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The motive force of the evolution of living matter and the therm


HomepageINSTITUTE of Physico-Chemical Problems of EvolutionBiological Evolution and AgingThe motive force of the evolution of living matter and the thermodynamic theory of aging

Georgi P. Gladyshev

Materials for the Conferens "Synergetics, ..." Alma-Ata, Sept., 1998.

Life in the Universe originated and is evolving in accordance with the general laws of nature, specifically, the law of temporal hierarchies and the second law of thermodynamics.

I . THERMODYNAMICS AND THE EVOLUTION OF BIOLOGICAL SYSTEMS

Evolution. In its common sense biological evolution is considered an irreversible process of the historical variation of life with respect to the evolution time scale characterising the given object. So, Ch.Darwin and A.Wallace's theories and the modern synthetic theory of evolution emphasize the evolution of populations. These theories study the causes, mechanisms and general rules of the evolution of living organisms from the biological point of view. Ch.Darwin's theory forms the theoretical basis of all biology.

The development of modern darwinism is connected with the analysis of the data obtained by molecular biology. It is aimed at a more profound understanding of hereditary variability and at finding the ways to control living natural resources.

However, up to now the theory of biological evolution did not attempt to point out the physical essence of the evolutionary trend, although Ch.Darwin admitted that the principles of life are a part or a consequence of some general law determining the evolution of matter as a whole.

The author assumes that life is a particular manifestation of the general natural laws.

It becomes much easier to comprehend nature and the motive force of biological evolution generally, as well as phylogenesis and ontogenesis, if one examines the evolution of the composition and texture, the structure of a biological object and its hierarchic subsystems.

Texturethe structure of the biological world. Analyzing matter from the angle of its composition and texture, one is struck by the hierarchic organization of the biological world. Thus, a population is a sum total of organisms, which in turn consist of cells. Cells consist of organelles and other complex supramolecular formations, which themselves consist of macromolecules and low-molecular weight compounds. Hence the conception about a hierarchic thermodynamic system as a system consisting of hierarchic subsystems can be introduce. There is every reason to believe that any higher (j) hierarchic structure emerges as a result of self-assembly, thermodynamic self-organization of lower-hierarchy (j-1) structures. It turns out that the average life-span of the structures that constitute the elements of any lower hierarchy in the biomass is significantly shorter than the average life-span of any higher-hierarchy structures.

The law of temporal hierarchies. To exactly formulate the law of temporal hierarchies (Gladyshevs law), let us consider a biological system consisting of the given organisms biological tissue cells, the organisms themselves, and the population formed by these organisms (i.e., a fragment of the hierarchic sequence of biological structures). Identifying the average life-span of structures makes it possible to assert that the average life-span (t) of a cell (cel) in the organism is much less than the average life-span of the organism (org), which, in its turn, is much less than the life-span of the population (pop):

...<< t cel << t org << t pop <<... (1)

The law (1) can be laconically formulated as follows: structures of lower hierarchy (j) live (exist) in biosystems much shorter than structures of higher hierarchy (j+1).

The series (1), which can be extended to all the hierarchies of the biological world, in a sense, sets the rules for the formation of self-reproducing identical polyhierarchic structures. Each higher structural hierarchy creates the habitat (the thermostat, in a broad sense, that is, the habitat where at certain intervals of time a number of parameters are constant) for all lower-hierarchy structures. If time hierarchies did not exist, the substance in such a world would stay in the state of homogeneous-heterogeneous mixture, and there simply would be no phenomenon of life. The law of time hierarchies, which correlates with the energy and spatial hierarchies of biological structures, determines the existence of an exchange of chemical substances and the organisms other hierarchic structures in a living system. Fig.1 illustrates the law of time hierarchies.

Fig.1. Relation between the characteristic sizes (l) of structures belonging to different hierarchies and their life-spans (t) in the biomass.
The dependence is presented in the logarithmic scale. The scheme is based on the facts relating to Homo sapiens.

