its wide distribution to a large extent to various theories of evolution (especially Darwin's theory, although the scientist himself used it with great caution), which aimed to explain the origin and development of species of living organisms.

Nature is constantly improving itself. But evolutionary change is extremely slow. Compared to human life, of course. Only for billions years the existence of the Earth, nature was able to achieve such perfection and diversity of life as we see now.

Darwin suggested that the driving forces of evolution, or factors influencing the development of wildlife, are:

• heredity and variability individuals of one kind ;

Heredity and variability

It is known that individuals of the same species are similar, but still not the same. They slightly differ in signs of external and internal structure, behavior. These differences may affect the possibility of survival. More likely to survive and leave offspring are those individuals whose distinctive features correspond to the habitat. These changes can be passed down to offspring. As a result, the number of individuals with such traits in the next generation increases.

Struggle for existence

Natural selection

The struggle for existence leads to natural selection - the predominant survival and reproduction of the more adapted individuals of the species and the death of the less adapted.

The action of natural selection throughout life many generations leads to the accumulation of small useful hereditary changes and the formation of adaptations of organisms to the environment.

An inhabitant of European forests, the hedgehog has sharp spines that serve to protect against predators. Their emergence is the result of natural selection. Even a slight roughening of the skin could help the distant ancestors of the hedgehog survive. For many generations, in the struggle for existence, individuals with more developed spines had the advantage. It was they who could leave offspring and pass on their hereditary changes to him. Gradually, new useful traits spread within the species, and all individuals of the European hedgehog became the owners of spines.

Acting for a long time, the driving forces of evolution lead to the formation of adaptations of living organisms to various environmental conditions, to the transformation of some species into others, to the emergence of more complex life forms based on simpler ones.

Adaptation (fitness)

Adaptations are the features of living organisms, thanks to which they exist in nature. Useful signs, arising in individual organisms as a result of variability, help them survive in the struggle for existence. These features are preserved as a result of natural selection and are transmitted to descendants by inheritance. So, generation after generation, the signs of animals and plants gradually change for the better for them. evolutionary changes. And that is why all living organisms are so well adapted to the conditions in which they live.

Speciation

Speciation is the result of evolution. A population over the course of many generations may be isolated from others populations of this species (for example, being at a great distance from them). Acting for a long time, natural selection leads to the accumulation of many differences between isolated and other populations.

As a result, individuals of different populations lose the opportunity to interbreed and produce offspring. The emergence of insurmountable biological barriers to crossing leads to the process of speciation.

Speciation led to the emergence of two species foxes- common foxes and corsac foxes. In the north, natural selection contributed to the survival of the largest individuals (the larger the body size, the less heat the body loses). As a result, the common fox species was formed. In the southern regions, on the contrary, natural selection was aimed at preserving the smallest individuals (the smaller the body size, the more heat the body gives off, while it does not overheat). As a result, the form of the Korsak Fox was formed.

To date, biological evolution has been fully confirmed on the basis of scientific facts accumulated in various branches of biological science. Evidence of evolution is based on a comparative study of the external and internal structure, development and life processes of modern representatives of ancient extinct species. For this, there are scientifically based cytological,