Evolutionary progress. Progressive evolution Higher and lower

Does progressive evolution make sense? Part II. The Glorious End of Genetic Determinism

V.V. Velkov, Institute of Biochemistry and Physiology of Microorganisms RAS, 142290, Pushchino, Moscow region ( [email protected])

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

So why is such a mind-boggling, very expensive and dangerous, in case of errors, complexity of splicing needed? And for

A looking for l tsuyuofe b ol T I live e ke R wow on byuu T Ha And about V byuu n tsf th oooops

This "gene" has 12 exons and 12 introns. If you remove all introns one by one in 12 stages, you get the name of a special type of splicing: alternative.

And that's what alternative splicing is all about: some well-defined exons are cut out along with their introns. And then from “aischaltsuyuofeyoltjiuekeruyunabyuthaiprovbyuuntsfyoooops” it will turn out:

alternative+ searching+tsuyuofe+ol+jiukeuyu+byu+ha+pro+byu+btsf+ooops
alto+ looking for+tsuyuofe+ol+zhiuek
native+ aischaltsuyuofeyoltjiuekeruyu+byu+ha+pro+byu+btsf+ooops
naive+ aischaltsuyuofeyoltjiuekeruyu+buutha+pro+byu+btsf+ooops
left+ aischa+tsuyuofeyoltjiu+keruyunabuuthaipro+byuncf+ooops
a lion+aischa+tsuyuofeyoltjiu+keruyunabuuthaipro+byuncfiyoops

As a result, from one seemingly meaningless word, six quite meaningful ones were obtained. What if this word is a gene?

Indeed, the pathway for joining exons belonging to one gene can be multiple. Some exons may be removed along with introns. This alternative splicing results in the same gene being able to encode a family of structurally similar but functionally different proteins. Currently, the maximum known number of different proteins that a single gene can encode is about 40,000! (Suma in cuirsive - forty thousand). For example, the Drosophila gene, which encodes one of the axon receptor proteins, can result in the formation of 38,016 different messenger RNAs through alternative splicing. This gene contains 95 alternative exons. But are all genes expressed through alternative splicing? According to current knowledge, at least 74% of human genes operate through alternative splicing! (9.10).

Now is the time to ask the question: what is a gene?
A gene (eukaryotic) is a long and predominantly random, non-coding sequence of nucleotides in which regions (exons) are located that, after being excised from the transcript of this gene and combined in a strictly defined order, can encode a specific function.

We especially note that with alternative splicing the order of exons is not disrupted. In the final spliced ​​RNA, some exons may or may not be present, but their positions do not change. For example, in terminally spliced ​​RNA, exons 1-2-3-4-5-6 may be, for example, in the sequence 2-4-6, but not in the sequences 4-2-6 or 6-4-2. Thus, from the same gene transcript, using different variants of recognition, excision and joining of different exons, it is possible to obtain many different protein isoforms that will have some amino acid sequences in common, but which will differ in their functional properties. And what was at first naively believed to be meaningless - the mosaic structure of genes - in fact turned out to be a very effective and economical way to encode many meanings through a limited number of characters. True, this led to a significant complication of the rules for detecting these meanings. The alternative splicing pathway is largely determined by the regulatory signals of the cell that characterize its state. In response to a change in the physiological situation, different functions are realized from the same gene.

It is very important that with the evolutionary complexity of organisms, the average number of introns per gene increases. As organisms become more complex, not only the number of introns increases, but also their length. And genome size correlates with the total length of introns contained in the genes of a given species; Invertebrate introns are shorter than human gene introns, and yeast introns are shorter than invertebrate introns. In general, in a gene, the total length of introns can exceed the total length of exons by tens and hundreds of times.

If sequencing (determining the nucleotide sequence, sequence) of eukaryotic genes led to the stunning discovery of their mosaic structure, then mass sequencing of entire genomes of different organisms led to simply amazing results. In mice, humans, and fugu fish (ball fish), the number of genes is almost the same - 30,000-40,000. What then determines evolutionary complexity?

Moreover, if we compare the coding sequences (exons) in the mouse and human genomes, it turns out that they are 99% identical! Why are we so different from mice? A?

It may also be because, despite the fact that our genes are similar to mouse genes, our alternative splicing occurs either along different paths, or is more multiple. Or both at the same time. It’s not for nothing that, as evolution progresses, the average number of introns (and therefore exons) per gene increases? After all, this expands the range of proteins potentially encoded by one gene. And as a result, due to different alternative splicing, almost the same genes produce either a mouse, or a baboon, or the one (or the one) who is currently reading these lines.

Alternative splicing provides evolution with virtually limitless possibilities. The material of evolution is genetic diversity, and the engine is natural selection. But alternative splicing leads to such a diversity of proteins that... Judge for yourself. A combination of only three genes, each of which can encode only 1000 protein variants, gives 100,000,000 possibilities for natural selection (1 billion isoforms of three proteins). What if there are 1000 such genes? What if 10,000?

What was the mechanism for the emergence of mosaic genes and alternative splicing pathways? It seems that ancient self-replicating molecules (or their aggregates, or ancient cells) contained: firstly, a “random number generator”, a mechanism that synthesized extended random sequences of nucleotides, and, secondly, a mechanism that cut these sequences into random ones fragments and, in different combinations, connecting these fragments. And then natural selection evaluated the result. If the result of connecting fragments improved self-reproduction, such a mosaic gene and its alternative splicing pathways were preserved; if not, not.

And the most striking thing is that point mutations in an exon can lead to a change in the splicing path, in other words, a change in a letter in a syllable can lead to a change in the way it is connected to other syllables. Random point mutational variability leads to variability at a higher level - to variability in the path of combining subsemantic blocks. Of course, this greatly speeds up evolution (11).
But it ruins genomic companies.

“Your lady was killed,” Chekalinsky said affectionately.
Hermann shuddered; in fact, instead of an ace, he had a queen of spades.
He couldn’t believe his eyes, not understanding how he could have gotten so naked.
Pushkin

The Human Genome Project - sequencing the genome of Homo sapiens - in its scientific significance and ambition is compared to the program of manned flights to the Moon. The cost of these programs is comparable. Billions of dollars. But the initiators of the Human Genome Project, in addition to scientific goals, also had grandiose plans for the practical use of genetic information that should be obtained as a result of its implementation. And where there is practical use, there is commercial interest. It was assumed that information about the human genome would be useful for early molecular diagnosis of hereditary diseases and for their treatment through replacement genetic therapy (a defective gene is replaced with a normal one). It was planned that information about human genes would lead to the development of a new generation of drugs created on the basis of knowledge about the dysfunction of certain proteins. If we know how a defective protein that leads to a disease is encoded and expressed, it will be possible to create molecules that will specifically correct pathological processes at the molecular level. And this, as predicted, could bring billions in profits. But first, multimillion-dollar investments were needed. And they were done. Firms were created that sequenced the human genome. Nucleotide sequence information that was believed to lead to the development of new diagnostic and therapeutic methods was patented.