The second law of thermodynamics is one of the general laws of nature, which establishes the direction and the degree of completeness of real thermodynamic processes. With regard to a non-equilibrium simple isolated system, perfect gas (i.e., a system with constant the internal energy and volume in which no work is performed, or only the work of expansion is performed), the second law establishes that should some spontaneous (irreversible) processes occur, a certain state function, called the systems entropy, S, increases and tends towards maximum values.

For another type of system, the second law is formulated by mathematically equivalent definitions using other state functions. Thus, for simple closed systems when temperature and pressure are constant, the criterion of the spontaneity of processes is a change of the simple-system Gibbs function, G, which tends towards minimum. For simple closed systems when temperature and volume are constant, the criterion of the processes spontaneity is a change of the simple-system Helmholtz function, F, which also tends towards minimum.

As was pointed above, the operation of the law of temporel hierarchies in the biological world makes it possible to consider each structure hierarchy of a real open biological system as a thermodynamic system located in a thermostat (environment with constant parameters). In such an open system, self-assembly processes can be observed. At certain intervals of time, this system may be considered as a quasi-closed one, tending towards an increase of the thermodynamic stability of its suprastructure, which is formed as a result of the interaction (self-assemly) of the elementary structures comprising it. In this case, if the temperature, pressure and the some other parameters of the thermostat are constant, the second law determines the trend towards minimum of the specific value of the Gibbs function of the formation of the system in question, .

Let us note again that depending on the type of the identified thermodynamic system, the second law in classical thermodynamics is formulated in terms of the change of the various state functions. It is clear that formulating this law of nature from the stand of a change of entropy for real systems is only a particular case and as such, has limited significance. Many authors forget this, thus causing confusion and serious misunderstandings.

As has recently been shown, the evolution of the composition and texture of living organisms may be comprehended on the basis of thermodynamic study of different-level hierarchic structures. This makes it possible to identify the motive force of evolution within the framework of the above-mentioned general laws of nature without falling back on the ideas of dynamic self-organization (or just self-organization, using I. Prigogins terms) and dissipative structures or on some supposedly still unknown laws of nature.

It has been established that the chemical composition of living organisms (e.g., plants and animals) changes in ontogenesis, phylogenesis and at the lengthy stages of the evolution of biological matter. In the course of evolution, the biological systems (organelle, cell, biological matter of an organism, biomass of a population, etc.) are enriched with energy-capacious chemical substances that oust water from these systems. These substances are mostly organic compoundslipids (fats), proteins, polysaccharides, nucleic acids, etc. Thus, at the moment immediately following conception, a human fetus is at least 95-97% water, while in an old persons tissues, water is depleted, its content falling to only 60-65%.
Fig.2. Variation of the amount of water and fat in a developing human embryo (Widdowson E.M. Body Composition in Animals and Man, 1967). 1 - water in tissue; 2 - fat in tissue. mfat and mwater- the amount of fat and water (weight %); M - mass of embryo.

Changes in the composition of biological tissues in ontogenesis are the most pronounced in young plants and animals. Variations of composition in the process of intrauterine development of animals, for example, mammals, are typical. Fig. 2 presents the findings of a study of the changes in the water and fat content in a growing human embryo.

II. MACROTHERMODYNAMICS

In 1976-1977, the author first put forth the opinion that the motive thermodynamic force of the evolution of living systems should be looked for, above all, in the spontaneity of the processes of formation and directional change of supramolecular structures of the living objects biological tissues (biomass structures). After the ideas set forth in G.P.Gladyshev, J. Theor. Biology, v. 75, p. 452, 1978, had been developed, specified and substantiated, a non-controversial physical model of biological evolution and the aging of organisms was built.

Examining the process of evolution as a change in the chemical composition of the biomass, its variation is connection not only with the spontaneous directional change of the supramolecular composition and texture of the biomass but also with the spontaneous change in the composition and texture of higher hierarchic structures, such as cells, organisms, populations, communities, etc.

