Basics of Evolution - Korzh O.P. - 2006

Part I. MICROEVOLUTION

Chapter 4. Mutational Process as an Elementary Evolutionary Factor

4.3. Pitfalls of Reductionism

Reductionism involves investigating a system by breaking it down into its constituent parts, which are then studied individually, while the obtained results are used to build an understanding of how the system Functions as a whole. Alongside universalism (applying uniform approaches to The Study of the entire physical world) and inductivism (extending knowledge about a single object to the entire group under study), the principles of reductionism remain fundamental to the methodological framework of natural sciences.

A strong fascination with reductionism in the 20th century spurred the rapid Selection/4.html">Development of Genetics, biochemistry, and subsequently molecular biology. The active growth of these biological fields fostered theories aimed at solving general biological problems based predominantly on sub-cellular structures—specifically, the Mutational Process—while almost completely excluding other levels of life Organization from their explanations.

“Creative” Mutations. S. Ohno was among the first to pioneer a molecular-genetic approach to studying Evolutionary Processes, placing great emphasis on so-called neutral mutations, particularly duplications of various components of hereditary material. The further development of molecular evolution theory by M. Kimura led to the ESTABLISHMENT OF THE neutrality theory, often referred to as “non-Darwinian evolution.”

The natural foundation for such theories, aside from the neutralization of deleterious mutations through their transition into a heterozygous state, is the selective neutrality of many mutations, primarily point mutations. The degeneracy of METABOLISM/28.html">The Genetic Code means that a single amino acid can be encoded by multiple nucleotide triplets. For instance, the Synthesis of the amino acid Serine is encoded by six different triplets: УЦУ, УЦА, УЦЦ, УЦГ, АГЦ, АГУ (UCU, UCA, UCC, UCG, AGC, AGU). Consequently, replacing one triplet with another among these via point mutations causes no structural Changes in the corresponding protein, as the synthesized amino acid remains unchanged.

Phenomena of this kind at THE MOLECULAR LEVEL are shielded from the action of natural selection. They occur in substantial quantities and at a roughly uniform rate across different organisms. The accumulation of a significant number of such neutral deviations can lead to a quantitative shift into a new quality: through the genetic recombination of such mutations, a novel trait with evolutionary consequences may emerge entirely by chance.

M. Kimura proposed several generalizations regarding molecular evolution:

1) the evolutionary rate of any protein is constant and uniform even across different phyletic lineages;

2) functionally less important molecules or parts thereof evolve faster than important ones;

3) mutational Amino Acid Substitutions that cause minimal disruption to protein Structure and function are the most common;

4) functionally novel genes arise through duplications;

5) the random fixation of neutral mutations during evolution occurs much more frequently than that of advantageous ones.

This theory earned the label “non-Darwinian” because it rejects the leading role of natural selection. While natural selection as an elementary evolutionary factor is not entirely dismissed, the mutational process is deemed primary. In this view, The formation of new traits appears as a gradual accumulation of minor deviations from the original variant that are either neutral or mildly deleterious—meaning that new traits form entirely against the backdrop of the mutational process.

What objections does this theory raise? First, as mentioned earlier, the mutational process is undirected and random. Indeed, its evolutionary role is immense as a supplier of new elementary evolutionary material, but this material arises spontaneously. One might expect that an increased rate of new mutations—driven by the Introduction of artificial mutagens and other human interventions in nature—would accelerate speciation. In reality, we do not observe a surge in The Emergence of new species; instead, a growing number of organisms are becoming endangered or threatened with extinction. Therefore, mutations alone cannot serve as a self-sufficient foundation for the evolutionary process.

Second, as I.I. Schmalhausen pointed out, we cannot categorize a mutation as neutral, beneficial, or harmful independently of the specific Organism's living conditions. Even when we observe no phenotypic changes resulting from genotypic rearrangements (such as point mutations), we cannot state with absolute certainty that these changes are indifferent to their bearers. We may not yet understand the consequences of such rearrangements. As noted previously, the exact same trait can be either beneficial or harmful depending on environmental conditions.

Undoubtedly, theories of this kind add a certain color to evolutionary concepts, but generalizations should be made with considerable caution, keeping in mind that different Levels of biological organization may differ fundamentally from one another.

Furthermore, according to Schwann's Cell Theory, The Cell is still recognized as the smallest unit of life.

The “Selfish” Dawkins. As a pendulum swing in the opposite direction, R. Dawkins developed The Theory of the selfish Gene. In the author's own view, this theory is simply Darwin's theory formulated in a different way: it is a product of orthodox neo-Darwinism.

The core thesis of this theory is that humans, like any other living organisms, are survival machines built by genes. The emphasis is placed on the idea that the hallmark of a successful gene is its uncompromising, ruthless selfishness. Gene selfishness, in turn, gives rise to selfish behavior in the individual. Universal love and the well-being of the species as a whole are considered biologically meaningless concepts.

Survival of the fittest is viewed as a consequence of a more general law: the survival of the most stable. During pre-biological evolution, complex molecules eventually emerge that differ from their predecessors in their ability to replicate, introducing a new type of stability into nature. Modern Living organisms are the survival machines of those very same “replicators” that arose at the dawn of life. Genes are virtually immortal because they are always passed down, in one form or another, from parents to offspring.

In sexually reproducing species, an individual organism is very large in size yet short-lived, which prevents it from being considered a unit of natural selection. From a genetic perspective, individuals or groups of organisms are temporary and unstable formations on an evolutionary timescale.

An individual organism can be considered reasonably discrete as long as it lives, but what a fleeting process that is! Every individual is unique; sexual reproduction is not Replication: no two identical organisms exist in nature. According to Dawkins, evolution is impossible if the only available choice is between organisms, each of which exists in a single copy.

Genes are strong candidates for the primary unit of natural selection due to their potential immortality. Therefore, according to R. Dawkins, the fundamental unit of natural selection is best considered not as a species, population, or individual, but rather as a specific small unit of genetic material—namely, the gene.

Genes also regulate The behavior of their survival machines indirectly by pre-programming them with the necessary instructions. Consequently, genes must possess a capacity akin to foresight. This capacity relies on the prior experience of past generations whose genes have survived and been passed down to modern descendants. One way to solve such challenges is to endow the survival machine with The ability to learn.

One could quote Dawkins at length, but the core essence of his theory, outlined above, fits into practically a single paragraph. There is no need to refute his views, as these "ideas" speak for themselves. The greatest indignation and misunderstanding stem from his extreme reductionism and the attribution not just of living organism properties, but even of motivations, to individual molecules, driving specific behavioral patterns in the latter. This is despite the fact that a vast number of organisms (for instance, all plants) are still denied the capacity for behavior altogether.

Food for Thought

The reality of the mutation process is beyond doubt. Some discrepancies arise in the interpretation of its evolutionary significance. It is clear that Variability is an inherent property of nature, one that intensifies over time. But should we expect a "super-mutation" in humans that would solve all current problems? Even if this were to occur against a backdrop of absolute selfishness, given that some scientists view altruism as a form of societal selfishness.

Evidently, it is easier to live by fairy tales of a "mutation of justice" that will create a "kind and just ruler," or to assume that genes will make history anyway since at least a small fraction of them will persist in descendants. Yet, should we entrust our destiny to mere molecules, or even to the entire hereditary material? Perhaps we should try to do at least something ourselves—if only for the sake of self-fulfillment.