But does the nucleotide sequence of a eukaryotic gene provide unambiguous information about which protein it encodes? No. Determinism is impossible here! It all depends on the alternative splicing pathway. And there can be tens of thousands of these pathways for one gene. Isolating and characterizing tens of thousands of proteins and establishing which isoform is responsible for the pathology is an almost impossible task. At least for now. And the famous human genome decipherer Craig Venter is leaving his post as director of the genomics firm Celera Genomics and changing the direction of his business. Now he is deciphering the genomes of bacteria. His scientific ship plows the waves of the Sargasso Sea (in the Bermuda Triangle area), the crew catches marine microbes and sequences their genomes right on the ship. The total length of all already sequenced nucleotide sequences is more than 1 billion nucleotides; it relates to 1,800 species of bacteria, of which 148 species were previously unknown. The goal of the project is to search for new genes of practical importance. Of course, working with prokaryotic genes is incomparably simpler: one gene - one protein. (Microbes “went a different way”). While Craig Venter has already resigned, the director of the genome firm Human Genome Science, William Haseltine, has only announced that he is going to “move on to another job” (12).

So, the path of progressive evolution is directed
- from simple reproduction of ribozymes, increasing their number, to increasing their length due to duplications and divergence of duplicated genes due to subfunctionalization.
- from random enumeration of nucleotides, to random enumeration of exons encoding subsense modules and to enumeration of their alternative splicing pathways.

It is important that randomly formed duplications undergo a random mutation process that affects the initially identical functions of both genes. And the action of selection aimed at maintaining the original common function leads to divergence of the functions of duplicated genes. This leads to the fact that if before duplication a certain function was performed by one gene, then after duplication and the mutation process two genes can perform this function and only together, but not separately. And all this leads to a very important and new conclusion for the theory of evolution: progressive divergent evolution occurs without changing environmental conditions as a result of constantly ongoing random mutation processes, in which the main role is played by spontaneous duplications of genes (and genomes). The selection that acts in this case is neither directing nor destructive, but stabilizing (cleansing harmful mutations). Progressive evolution, accompanied by complication, does not have adaptive(in relation to the environment) character. This very unexpected and fundamental position was formulated quite recently (13).

Of course, such a “progressive” complication must be “compatible with life”; we will never know about those cases when it was lethal. And, of course, after such “complication”, directive or disruptive selection adjusts (adapts) organisms to specific environmental conditions.
When we discussed the structure of the eukaryotic gene, we talked about “nonsense introns.” Let us ask a more general question, however: what is the evolutionary meaning of nonsense DNA?

And life, as you look around with cold attention,
Such an empty and stupid joke.
Lermontov

The most disconcerting joke that evolution has played on humans is the amount of genetic information that an amoeba has. For a single-celled amoeba has 200 times more DNA than the “crown” of evolution. An amoeba has about 600 billion nucleotides in its DNA, while we have 3 billion. Why does it need so many? And what does it say? And several “meaningless words” are written there (millions of times!). And from a modern point of view they mean nothing. Indeed, 99% of the human genome does not encode proteins; these non-coding sequences are represented not only by introns and intergenic regions, but mainly by various types of repeatedly repeated sequences of approximately 10, 100, 1000 or more nucleotides in length. These repeats (present in all eukaryotes) can be located continuously one after another (tandem, localized), or scattered throughout the genome individually (dispersed). According to the mechanisms of origin, these repeats are divided into so-called. satellite DNA (which can be formed due to certain replication errors), etc. retroposons, which are formed due to reverse transcription errors when DNA synthesis occurs accidentally on an RNA template. That's how it happens.

Reverse transcription - the synthesis of DNA on an RNA template - usually occurs during the reproduction of retroviruses whose genome consists of RNA. For the full life cycle of a retrovirus, DNA must be synthesized on its RNA matrix, which is then integrated into the cell genome. DNA synthesis on an RNA template is carried out by an enzyme - reverse transcriptase. But, as you know, no one is perfect (which translated into Russian means: “even an old lady can get screwed” :). It is precisely this prorush that plays the most important role in progressive evolution. Retroviral reverse transcriptase mistakenly begins to synthesize DNA not from viral RNA, but from cellular mRNA. On the one that “comes to hand.” And after a massive increase in the number of copies of this randomly formed “senseless gene”, they are randomly inserted into random parts of the genome.

The disconcerting fact that there is no relationship between the amount of DNA contained in an organism's genome and its evolutionary complexity has been called the “DNA content paradox” - “C-value paradox”, from C - Content (16). Attempts to explain it force us either to abandon the intuitive idea of ​​​​the “reasonableness of the structure of living things”, or to assume that there is a dimension unknown to us in genetic mechanisms. That in fact we see only the external mechanisms of life that are accessible to our primitive mind. But the successes of genetic engineering in creating completely viable transgenic organisms seem to confirm that we more or less correctly understand how genes and genomes are structured and how they work.

Although, in fairness, we note that recently there is evidence that meaningless DNA can sometimes have some meaning. For example, there are cases when a repeating element located inside an intron contains nucleotide sequences that change the path of exon joining and, thereby, create a new protein, i.e. new feature.

Many facts indicate that many RNA molecules, which are copies of “nonsense DNA,” have a regulatory role - they control the operation of genes, in particular during the development of organisms (during cell differentiation). Recently, evidence has emerged that some changes in “nonsense DNA” lead to the so-called. epigenetic effects, i.e. to modification of gene function, not accompanied by a change in their nucleotide sequence (17).

But at the moment we can say with confidence that only 1 to 10% of eukaryotic DNA has a meaning that we understand. The rest of the DNA, apparently, firstly, does not have significant functions and, secondly, does not violate (at least significantly) the viability of the organism. It is "meaningless", but not fatal. And thirdly, paradoxically, it is “selfish and meaningless” DNA that significantly predetermines the paths of “progressive” evolutionary changes.

If only you knew what kind of rubbish
Poems grow without shame
Akhmatova.

Could it be that changes in “nonsense DNA” guide the evolution of life? What then is the meaning of Life?

In a random outbreak of mass production of “nonsense DNA” (satellite DNA and/or retroposons), such a radical change in the genome occurs that it leads, if not to death, then to the formation of a new biological species. The main characteristic of a biological species is reproductive isolation, the ability to interbreed productively only with individuals of its own species and the inability to produce fertile offspring when crossing (if it does occur) with representatives of other species. One of the mechanisms of reproductive isolation is based on the absence of a high level of similarity (homology) between the genomes (chromosomes) of crossing individuals. When a fertilized zygote is formed, pairs of chromosomes, each of which originally belonged to one of the parents, must be homologous and capable of recombination (exchanging sections of DNA with each other). If this is not the case, for example, due to the fact that large block rearrangements have occurred in the chromosome (or chromosomes) of the germ cells of one of the parents, normal development of the zygote most often does not occur. But in very rare cases, as a result of genomic rearrangements that have occurred in the zygote, caused by the dissimilarity of the parental chromosomes, viable descendants can still be formed, which can most effectively interbreed only with their brothers and sisters who have similarly rearranged chromosomes. This seems to be how speciation occurs quite often.