However, 20 years ago, there existed (and still exists) the opinion that from in terms of building physical models and conducting calculations, it is pointless to talk about intermolecular interactions in complex systems (e.g., biological tissue) when it is impossible to identify a system of independently existing molecules. This opinion rests on the assumption that inter-molecular interaction is confined to a sum total of the interactions of each atom of one molecule with each atom of another molecule with account of environmental interaction. It is impossible to theoretically record the interactions of all the atoms of a heterogeneous system even in terms of microvolumes because of the systems surprisingly inconceivable complexity. This is why building calculation-based spatial models of biosupramolecular structures is practically impossible.

The author of the works mentioned above circumvented all these difficulties using the method of phenomenological thermodynamics applied by him to heterogeneous macrosystems. This method does not imply building any molecular models. It rests on the assumption that to establish the reasons of the spontaneous origin of life and reveal the direction of the evolution of biosystems, both phylogenesis and ontogenesis, on chemical and supramolecular levels can be revealed regardless of the surprisingly inconceivable complexity of the structure of biological objects, because the laws of thermodynamics operate at each local volume of supramolecular structures and, in the final analysis, at any (scale of) macrovolume of the biomass. In other words, it is in fact implied that there is an opportunity to identify real biological systems when it is expedient to experimentally calculate the values of thermodynamic functions, e.g., Gibbs and Helmholtz functions related to the units of mass or volume of biological objects. Experimental studies show that this approach, proposed for the study of complex heterogeneous systems, is useful and has good prospects.

This approach has paved the way for a new branch of thermodynamics, which can be called macrothermodynamics. The part macro in this term is used to stress that his branch of science studies heterogeneous (polyhierarchic) macroobjects. In the case of supramolecular systems, this means that the object of the study are systems in which independently existing molecules cannot be identified, e.g., organelles, cells and biological tissues. The branch of thermodynamics studying such systems was called supramolecular thermodynamics; its current object of study is the structure and behavior of supramolecular systems at phenomenological level

It should be noted that the thermodynamics of any systems or processes describes the behaviour of systems only on the macroscopic level. From this viewpoint, the term macrothermodynamics does not possess any special physical sense.

The use of the macrothermodynamic approach when studying the spatial structures of different hierarchic levels of living matter (such as, for instance, molecular, supramolecular, cellar, populational, etc.) has paved the way for the foundations of hierarchic thermodynamics.

Hierarchic thermodynamics (macrothermodynamics, or structure thermodynamics) studies complex heterogeneous chemical and biological systems, first of all, open systems that exchange matter and energy with the environment. According to the approach of hierarchic thermodynamics, such a system should be represented as a set of subordinate subsystems related hierarchically by their positions in space (structural, or spatial hierarchy) and (or) in time (temporal hierarchy).

It turned out that the origin of the structures of the various hierarchies of the biological world can be studied within the framework of models of equilibrium thermodynamics (thermostatics), and that ideas of thermodynamic self-organization (self-assembly) can be introduced with profit.

Thermodynamic self-organisation (self-assembly) is spontaneous ordered joining of the structures of i-th hierarchy into structures of (i+1)-th hierarchy. The process of self-assembly (or partial evolution) is a weakly non-equilibrium process similar to phase transition. For instance, formation of supramolecular structures from molecules in a cell can be considered as a phase transition from over-cooled state. Thermodynamic self-organisation is observed in systems close to equilibrium.

Identifying the concept of thermodynamic self-organization was extremely important owing to the need to distinguish this type of self-organization from dynamic self-organization (or, to use Prigogins term, just self-organization)a process in the course of which the organization of a dynamic system whose state is far removed from equilibrium is shaped, reproduced and improved.

As was noted above, it was realized that the existence of different-hierarchy structures in the biological worlds (and, incidentally, in the real world at large) proves possible thanks to the operation of a general law of nature, the law of temporal hierarchies.

