Basics of Evolution - Korzh O.P. - 2006

Part II. MACROEVOLUTION

Chapter 14. Progressive Evolution

14.1. Problems Related to the Definition of Progress

Real, existing progressive changes in Living organisms are already evident at the earliest hierarchical steps of living beings. One of the first to raise Structure/149.html">The problem of progressive development was J.B. Lamarck, who believed that living organisms possess an inherent drive toward self-improvement. Numerous paleontological discoveries indeed point to real changes in organisms over time and The formation of more complex, better adapted, and more perfect forms. Today, the general Progressive development of Living matter is accepted by the majority of scientists as its intrinsic property. At the same time, it would be a major mistake to assume that the problems of progressive evolution have already been fully resolved.

METABOLISM/2.html">THE CONCEPT OF progress can be considered subjective because it is predominantly used with reference to humanity (representing an ongoing trend in Human Development characterized by the predominance of later societal forms over earlier ones according to specific criteria). Furthermore, depending on the approach, the exact same events can be viewed as either exclusively progressive or entirely regressive (one might recall historians' frequent reassessments of the events of the past century). Following V. Grant's perspective, we face two main questions: 1) can we transfer the concept of progress from human activity to evolutionary biology; 2) can this concept be shifted from a subjective to an objective level—that is, can we find objective Criteria for the presence of progressive development in organic evolution? Answering these questions affirmatively, following Huxley, Grant defines progressive evolution as gradual adaptations to new habitats that increasingly distance the respective organisms from the ancestral environments of their precursors.

According to some views, progress in living nature is the perfection and complexification of the Organization of life (both of organisms and their interactions) during evolution, aimed at better adaptation to continuously changing environmental conditions. Sometimes progress is understood even more narrowly—as an increase in the adaptability of organisms to their living conditions (adaptorphogenesis). In this context, It is worth recalling the relative nature of adaptation itself and the fundamental impossibility of "complete" adaptation, which is why progress cannot be equated with the adaptive capacity of organisms. For instance, it is hardly appropriate to consider stegocephalians as a group highly adapted to terrestrial living conditions, yet these animals can be regarded as a crucial milestone in the overall progressive development of vertebrates.

Quite often, progressive evolution is equated with morphophysiological progress, i.e., orogenesis (it should be recalled that this direction of phylogenesis can be accomplished not only through aromorphic transformations but also via general degeneration, as discussed in detail earlier). At the same time, it is impossible to separate progressive transformations from the regressive development of at least some structures, and this applies to almost all organisms.

To date, A large number of criteria have been proposed to define progressive evolution. One of the earliest among them is the complexification of the ORGANIZATION OF THE respective organisms. Indeed, with The Development of nature, we observe a substantial complexification of living beings. Unicellular organisms have a significantly simpler structure compared to any multicellular forms. With each transition to a new taxonomic group, a certain complexification of organization is also traceable. However, if we set aside high-level taxonomic generalizations, nature provides numerous Examples where relatively progressive development is accompanied by a certain simplification of at least some structures (simplification of limb structure in horses, reduction and stabilization of flower component numbers, phenomena of organ reduction that have lost their initial vital Functions, etc.). Therefore, structural complexity by no means always indicates the corresponding progressiveness of an Organism.

Scientists have developed the following criteria for progressive development: an increase in the energy level of life processes; growth in reproductive efficiency; improvement in the precision of external signal perception and The ability to respond to external influences; an enhanced ability to control the environment and reduce dependence on it; an increase in the degree of organismal differentiation; intensification of functions; a rise in the level of organismal Homeostasis; an increase in the volume of information perceived by the organism from the outside, along with improvements in Processing and utilizing it; an increase in the coefficient of performance; an increase in the degree of cephalization; and many others. According to O.I. Zotin and A.A. Zotin (1999), almost all of the mentioned criteria indicate an increase in both the energetic capabilities of organisms and their ability to acquire, store, and utilize information.

Without dwelling on all the listed criteria, we should note that almost all of them are relative and far from always capable of characterizing the general progressive development of organisms as a whole. For instance, regarding the increase in cephalization and informational capabilities of organisms, these criteria are nearly impossible to apply to plants or other objects that lack a Central Nervous system (in general, the formation of The Nervous System did not occur immediately after The Emergence of multicellularity, with Sponges being a case in point). However, it cannot be assumed that these organisms lack evolutionary progress altogether; paleontological data argue against such views. Criteria such as an increased level of homeostasis and the ability to control the environment while reducing dependence on it carry purely anthropocentric tendencies, designating only humans as the most progressive creature, which cannot be considered objective.

From these considerations, it becomes clear why no system of criteria for progress explains how both progressive and entirely primitive forms can coexist simultaneously. At the same time, paleontological data point to an extraordinarily large number of extinct forms which, by many criteria, can be considered significantly more progressive than contemporary relatively primitive organisms (dinosaurs compared to geckos; mammoths and echidnas, etc.).

According to the most pessimistic views—especially among scientists with physical approaches to studying biological processes—the dominant trend in the development of living nature is the simplification of organization, degradation, and degeneration, i.e., regressive evolution. Such concepts are based on the Laws of Thermodynamics, according to which the evolution of any thermodynamic system tends toward state equilibrium (approaching Symmetry, whereas life is inherently asymmetrical from the very beginning).

The Essence of such views on the "regressive evolution" of life on Earth boils down to the idea that in the distant geological past, when major taxa were forming, evolution proceeded extremely actively, after which a significant decline in the evolutionary plasticity of organisms occurred, along with a decrease in their vitality, loss of "vital energy," etc. Thus, by comparing the sizes of ecological niches, generation turnover rates, microevolutionary processes, and many other indicators of biological activity in prokaryotes versus higher animals and plants, one might conclude that evolution is accompanied by a regression in the physiological capabilities of organisms.

According to many evolutionists, regressive transformations, much like progressive ones, are an integral characteristic of the evolutionary process. At the same time, The most significant error made by proponents of regressive evolution is their attempt to present isolated phenomena as the primary and Morphology/3.html">MAIN DIRECTIONS OF organismal development.

Summarizing the Overview of the problems of progress, it should be noted that a universally accepted definition of this phenomenon has not yet been formulated.

The problem is further compounded by the fact that, to quote Engels, every progress in organic development is simultaneously a regression, as it fixes a one-sided development and excludes the possibility of development in many other directions.

The situation regarding the development of a theory of progress is even more complex. It is evident that the most important breakthroughs in this direction still lie ahead. At the same time, various researchers highlight specific aspects of the progressive transformations of the organic world, demonstrating the relativity of our understanding of progress and regression as a whole. To clarify at least some CHARACTERISTICS OF THE progressive development of organisms, it is proposed today to distinguish several types of progress, which we will discuss next.