The formation of large block genome rearrangements caused by the massive production of repeated DNA sequences is sometimes called genome formatting. Closely related species almost do not differ from each other in “sense” coding regions of DNA, but they differ very much in “non-sense” ones, in repeats. Only organisms with genomes of the same format can interbreed. A format in which identical repeating sections of egoistic DNA are located in identical places on the parent chromosomes. And evolution, figuratively speaking, is a reformatting of genomes compatible with life due to random changes in the quality, quantity and location of sections of nonsense DNA. Natural selection then first removes non-viable variants, and adapts the surviving reformatted ones to a more efficient existence in specific environmental conditions.

But in general it seems that evolution is a process:
- random gene duplications, leading due to the occurrence of mutations to their subfunctionalization, i.e. to the differentiation of their functions and, ultimately, to complication,
- random mass production of non-coding ("senseless") DNA, leading to speciation, and
- natural selection, which removes non-viable forms and favors viable ones.

And the meaning of evolution is that it occurs due to random small changes in semantic information aimed at maintaining its coexistence with an increasing amount of meaningless “information.”
Now let's summarize.

I am convinced that He does not play dice...
Einstein.

Life is information, the meaning of which is to ensure the self-reproduction of its carrier and, thereby, distribution through the absorption of matter and energy. It arose (or was reborn) from the cooled ashes of the Big Bang that created the Cosmos. And under the destructive effect of Chaos of random processes, life began to evolve in order to preserve its meaning. The first “word” (the first living information molecule) began to turn into a text of synonyms, the meaning of which was differentiated and became more and more specific, but together they convey the same meaning from generation to generation.

He doesn't really play dice.
He sends a message - a self-transmitting and self-propagating message, evolving to overcome interference.
Which is Life.

Literature:

9. Kolkman JA, Stemmer WP. Directed evolution of proteins by exon shuffling Nat Biotechnol 2001;19(5): 423-428.
10. Modrek B, Lee C, A Genomic View of Alternative Splicing. Nature Genetics, 2002, 30, 13-19.
11. Cartegni L, Chew SL, Krainer AR. Listening to Silence and Understanding Nonsense: Exonic Mutaions that Affect Splicing. Nature Reviews, 2002, 3, 285-298.
12. Silverman P H, Rethinking Genetic Determinism: With only 30,000 genes, what is it that makes humans human? The Scientist, 2004, v.18, N10.
13. Lynch M, Conery JS. The Origins of Genome Complexity. Science, 2003, 302, N5649, 1401-1404.
14. Hurst GD, Werren JH. The role of selfish genetic elements in eukaryotic evolution. Nat Rev Genet. 2001; 2(8):597-606.
15. Kidwell MG. Transposable elements and the evolution of genome size in eukaryotes. Genetica. 2002, 115(1):49-63.
16. Gregory TR. Coincidence, coevolution, or causation? DNA content, cell size, and the C-value enigma. Biol Rev Camb Philos Soc 2001; 76(1):65-101.
17. Mattick J S. Challenging the dogma: the hidden layer of non-protein-coding RNAs in complex organisms. BioEssays 2003, 25:930-939.

The presence of evolutionary progress in living nature is beyond doubt, primarily due to the presence of paleontological data showing that in real evolution, more and more advanced animals appeared. Figure 5, for example, shows data on the time of appearance of different classes of vertebrate animals in the process of evolution (Carroll, 1992). As can be seen from this figure, skullless fish appeared in the Cambrian, cartilaginous and bony fish - in the Silurian, amphibians - in the Devonian, reptiles - in the Carboniferous, mammals - in the Triassic and birds - in the Jurassic. The time when more and more advanced animals appeared on Earth was separated by millions of years, so progressive evolution, in any case

In the case of mammals, it did not go so quickly, although its direction is obvious (Fig. 5).

Most Russian authors believe that progressive evolution is equivalent to the concept of morpho-physiological progress - arogenesis. It would seem that after clarifying the concept of progress, domestic evolutionists would have to explore the possible mechanisms of this grandiose process. But this did not happen, apparently as a result of pressure from the authorities of the founders of the theory of natural selection, who believed that the direction of evolutionary processes does not exist and there is no need to highlight the mechanisms of macroevolution in any way. And yet, the evidence for the direction of many evolutionary changes and especially progressive evolution (Fig. 5) is so obvious that Darwinists were forced to look for explanations for these phenomena.

It is usually believed that the direction of evolution of individual groups of animals and plants is associated with the presence of a number of restrictions that determine this direction. A.S.Severtsov (1990), for example, identifies the following factors that limit the possibilities of evolution of a particular group of organisms: 1) physical and chemical laws; 2) morphological features of the structure of organisms; 3) restrictions imposed by ontogeny; 4) environmental restrictions.

It is obvious that such limiting factors cannot explain the fact of progressive evolution of animals and plants. Therefore, many scientists generally deny the presence of directionality in organic evolution and do not distinguish morpho-physiological progress from other evolutionary changes in organisms, believing that in this case the same patterns apply as during speciation or the emergence of the appropriate structure and behavior of organisms. In fact, this kind of explanation of real processes occurring in living nature is an attempt to get away from

solution to the problem, which is the reason for the persistence of Lamarckian theories of progressive evolution.

The essence of Lamarck's (1937) ideas regarding progressive evolution was the assertion that there is a special law of self-improvement specific to living organisms (the principle of gradation), which leads to a gradual complication of their organization. The statement about a special force or law acting in the direction of increasing the degree of perfection of organisms in the process of progressive evolution underlies most neo-Lamarckian theories (Zavadsky, 1973; Filipchenko, 1977; Nazarov, 1984). This kind of theory cannot satisfy most scientists, since the presence of special laws or forces requires, as is customary in science, special evidence. It is possible, of course, to introduce statements of this kind as postulates or axioms, but in this case, consequences that can be verified must be indicated. There is also the so-called principle of complementarity, which states that new principles or theories should not contradict old, firmly established truths, but only complement and generalize them. As shown above, the theory of natural selection cannot be refuted, since it is based on obvious axioms, therefore any theory of macroevolution, and, especially, the theory of progressive evolution, must contain natural selection at some stage.

Chapter 1. Theories of progressive evolution

Who knows that the spirit of man rises high,

And the spirit of cattle - does it go down into the ground?