The conclusions of the phenomenological theory, which are in fact based on the principles of scaling, correlate, in some way or another, with observations and experimental data relating to both phylogenesis and ontogenesis. At present, the prognostic force of the theory manifests itself most strongly as it applies to ontogenesis. This has paved the way for such a field of research as the thermodynamics (thermostatics) of aging.

The last achievements of macrothermodynamics and also data about the variation of the chemical composition of living organisms in ontogenesis confirm the thermodynamic tendency of aging processes. According to the thermodynamic theory the specific value of the Gibbs function of the formation of supramolecular structures of the organism tends to a minimum. That tendency explains the variation of the supramolecular and chemical composition and the morphology of tissues during aging. The theory makes it possible to define the principles upon which proper diets and medications can be devised to slow down aging. Such diets and medications are also useful in preventative care and in the treatment of various pathologies and among them those attending old age. The principle of the stability of chemical substance of the supramolecular structures of tissues makes it possible to understand the causes of the practically unlimited evolution of the biological world from the perspective of the second law in its classical definition.

III. THERMODYNAMICS OF AGING. WHY CELLS, ORGANISMS AND POPULATION AGE

Studies in this field provide an answer to the question of why cells, organisms, population age.

According to the thermodynamic theory of evolution, the structures of all biological hierarchies come into being, age and die. This assertion is fully in accord with the known facts showing that all living objects (systems) die, although their life-spans may be widely different.

From the biological viewpoint, the most vivid manifestation of the theory of evolution is the fact of the aging of organisms and cells. As for the aging and death of organisms, these are generally known phenomena, although they have caused disputes among biologists due to the very long life-span of individual biological objects. The issue of the possible immortality of cells had been much discussed in our century, and was settled thanks to the works of Dr. L.Hayflick.

It was established that cells are not immortal: each new tissue cell ages and dies. Most cells of an organism have a much shorter life-span than the organism itself.

Most of the known theories of aging deal with the aging mechanisms and emphasize the kinetics (dynamics) of the processes. There is extensive scientific and popular science resources dealing with the subject.

Another group of theories deals with the kinetic-thermodynamic aspects of aging. Most theories in that group rely upon models that deal with the changes in the production of entropy as a result of aging. These theories derive from the work of I. Prigogin and co-workers. These theories essentially account for the rate of heat release of living organisms. In that case the heat effects describe the intensity of biochemical processes and indirectly relate to the structure of a biosystem.

Moreover, the changes of entropy in an open system are related not only to heat effects of the processes internal to the system but also to exchanges with the environment. As a result it is practically impossible to conduct any meaningful calculations.

It should also be noted that in many natural systems (including the biological systems), not only the work of expansion takes place. In view of this, the increase of entropy as a criterion of spontaneous unfolding of processes becomes meaningless in such cases.

Now few words about important and known facts which any aging theory should be able to explain.

For example, the changes in the amounts of water and fat in an evolving human embryo (Fig.2) and other similar facts can be explained from the point of view of hierarchical thermodynamics bearing in mind the connecting link between the two hierarchies: molecular (chemical) and supramolecular (intermolecular).

Figure 3 shows that the motive force behind ontogenesis is the tendency of the specific supramolecular component of the Gibbs function of biomass (biotissue) to a minimum.
Fig.3. Schematic plot depicting the variation of the specific chemical energy capacity of the biomass - A (, or ) and the thermodynamic stability of its supramolecular structures during the ontogenesis of living beings - B ().
>>

The growth of the chemical component of bio-mass, that is its energy capacity is secondary. According to supramolecular thermodynamics and the Second Law the bio-system tends to accumulate energy-intensive chemicals that oust water from the system.

Figure 3 is in good agreement with the calculation we have conducted and experimental data.

Separation of thermodynamic functions into components in keeping with the hierarchy of the structures of the real world makes good sense, because there are uni-directional series of life spans ( or relaxation times) of structures in different hierarchies.

Figure 1 illustrates that regularity which evidently is a general law of nature.

