Basics of Evolution - Korzh O.P. - 2006

Part III. PATHS OF LIFE'S DEVELOPMENT

Chapter 18. Evolution of Lower Organisms

18.4. Viruses and Their Place in the Evolution of Life

It is conceivable that, due to their structural simplicity, Viruses originate from the first self-replicating structures from which the earliest Cells also evolved. However, their ability to reproduce exclusively within a host Cell indicates that they could have emerged only after cells had formed and METABOLISM/28.html">The Genetic Code had stabilized.

"Viruses: What are they or who are they?" is one of the most perplexing questions in biology.

Finding an answer to this question is directly linked to understanding the very essence of life. According to F. Engels, life is the mode of existence of protein bodies, an essential feature of which is the continuous metabolism with the environment. Based on this definition, viruses are non-living structures, as they lack independent Metabolism and Energy Exchange. According to the Cell Theory of Schleiden and Schwann, All living organisms consist of cells, with the simplest forms being unicellular; therefore, viruses should also be considered matter. Proceeding from the five axioms of theoretical biology, one can conclude that:

1. All living organisms represent a unity of phenotype and genotype. In viruses, the genotype is considered to be The sequence of NUCLEIC ACIDS, while the phenotype is the Spatial Organization of macromolecules.

2. The genetic program is formed in a template manner—using the Gene of the previous generation as a template. Viruses utilize only a single type of nucleic acid—either DNA or RNA—which significantly distinguishes the execution of their genetic programs from all other organisms.

3. During transmission from generation to generation, genetic programs change randomly and non-directionally. Despite the specific functioning of their genetic system, viruses are capable of random and non-directional hereditary changes.

4. Random changes in genetic programs are amplified manifold during phenotype formation. Corresponding to changes in The nucleotide sequence, alterations occur in the outer configuration of viral macromolecules.

5. The manifold amplified changes in genetic programs are subject to environmental Selection. Since it has been proven that viruses evolve alongside other organisms (which is practically impossible without the action of natural selection), this proposition can also be considered valid for them.

Based on the foregoing, it can be concluded that viruses exhibit characteristics of both living objects and non-living matter, occupying an intermediate position between Organic compounds and biological cells. Today, scientists have concluded that viruses possess their own distinct evolutionary history, which, if not entirely, is at least largely independent of the Evolution of the organisms in which they replicate.

The question of THE ORIGIN OF viruses is no less complex, and consequently, several hypotheses currently exist:

1) viruses are descendants of Bacteria (the result of profound morphophysiological regression);

2) viruses are rogue cellular Organelles (Ribosomes, chromosome fragments);

3) viruses are descendants of pre-Cellular forms of life from which both cells and modern viruses originated.

According to some researchers, viruses possess an overly unique non-cellular Structure that cannot be derived from a cell. In this regard, the first theory is rejected by certain scientists. The second and third theories are equally unproven, though the second enjoys broader support.

Viruses are intracellular parasites (sometimes referred to as superparasites) that are completely inactive outside the host cell.

Nevertheless, their role in evolution is critically important: firstly, as a damaging factor that intensifies the Struggle for Existence, and secondly, as a mechanism for vertical and horizontal Genetic information exchange between various taxonomic groups of organisms.