Ecclesiastes, III, 21*

Everyday anthropocentrism

A person can remain indifferent to many things, but not to his own person. He is interested in literally everything about himself: appearance, psyche, mental abilities and especially origin. Traits of parents and more distant ancestors are usually sought out and valued. All peoples have an idea of ​​the nobility of their ancestors, in other words, their cult exists in one form or another. Sometimes, unfortunately, this cult takes the form of nationalism, and representatives of different nations are ready to do anything just to prove the superiority of their ancestors, and thereby their exclusivity.

It’s funny that nature’s inherent desire for self-praise forces us to distinguish our species from the rest of the animal world and place it on the highest level. Agree that the name itself Homo sapiens, that is, a reasonable person already “sounds proud.” Touched by our specific characteristics, we are often inclined to deny our kinship with other animals, tracing our origin from some deity or, as is now fashionable, from aliens from other (extraterrestrial) worlds.

The obvious resemblance to animals often even hurts our pride. Thus, in the book of Charles Darwin (1809–1882) “The Descent of Man and Sexual Selection,” one explanation is given for why some African tribes knock out their fangs and paint their teeth blue. It turns out they don't want to be like dogs. However, under the pressure of irrefutable evidence, having difficulty recognizing our kinship with other animals and agreeing to be included in the same group with monkeys, we gave it the very immodest name “primates,” which means “first.” Apparently, this name itself was supposed to “scientifically” attest that people belong to the most perfect animals. Apes - anthropoids - are especially close to us. Thus, humans and chimpanzees share at least 99% of their genes. We do not have a single organ, not a single structure that anthropoids do not have (right down to the appendix). Such striking similarities force us to place these monkeys above the rest and call them great apes.

Let's try to look at the higher primates from the outside, forgetting for a while about our obvious kinship with them. We will discover that there are only a few species of these monkeys currently living on Earth, leading a very secretive lifestyle in the tropical forests of Africa and Asia. Their populations are quite low, and for species such as the orangutan and mountain gorilla, even close to the dangerous point of extinction. Despite the fact that many similarities can be noted in the lifestyle and behavior of apes and humans, they apparently do not possess the main source of our pride - abstract thinking - and if they do, they clearly do not use it. Therefore, while we are amazed at their similarity to us, we cannot prove why, for example, a gorilla should be considered more perfect than a leopard, a buffalo, or, finally, any beetle.

Moreover, speaking about the greatness of our animal ancestors, we must not forget about other representatives of our kind Homo. Where are they? According to paleontologists, this genus never shone with an abundance of species, but still once existed H. habilis(skillful person) and numerous representatives H.erectus(homo erectus). More recently (about 50 thousand years ago), a species close to us (or maybe even a subspecies) lived on Earth - the Neanderthal (Homo sapiens neanderthalensis). By the way, he was not inferior to us in terms of brain size, and the features of the burials clearly indicate his ability for abstract thinking. And yet, the Neanderthal died out, apparently unable to withstand the struggle for existence. Of course, one can fantasize about the immediate causes of this event; for example, one can imagine that it was our species that was responsible for the death of the Neanderthals, or that we simply absorbed them during mestizization (interracial hybridization).

Finally, let’s remember our very recent past. What was N. sapiens just some 15 thousand years ago? Small groups (20–30 people each) of nomadic hunter-gatherers, lost in vast expanses of virgin forests, do not give the impression of brave conquerors of nature. Take a closer look at the aborigines of Australia or the Amazon, listen to their myths and legends and you will notice with what respect and downright reverence they treat not only large mammals - the main objects of their hunt, but even very small animals, birds and reptiles. And our fairy tales and beliefs abound in the mutual transformations of humans, animals and plants into each other. The man in these stories appears to us not as a proud giant, but as a humble petitioner to the spirits for good luck in the very unreliable business of hunting.

The situation changed dramatically with the advent of agriculture and cattle breeding. Control over the breeding of certain species of animals and plants gave man the opportunity to feel his superiority over them. The new view of nature is reflected in the Old Testament, where God says to the newly created people: “Have dominion over the fish of the sea, and over the wild animals, and over the birds of the air, and over every livestock, and over all the earth, and over every living thing that moves. on the ground". Thus, our everyday anthropocentrism is no more than 8-10 thousand years old.

The further course of history was accompanied by continuous technical progress, the basis of which was not at all the desire for the common good, but the much more prosaic so-called prestige economy. Representatives of the human race for the most part strived and strive not so much to satisfy their needs for food, shelter, etc., but to a higher position on the social ladder. The main “objective” arguments in human society are usually proximity to “aristocratic” families and so-called wealth. Our sporting, competitive spirit, completely justified in primitive times, now prevents us from getting rid of such vices as materialism, nationalism and... anthropocentrism.

High and low

Any modern educated person, of course, knows that the world of living organisms around him is a product of a natural process - evolution. He also knows that the theory of evolution was created by Charles Darwin. It follows from it that each subsequent generation is adapted to life a little better than the previous one, that is, it is in some sense more perfect. As a result, in the course of evolution there should be continuous improvement of all forms of life.

Rice. 1. Historical development of the animal kingdom (based on: [World of Wildlife, 1984]).

As we know from the school curriculum, fish appeared on our planet somewhere in the Ordovician (see table and Fig. 1), then in the Devonian-Carboniferous, amphibians branched off from them and began to colonize land. Amphibians gave birth to reptiles, and during the Mesozoic era they were embodied in a huge number of forms, among which dinosaurs are always remembered. Then dinosaurs, and with them other monsters (pterodactyls, ichthyosaurs, etc.) became extinct at the end of the Cretaceous period, giving way to more advanced birds and mammals. The latter, rapidly improving, gave birth to higher primates. Finally, about 15 million years ago, the first representatives of the family Hominidae appeared. The evolution of hominids proceeded under the sign of an increase in the brain, improvement of speech and tools. The stages quickly flashed by: Ramapithecus, Australopithecus, Homo Able, Homo erectus (Pithecanthropus, Sinanthropus, Heidelberg Man), Neanderthal and, finally, our species (or subspecies) - Cro-Magnon. Hooray! We defeated everyone because we were the ones who completed this terrible race. Our excellence is deserved and beyond doubt.

Geochronological scale

Note. Dominant forms are in italics.

However, let's look around us. At the moment, at least two million species of animals live on Earth, from a biological point of view the same entities as us. It turns out that two million more species completed the evolutionary competition with us. Each of them had its own ancestor species: it turns out that behind each species there is a long chain of ancestors that stretched for at least two billion years. But if fish are inferior, that is, less perfect, then why didn’t they become extinct, and why are there at least 20 thousand species living in the seas and fresh water bodies? Why did not all reptiles become extinct? Even after the terrible catastrophes that struck the Earth at the end of the Cretaceous period, modern reptiles are not inferior to mammals in the number of species. If we assume that surviving reptiles are more advanced than extinct ones, then we will have to admit that snakes and lizards are higher in level of organization than dinosaurs, ichthyo- and plesiosaurs. Not a single zoologist would agree with this. We have already mentioned the pitiful species numbers of great apes. And finally, the main absurdity! Most of the animal species are invertebrates, of which insects come first. Some families of beetles or butterflies contain more species than the chordate phylum with all vertebrates (Fig. 2).