Let us go back now to the lower part of Figure 3 and consider the possibility of prolonging the life- span of an organism. Let us review a diagram given in Figure 4.
Fig.4.Schematic variation of the Gibbs function corresponding to the formation of the aggregated phase of supramolecular structures for the biotissue of an organ of the j-th organism () in the course of ontogenesis.

A transition for curve to curve thermodynamically amounts to rejuvenation, and transition from to , to aging.

Therefore the rejuvenation of a specific organism (organ, functional system or any local zone of biotissue) is possible (against a background of constant genetic characteristics of a given organism) only through the changes of the parameters of its habitat. The fluctuations of the parameters of the habitat (changes in the atmosphere, changes of the food type, changes in the intensity of physical fields, etc.) cause changes of (or ), which either rejuvenate or age the biotissues of the organism within the limits of the adaptive zone and manifest the thermodynamic force of the environment in the ontogenesis of the organism.

Fig.5 Diets, incorporating thermodynamically juvenile foods of vegetable and animal origins facilitate longevity and improve the quality of life.
The extent of evolutionary juvenility of a natural foodstuff is determined by its chemical composition and supramolecular structure, which in turn depend on its phylogenetic and ontogenetic age, and also on the habitat of the organism - the source of the foodstuff. The value of the specific Gibbs function of the formation of the supramolecular structure is an important quantitative measure of the gerontological value of a natural foodstuff.

One of the applied aspects of the thermodynamic theory of the evolution of living organisms related to the problems of gerontology, dietetics, nutrition and some other medical and biological disciplines can be defined in the following manner (fig.5):

Diets, incorporating thermodynamically juvenile foods of vegetable and animal origins facilitate longevity and improve the quality of life. The extent of evolutionary juvenility of a natural foodstuff is determined by its chemical composition and supramolecular structure, which in turn depend on its phylogenetic and ontogenetic age, and also on the habitat of the organism - the source of the foodstuff. The value of the specific Gibbs function of the formation of the supramolecular structure is an important quantitative measure of the gerontological value of a natural foodstuff.

Fig.6 If a patient's diet incorporates evolutionary undeveloped species of plants and animals and uses the biomass of juvenile species he or she has a chance to enrich his own biological tissues with juvenile chemical matter, a building material corresponding in its composition to a young organism. Another important consideration is the habitat of the organism whose biomass is used for the preparation of food. From that point of view foodstuffs that come from highlands or cold seas have a high rejuvenating value.

If a patients diet incorporates evolutionary undeveloped species of plants and animals and uses the biomass of juvenile species he stands a chance to enrich his own biological tissues with juvenile chemical matter, a building material corresponding in its composition to a young organism (fig.6). Another important consideration is the habitat of the organism whose biomass is used for the preparation of food. From that point of view foodstuffs that come from highlands or cold seas have a high rejuvenating value (fig.7).

Fig.7 Viewed from the perspective of the thermodynamic theory of aging commercial companies will be well-advised to produce food additives, vitamin complexes and drugs that contain all physiologically important ingredients of living tissues. The dosage of components should be such that their concentrations in the tissues of a patient were close to the concentrations of these substances in the tissues of a young organism. The introduction of such preparations would make it possible to rejuvenate not only individual tissues, but the entire organism.

Viewed from the perspective of the thermodynamic theory of aging commercial companies will be well-advised to produce food additives and vitamin complexes that contain all physiologically important ingredients of living tissues. The dosage of components should be such that their concentrations in the tissues of a patient were close to the concentrations of these substances in the tissues of a young organism. The introduction of such preparations would make it possible to rejuvenate not only individual tissues, but the entire organism.

Let take a look now at some facts that have come to the fore as a result of the extension of macrothermodynamic theory.

V. THE PRINCIPE OF STABILITY OF SUPRAMOLECULAR STRUCTURES OF BIOLOGICAL MASS

The biological systems that we have been discussing are apparently governed by the principle of stabilization of chemical substance (Gladyshev's principle). The gist of that principle can be generally stated as follows: during the formation of the more stable structures of a higher hierarchical level (j) i.e., supramolecular structure, nature spontaneously predominantly uses the least stable structures of a lower hierarchical level, i.e., molecular (j-1).