Rice. 2. The ratio of the number of species in various systematic groups of modern fauna (according to: [Ross et al., 1985]).

Thus, if we take an objective point of view, it turns out that insects turned out to be the winners in the competition for life, and the textbook sequence: fish - amphibians - reptiles - birds - mammals - humans is just a sequence of the appearance of new forms. The fact that the land was developed not by fish, but by amphibians and reptiles, is quite trivial. The new, existing next to the old, may not be better, but simply different. Thus, we see that the straightforward approach, in which perfection is associated with victory in the struggle for existence, seems to lead to a paradox.

But excuse me, isn’t it obvious that fish are inferior to animals and birds in terms of internal organization? Isn’t it obvious that ciliates and amoebas are simpler than any worm, and lower plants like mosses are much more primitive than palm trees and eucalyptus? Indeed, shouldn’t we listen to the opinion of the sages who lived before Charles Darwin, when the magic words “natural selection” and “struggle for existence” had not yet been uttered?

The idea of ​​varying degrees of perfection of living organisms inhabiting the Earth rests primarily on our anthropocentrism. On the one hand, we recognize ourselves as part of the animal world, and on the other hand, we clearly identify the “gap” that separates humans from other animals. Our fundamental difference is not that we are hairless, walk on two limbs and make articulate sounds, but that we are capable of abstract thinking. This ability allows people to plan their actions, subordinating them to clearly understood goals. True, this forces us, when considering any process occurring in nature, to ask questions: For what? For what purpose? These questions are good for understanding the reasons for other people's actions, but are they legitimate in many other cases? For example, the question: “Why does the sun shine?” will most likely make the reader smile, because the glow of the sun has no purpose, and yet quite recently this question was answered: “So that we can be light and warm.” Even such a universally recognized sage of all times as Aristotle (384-322 BC), believed that in nature everything “exists for the sake of something or must correspond to what exists for the sake of something.”

Considering human goal-setting activity to be the highest form of behavior of living beings, Aristotle was the first to divide them according to the degree of perfection. Below all of them he placed plants with their plant soul, that is, the ability to grow and reproduce. Somewhat higher were placed “lower” sedentary animals that are capable of feeling only through contact (i.e., they have a sense of touch, taste). A higher level was occupied by mobile animals, capable of perceiving signals from the surrounding world also at a distance using vision, hearing and smell. Their aspirations are not based on reason, but they are capable of imagination. The only animal that was placed on the highest level was man, who in addition to imagination also has reason.

The ascending series of beings was built by Aristotle in accordance with the complexity of their soul. All members of the series have a plant soul, the “higher” animals are endowed with all the properties of the soul of the “lower” ones, and man has the most complex soul. Everything seems to be logical, although the words “higher” and “lower” themselves cause some dissatisfaction. Even if the soul of the higher ones consists of a greater number of components, “more” does not mean “higher.”

Perhaps the reason for identifying complication with improvement lies in the uniqueness of our social life. Note that with us, whoever commands is the one above. After all, we are talking about representatives of power - “the top”. Any person, even at the lowest level of the social ladder, can command domestic animals, which means he is above them. Having assumed that the higher position of people in comparison with other mobile animals is associated with the increased complexity of the human soul, Aristotle continued the descending series to the lower animals and plants.

Aristotle does not explain how this ladder of living forms appeared in nature, although, taking into account the peculiarities of his philosophy, it can be assumed that it was based on the so-called final causes - goal factors. Under their influence, matter constantly strives to be embodied in more complex and more harmonious forms. This idea of ​​nature's striving for complex organization became an integral element of most philosophies of subsequent centuries.

Scientific anthropocentrism

The anthropocentric principle of classifying living organisms has been preserved for two millennia. Even J.-B. Lamarck (1744–1829), the creator of the first evolutionary theory, we read: “It can be recognized as a completely reliable fact and obvious truth that of all species of animals it is the human organization that is the most complex and the most perfect, both in general and in relation to those abilities , with which she endows him,” and further - “it can be argued that the more the organization of an animal approaches the organization of man, the more complex it is and the greater perfection it has achieved, and vice versa: the further a given organization is from man, the simpler it is and the less perfect."

Lamarck's evolutionary theory suggests that the filling of the steps of the ladder of living beings (gradation) proceeded gradually from bottom to top under the influence of a special “force of nature.” This mysterious force was impeded by some "modifying cause" that violated the strict observance of the principle of gradation. Note that Lamarck equates complication with improvement, therefore, in his opinion, living beings in the process of evolution change from simpler to more complex and at the same time from more primitive to more perfect. According to his ideas, the most primitive and simple ones arise from inanimate nature through spontaneous generation.

We see that Lamarck's evolutionary theory is not very helpful in answering the question of how we divide living organisms according to the degree of perfection. Similarity to humans, even ignoring the artificiality of this criterion, is difficult to use when assessing the degree of perfection of invertebrates - they are all equally far from humans. It is interesting that, despite all the illogicality of anthropocentrism, it continues to live even among modern anthropologists. Thus, J. Jelinek in the “Large Illustrated Atlas of Primitive Man” writes: “Man, or scientifically Homo sapiens, the most perfect of all living beings."

Strange as it may seem, the greatest contribution to the objective substantiation of the ladder of creatures was made by the ardent opponent of the evolutionary idea, the famous J. Cuvier (1769–1832). He wanted to build a classification of animals only on facts, while trying to find a sign that was most characteristic of a given kingdom of living beings. Such a feature, according to Cuvier, is the structure of the nervous system, which “... essentially is the whole animal; other systems exist only to support and serve it.” Accordingly, all animals are divided into four types - vertebrates, mollusks, articulated and radiated. In fact, Cuvier materialized what Aristotle considered the soul. Having chosen the sign that supposedly best conveys the essence of the animal organism, he, exactly following the great Greek, sees it in the development of the psyche and motor activity.

With all due respect to Cuvier, it is difficult to agree with the division of organs into more and less important. After all, it is well known that all systems of the body are equally necessary to maintain its life. Damage to both the brain and the heart, kidneys, and intestines equally “reliably” lead to illness and death. And Cuvier himself believed that “each organism forms a single closed whole,” and “that if any of the functions of the body are changed out of compliance with the change in other functions of the body, then it will not be able to exist.”

One cannot but agree that the nervous system makes a great contribution to the integration of the body, but in this it is hardly inferior to, for example, the circulatory system, and we are not able to understand which of them is more important for animals. Is the contribution of the kidneys to the integrity of the body less? It seems that the nervous system is chosen as an “objective” criterion only because the brain reaches its maximum development in humans. Thus, the choice of the height of organization of the complexity of the soul or the type of nervous system as a criterion is equally determined by anthropocentrism.

Darwin's idea of ​​natural selection is based on the idea of ​​differences in the fitness of individuals competing with each other. “Survival of the fittest” should not automatically mean survival of the more complex, or even more progressive. In this regard, it is not surprising that one of Darwin’s closest associates, T. Huxley (1825–1895), was very skeptical about the very idea of ​​evolutionary progress. He was especially impressed by the so-called “persistent forms,” i.e., species or genera that have remained virtually unchanged over tens or even hundreds of millions of years. These forms are quite common among mollusks, crustaceans, echinoderms and brachiopods. Suffice it to remember the shield Triops- a phyllopod crustacean that retained its generic (and perhaps species) affiliation for more than 200 million years.

T. Huxley believed that all modern organisms are equally well adapted to their environment, and the division into higher and lower cannot be considered scientific. The attitude of Charles Darwin himself to this problem is reflected in a fragment of his letter to J. Hooker dated December 30, 1858: “... I don’t think that anyone has a clear idea of ​​​​what is meant by ‘highest’...”. Most modern Darwinists generally consider the division into “higher” and “lower” to be an anachronism and use the word “progressive” very loosely. Thus, one of the creators of the synthetic theory of evolution, J. Simpson, calls a taxon more progressive, simply if it arose later in evolution. Another major American evolutionist, W. Grant, uses the term “progressive” in approximately the same way.

It is interesting that T. Huxley's grandson J. Huxley turned out to be a zealous supporter of the idea of ​​evolutionary progress and revived it among Darwinists. J. Huxley drew the attention of evolutionists to the phenomenon of change of dominant (dominant) forms. As the fossil record tells us, in the Ordovician the sea was dominated by molluscs, trilobites and brachiopods; in the Devonian, fish take the lead; reptiles dominate on land throughout the Mesozoic; the tertiary period is the kingdom of birds and mammals and, finally, in the quaternary period, power over nature passes to man (see table).

J. Huxley tried to find objective criteria for evolutionary progress. In his opinion, this is: 1) increasing metabolic rate; 2) increased care for offspring; 3) increasing the speed of reaction to environmental signals; 4) increasing the ability to control the environment and, most importantly, reducing dependence on it. The fourth point looks very romantic, but it is to this that J. Huxley attaches the greatest importance. The thesis about managing the environment, which is theoretically possible only for humans, sounds especially strange. But what kind of management can we talk about? For now we are only “conquering” nature.

J. Huxley's anthropocentrism is seen even more clearly in his idea of ​​unlimited progress leading to man. Quite traditionally, special attention is paid to the development of the central nervous system as the main means of increasing independence from the environment.

The idea of ​​unlimited progress was developed by the Soviet evolutionist K.M. Zavadsky in his idea of ​​“mainstream progress” leading to man, i.e., Aristotle’s point of view was again confirmed. This was made even more clearly by P. Teilhard de Chardin, a French paleontologist and philosopher, one of the discoverers of Sinanthropus, a man who sought a compromise between science and religion. He wrote: “... rejecting all anthropocentrism and anthropomorphism, I believe that there is a direction (sens) and a line of progress of life so clearly that their reality, as I am convinced, will be generally accepted by tomorrow's science.”

He is looking for an “Ariadne’s thread” leading to a way out of the labyrinth of heterogeneous evolutionary tendencies. As one might expect, this thread for him turned out to be the degree of development of the nervous system and psyche. Having performed this old trick, Teilhard de Chardin exclaims: “As soon as the production of the nervous system is taken as a measure (or parameter) of an evolutionary phenomenon, not only many genera and species are arrayed in a row, but the whole network of their whorls, their strata, their branches rises up like fluttering bouquet. The distribution of animal forms according to the degree of brain development not only coincides exactly with the contours established by taxonomy, but it gives the tree of life a relief, a physiognomy, an impulse, in which one cannot help but see a sign of truth. Such harmony, moreover, unconstrained, invariably constant and expressive, cannot be accidental.”

Of course, one cannot help but admit that in the line leading from fish to higher primates, there was indeed an increase in the relative size of the brain, especially its anterior sections. However, we have no reason to attach special significance to this particular trend. In the series of fish and mammals, in addition to the brain, the heart with the vascular system, kidneys, lungs, and structures for maintaining the stability of the intraorganismal environment underwent progressive enlargement and complexity. But in the same series, one can note a tendency towards a decrease in reproductive potential, which, however, is compensated by the transition to live birth and increased care for offspring.

So, if we discard anthropocentrism, we have no objective grounds to particularly highlight the progressive development of the central nervous system and we should consider it only a special case of a widespread phenomenon - enlargement and complication during the long evolution of some organ or organ system. We will try to provide a rational explanation for this evolutionary trend.

Lamarckism

The first theory explaining the ladder of creatures from an evolutionary perspective was created by the great French biologist J.-B. Lamarck (1744–1829). Lamarck formulated its main provisions in four laws:

"The first law. Life, by its own forces, continually strives to increase the volume of every body endowed by it and to expand the size of its parts to the limit established by itself.

Second law. The formation of a new organ in the body of an animal is the result of a new need that has arisen, which continues to be felt, as well as a new movement generated and supported by this need.

Third law. The development of organs and the power of their action always correspond to the use of these organs.

Fourth law. Everything that has been acquired, imprinted or changed in the organization of individuals during their lives is preserved by reproduction and transmitted to new individuals who experience these changes.”

For Lamarck, the truth of these laws is self-evident. Let's turn to the first law. Don't we observe the growth of an organism during its development? Doesn't this indicate the existence of a special “growth force”? The second and third laws canonize the well-known facts of increasing the efficiency of many organs when exercised. In fact, if a person has a need to run fast, he can significantly improve his athletic performance with the help of training. At the same time, quite adequate, i.e., expedient changes will occur in his skeleton, muscles, respiratory and circulatory systems. Why not assume that in the process of training a person directs his growth force to organs with insufficient function? It turns out that the distribution of growth force in the body is under the control of the psyche. The fact that people (and especially animals) are not fully aware of the details of their own structure does not matter, since it is possible to direct the growth force (in the form of a flow of special material particles - fluids) completely unconsciously.

However, the fourth law is, to put it mildly, puzzling. Where did Lamarck observe its manifestation? Was it really only “folk wisdom”, like that recorded by A.S., that served as the source? Pushkin in his “The Tale of the Dead Princess and the Seven Bogatyrs.” There is a place where the stepmother, indignant at the whiteness of her stepdaughter’s face, exclaims:

“Look, how much she has grown up!