The schema (Fig.8) illustrates that principle.

Gases and Water- H2 , N2 , O2 , CO2 , H2O
Tmol.decay
30001000 K
High molecular stability
Tmelting
20273 K
Low supramolecular stability
Tissues - Fats (Lipids), Proteins, Proteids, Sugars, RNA, DNA
Tmol.decay
320 380 K
Low molecular stability
Tmelting
273 383 K
High supramolecular stability
Fig.8 For instance, the molecularly (chemically) stable substances such as H2 , N2 , O2 , CO2 , H2O have relatively low melting and boiling points that indicates the low thermodynamic stability of their condensed phases. On the other hand, such energy-intensive substances (with low molecular thermodynamic stability) as sugars, peptides, nucleic acids melt at relatively high temperatures and decompose during melting and boiling. The aggregated phases of these substances are highly stable!

For instance, the moleculary (chemically) stable substances such as H2 , N2 , O2, CO2 , H2O, have relatively low melting and boiling points which indicates the low thermodynamic stability of their condensed phases (Fig.8). On the other hand, such energy-intensive substances ( with low molecular thermodynamic stability) as sugars, peptides, nucleic acids melts at relatively high temperatures and decompose during melting and boiling. The aggregated phases of these substances are highly stable!

The principle defined here is in agreement with the experimental data and calculations done for the Gibbs - Helmholtz equation.

It is very important to bear in mind that the principle of the stability of chemical substance (and substance of other hierarchies) is a thermodynamic principle. According to it the tendency of biological system during evolution (ontogenesis and phylogenesis) to generate relatively highly stable structures of higher hierarchies lead to the selection of relatively less stable structures of lower hierarchies. That evolutionary tendency of the biological system rejuvenates the lower hierarchical structures and causes unbounded evolution of the biological world.

One must not forget that natural selection at work at higher hierarchical levels is a manifestation of an important mechanism that assures the interaction of biological systems with the environment and helps their survival. But those problems first of all are in the realm of kinetics !

The theory outlined offers an answer to questions about the origins of life in the Universe and the motive forces of evolution and aging. That answer is the thermodynamic force.

Additional experiments could refine the theoretical model and stimulate an effort to obtain additional proof that the second law can undoubtedly be applied in its classical definition to explain the origins of life on Earth or elsewhere in the Universe.

References

  1. Gladyshev G.P. On the Thermodynamics of Biological Evolution. J.Theor. Biology. V. 75. P. 425, 1978.
  2. Gladyshev G.P. Thermodynamics and Macrokinetics of Natural Hierarchical Processes. M.: Nauka Publ.,1988.288p.
  3. Gladyshev G.P. Thermodynamic Theory of the Evolution of Living Beings. N.Y.: Nova Sci. Publ. Inc. 1997. 140 p.
  4. Gladyshev G.P. Thermodynamics of Aging. AAAS Annual Meeting and Science Innovation Exhibition (150th Anniversary Celebration), Philadelphia, Pennsylvania, Track: Emerging Science: Transforming the Next Generation, February 12-17, 1998. P. A-30, S-26.
  5. Gladyshev G.P. Thermodynamics of Aging .Biology Bulletin, N 5, ISSN 1062-3590, 1998.
  6. Lepock J. Supramolecular Thermodynamics. AAAS Annual Meeting and Science Innovation Exhibition (150th Anniversary Celebration), Philadelphia, Pennsylvania, Track: Emerging Science: Transforming the Next Generation, February 12-17, 1998. P. A-30, S-26.
  7. Klatz R., Goldman R. Stopping the Clock. New Canaan, Connecticut: Keats Publ. Inc. 370 p. 1996.
  8. Hayflick L. How and Why We Age. Ballantine Books, N.Y. 377 p. 1996.

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