And it’s no wonder that it’s white:

The belly mother sat

Yes, I just looked at the snow!”

Another example of the direct effect of the mother's visual sensation on the appearance of the offspring is given by the Bible. Jacob, in order for the same-colored sheep and goats to produce spotted offspring, put twigs in the watering trough, and the cattle, “when they came to drink, they conceived before the twigs.” At the same time, the visual sensations from the interweaving of twigs in the minds of the mothers were transformed into spots on the skin of lambs and kids.

Apparently, in Lamarck's time the belief in the inheritance of acquired characteristics was widespread. Even the cynical D. Diderot believed that if people’s hands were cut off for many generations, then in the end there would be nothing left to chop. Note that to refute this misconception, the founder of neo-Darwinism A. Weisman cut off the tails of mice for 22 generations, but did not find any changes in the structure of the tail of the descendants.

An additional basis for the fourth law was the idea of ​​the universal harmony of the world, which was very typical for that time. In such a philosophy there is no place for chance, therefore it is impossible to imagine the completely spontaneous emergence of some new purposeful properties. Indeed, if the level of development of an organ ideally matches the needs of the organism, then there must be a mechanism capable of ensuring such compliance in a changing environment. Remaining captive of mechanistic determinism, Lamarck had to look for a solution to the problem in the form of a dynamic law connecting changes in the environment with adequate and hereditarily fixed changes in the organism.

Despite their scientific form, Lamarck's laws could not convince people with strict thinking. Finding no evidence of variation in species over time, they continued to stand firmly on what they believed to be facts, maintaining faith in divine creation. The most prominent authority in biology of that time, Cuvier, having familiarized himself with Lamarck’s main work, “Philosophy of Zoology,” said: “No one considers this philosophy so dangerous that it needs to be refuted.” Apparently, the “danger” did not threaten the idea of ​​​​the immutability of species. Despite the fact that a huge variety of species must somehow have arisen, Cuvier's scientific ethics required that only phenomena accessible to observation be considered. Since cats, dogs, ibises and other animals mummified by the ancient Egyptians several thousand years ago did not differ at all from modern ones, the problem of speciation could be considered unexperimental, that is, unscientific. By the way, many biologists currently have a similar point of view on the problem of the origin of life on Earth. Various theories concerning this problem are usually met with skepticism, as if we are talking about something not entirely serious.

Darwinism

Essentially, Darwin was the first to introduce the concept of chance into biology. For him, the main model of evolutionary shift was the process of human breeding of economically useful forms of plants and animals. Darwin suggested that the main driving factor in this is the selection of individuals that deviate somewhat from the majority in the direction desired by the breeder. These weak “deviations” are often inherited, so long-term selection accumulates them, ultimately causing a significant shift in the properties of the average individual. In his main work, “The Origin of Species by Means of Natural Selection” (1859), he writes: “If selection consisted only in the separation of a distinct variety and its breeding, then this beginning would be so obvious that it would hardly deserve attention; but its significance lies in the enormous results obtained by the accumulation in subsequent generations of differences that are positively invisible to an unaccustomed eye, differences that at least I tried in vain to catch.”

Where does this subtle hereditary variation come from? According to the original version of Darwin's theory, it arises completely spontaneously without any connection with environmental conditions. However, Darwin did not provide direct evidence of this most important position. The random nature of the occurrence of hereditary variability extremely confused him. Therefore, he tried to assure his opponents that this accident was simply a misunderstood pattern, that the nature of hereditary variability was somehow influenced by environment, exercise, etc. At the same time, the success of methodical and unconscious selection in breeding economically valuable forms of plants and animals was clearly testified that without any exercises, without taking into account any mental experiences of the selected individuals, colossal unidirectional shifts in their organization are possible. It is absolutely clear that the breeder does not create special conditions for the appearance of hereditary variability - it arises on its own.

Darwin transferred the idea of ​​spontaneously occurring hereditary variability for any trait to natural populations. By choosing as a trait the fitness of an individual, that is, its chances of leaving adult descendants, Darwin found a way to understand the process of natural selection. A strange, rather gloomy picture opened up: slightly different individuals of the same species compete with each other for the right to represent the features of their structure in the next generation. At the same time, due to limited food resources, most of the descendants hopelessly die.

If the fact of evolution itself, that is, the change of species over time, was accepted quite easily by contemporaries, then with mechanisms the situation was much worse. The idea of ​​evolution was prepared for perception by Lamarck and the German natural philosophers. The idea of ​​natural selection also gained universal acceptance. Only the source of hereditary variability remained unclear. It should be noted that during the time of Charles Darwin and further until the beginning of the 20th century, the idea of ​​heredity as a kind of liquid (usually called blood) prevailed. It was believed that upon fertilization, the properties inherited from both parents are mixed. Now suppose that an individual with a favorable hereditary deviation is crossed with an ordinary, average individual of the same species. Then, in accordance with the “blood theory,” the favorable trait in the descendant will be diluted by half. And when this descendant is crossed with other ordinary individuals, the beneficial property will be diluted four times, etc. It is easy to understand that if favorable hereditary changes occur rarely, then they will inevitably be diluted and disappear in subsequent generations. This argument was put forward by the engineer F. Jenkin, and Darwin was unable to give a satisfactory answer to it.

The “Jenkin nightmare” could only be gotten rid of by a sharp increase in the probability of the occurrence of similar favorable changes. The second difficulty is associated with the uncertain (in direction) nature of variability. According to Darwin's theory, it turned out that favorable changes are always accompanied by unfavorable ones, that is, variability is not adaptive in nature. This position was subject to intense criticism even from the most devout followers of Darwin. For example, the famous German Darwinist E. Haeckel (1834–1919) believed that environmental changes should cause adequate hereditary variability. He proposed reducing the mechanism of evolution to just two factors - heredity and adaptation. He thought of hereditary variability only as a result of the action of the environment (climate, nutrition, etc.). Essentially, this is pure Lamarckism. What, then, was the novelty of Haeckel’s “Darwinism”? Apparently, the fact is that, firstly, adaptations, i.e., favorable hereditary changes, do not occur in all competing individuals, and, secondly, the very magnitude of such favorable changes is small, so they must be saved, accumulated with by natural selection. Thus, the Darwinism of Haeckel, and even Darwin himself (the later one), differs from Lamarckism only in quantitative terms. Indeed, returning to Lamarck’s fourth law, we can note that it is too categorical.

Perhaps another mistake of Darwin’s zealous followers is their tendency to exaggerate (one might say, deify) the “creative” possibilities of selection, which sees everything, evaluates everything, so that not a single hair on the body, not a single nucleotide pair is left without careful verification. This view was to some extent inherent in the founder of the theory: for example, in “The Origin of Species...” he writes: “... natural selection daily and hourly investigates the smallest changes throughout the world, discarding the bad ones, preserving and composing the good ones, working silently and invisibly, wherever and whenever the opportunity presents itself, on the improvement of every organic being...” This weakness of orthodox Darwinism was fully realized and overcome by the greatest modern evolutionist M. Kimura, who supplemented the theory of natural selection with his “theory of neutrality.”

Neo-Darwinism and Neo-Lamarckism

A. Weisman (1834–1914) dealt a crushing blow to Lamarckism. He showed that the cells of the germinal tract in animals very early become separated from the rest of the (somatic) cells of the body. Therefore, no matter how much you exercise a somatic organ, the result of the exercise (even if somehow imprinted by the chromosomes of somatic cells) physically cannot be taken into account by the chromosomes of the germ cells. From this it inexorably followed that (at least for animals) no individual experience of individuals can be inherited. Thus, Weisman revived Darwinism in its form, purified from Lamarckism - neo-Darwinism.

However, at the beginning of the 20th century, both approaches encountered enormous difficulties due to the successes of the new science of genetics. In 1903, the Danish geneticist W. Johansen clearly demonstrated the ineffectiveness of selection in pure bean lines. Such lines consist of individuals with almost identical heredity. Even though the smallest and largest seeds were planted over several generations, the average seed weight in each line remained the same. For neo-Lamarckians, this result meant a complete collapse, since the very significant individual variability of individuals turned out to be non-heritable. For neo-Darwinists, the full problem arose of how hereditary variability arises.

The experience of classical genetics showed that changing genes is a very rare event. This has given rise to the extremely widespread belief that the occurrence of changes favorable to selection is not a matter of simple chance. The temporary contradiction between geneticists and evolutionists, in essence, was the basis for the growth of many very dubious theories that tried to strengthen the position of neo-Lamarckism. The most notorious theory is T.D. Lysenko, who dominated the USSR in the 30-50s. Here is an excerpt from his article “On Heredity and Its Variability.” “In all those cases when an organism finds in the environment the conditions it needs in accordance with its nature, the development of the organism proceeds in the same way as it happened in previous generations of the same breed (of the same heredity) ... In those cases when organisms do not find the necessary they are forced to assimilate the conditions of the external environment, which to one degree or another do not correspond to their nature, the resulting organisms or individual parts of the body of the organism are different from the previous generation... External conditions, being included, assimilated by the living body, become not external conditions, but internal , that is, they become particles of a living body, and for their growth and development they already require the same food, those environmental conditions that they themselves were in the past... Changes in needs, i.e., the heredity of a living body always adequate to the influence of the external environment, if these conditions are assimilated by the living body" (emphasis added - V.B.).

It is absolutely clear that formal genetics (Morganism) and neo-Darwinism (Weismannism) are incompatible with these ideas. Lysenko's theory was discarded, since the further development of genetics led to an understanding of the nature of heredity, and therefore to an understanding of its variability. In the 30-40s, genetics merged with neo-Darwinism, which marks the emergence of the so-called synthetic theory of evolution, capable of providing an acceptable explanation for evolutionary shifts. It turned out that any natural population has a significant reserve of genetic variability, so it is, as it were, prepared for the action of selection in any direction. And finally, we should not forget that evolution is a very slow process, from an everyday point of view. Even the fastest shifts in morphological characters recorded by a paleontologist do not exceed 10–20 millidarwins, and one Darwin corresponds to a change in the value of a character by e once in one million years ( e- the base of natural logarithms is equal to 2.718).

Paleontologist position

Let us immediately note that a paleontologist’s idea of ​​time has its own characteristics. Usually he operates with the so-called geological time, the duration of which is determined by the thickness of the geological layer and the speed of its formation. This speed depends on many factors, but there are methods for converting geological time to astronomical time. It is customary to measure the latter not by the number of generations or years, but by millions of years. From this point of view, simultaneous events can be separated by thousands and even tens of thousands of years.

Observing long-term unidirectional trends, usually associated with an increase and complexity of morphological structures, the paleontologist often comes to the conclusion that these macroevolutionary changes occur on their own under the influence of some internal factors, not in connection, but contrary to environmental changes. The changed external environment only from time to time rejects species that, due to excessive development (or underdevelopment) of certain morphological structures, lose adaptability. Thus, the paleontologist does not deny natural selection at all, but he reserves for it only the role of a sieve, weeding out species represented by short-lived or too highly specialized individuals.

If, according to Darwin, characters change with the gradual accumulation of small favorable deviations, then the paleontologist does not consider variability at the individual level at all, i.e., the so-called creative role of selection is ignored. It should be noted that a paleontologist most often judges a species by the structure of very few, usually poorly preserved specimens, so he is virtually deprived of the opportunity to study the dynamics of microevolutionary shifts. It would seem that the lack of microevolutionary information should not be an argument against the creative role of selection. However, the paleontologist finds arguments that allow him to ignore microevolutionary changes altogether.

Firstly, the experience of field biologists indicates that a shift in morphology does not always follow changes in the environment. Secondly, we should not forget about the existence of persistent forms that do not change their morphology for many tens of millions of years, despite radical changes in the habitat (in any case, its species composition). Finally, in the last decade, the so-called theory of punctuated equilibrium has been widely and vigorously discussed in the literature on evolution.

This theory is based on a very characteristic pattern of occurrence of individuals with similar morphology at different periods of geological time. It turned out that individuals that are morphologically very similar and apparently belong to the same species can be continuously detected for several million years. Then they “disappear” for a short time, after which they begin to appear again (again for several million years), but with a slightly changed appearance, which allows them to be classified as a different species. Thus, the morphology of the species remains virtually unchanged for several million years. This period was called stasis. Species transformation, i.e. a change in morphology, occurs very quickly, from the point of view of a paleontologist - instantly, although this moment can last tens of thousands of years.

It should be noted that such an intermittent ( punctualist) the picture is not always observed. Apparently, no less often, the distribution of individuals in geological time better corresponds to the traditional one, gradualist models, i.e. the change in their morphology occurs gradually - gradually. The punctualist model does not at all contradict Darwinism, since we do not know what changes in the environment took place during the period of stasis and during species transformation. It does not follow from anywhere that the morphology of a species should change with any change in the environment. The latter would only occur if there was an absolute correspondence between the environment and the morphology of the individual. But there is nothing absolute in the world. At the same time, it cannot be said that the above arguments of paleontologists confirm Darwinism. This circumstance purely psychologically justifies their constant attempts to involve special dynamic factors that act independently of environmental changes to explain macroevolutionary trends.

Chapter 2. Three theories of morphogenesis 2.1. Descriptive and experimental research Description of development can be carried out in various ways: the external form of a developing animal or plant can be sketched, photographed or filmed, giving a picture