Thermodynamic theory answers the questions: what is driving force
In this small article, it is reasonable to address
only certain general philosophical theses regarding the basic aspects of
thermodynamic theory of biological evolution and aging, as well as consider
selected examples of its successful application in therapeutic practice.
General Theory of Understanding the Universe
"Understanding the universe demands a method". This well-known thesis ascribed to R. Descartes must be deeply understood when one starts to create general theories intended to describe the universe.
Two general means for understanding are known, namely, inductive and deductive methods.
The inductive method is based on reasoning from facts to a certain hypothesis, i.e., a general statement (from the partial to the general).
The deductive method (from the general to the partial) relies on the use of sequential conclusions related by logical statements (successions).
Today, the inductive method is generally used in the study of complex systems, such as biological ones. However, living objects are so complex that it is almost impossible to expect any success in constructing general theories and models of the origin and development of life based on the inductive approach. The realization of this circumstance and concepts on the meaning of science (as considered by the classics of natural science) lead us to the conclusion that noticeable advances in understanding the phenomenon of life may be expected if deductive methods are primarily used. However, this requires us to reconsider the approaches we used to create the general physical theory and the model of bio-matter evolution.
It should be noted that the theory by Charles Darwin and A. Wallace is a general biological theory that mostly describes the evolution of the forms of living beings at the level of populations. This theory does not try to discover the driving forces of biological evolution, phylogenesis, and ontogenesis.
Thermodynamics and Kinetics
There are two general approaches (methods) for the describing natural phenomena: thermodynamic and kinetic.
The thermodynamic description of systems and phenomena is based on the concept of the equilibrium state. Thermodynamics answers the question: what direction does a process follow before equilibrium is attained? It does not operate with time (in explicit form) as a parameter, and does not consider the mechanisms of processes.
On the contrary, kinetics directly studies the rates and mechanisms of processes.
Until recently, scientists studying the phenomenon of the origin of life, life evolution and the aging of living beings relied only upon kinetic theories. The fact is that the use of the thermodynamic (thermostatic) method for describing life phenomenon was, in a way, banned. It was stated for many decades that, since living systems are open, it is fundamentally impossible to apply thermodynamic (thermostatic) methods to these systems.
The Physical Theory of Biological Evolution and Aging
About a quarter century ago, the author realized that consistent use of the deductive approach for the study of phenomena in the bio-world should result in a relatively strict theory of physical evolution.
For me, as well as for many other scientists, a model of such an approach is given by J. W. Gibbs, the founder of the strictest (that is, the most accurate) physical theory. The experience of many classic natural scientists, such as R. Clausius, J.W. Gibbs, Le Chatelier, N. N. Bogolyubov, L. I. Sedov and others, allowed success to be hoped for.
The objective was to create a phenomenological theory, certainly one expressed in mathematical language, based only on the general laws of nature. There was every reason to believe that such a theory would be sufficiently strict, since it "must" be consistent with that of J. W. Gibbs. It hence became evident that the classic thermodynamic theory by J. W. Gibbs would become the "guiding star" of the new theory.
There was a need to create a thermodynamic theory of biological evolution and aging of living organisms, which would not principally contradict Gibbs' theory.
The main difficulty in creating a physical theory of biological evolution and aging was that a postulate had to be introduced that would allow real closed (quasi-closed) thermodynamic systems in the bio-world to be distinguished. This might give us a chance to employ the full capacity of thermodynamic variation principles.
About 25 years ago, there was only intuitive hope for this. I dare state now that this law has been formulated: the law of temporal hierarchies. However, one had to look at the structure and evolution of the bio-world from a somewhat different viewpoint before this law could be revealed and understood.
The Model of the Bio-World Structure
The understanding of the nature and driving force behind biological evolution as a whole, both phylogenesis and ontogenesis, becomes much easier if the evolution of the composition and structure of a bio-object and its hierarchic subsystems is studied.
Structure of the bio-world. If matter is studied in terms of composition and structure, every explorer first notices the hierarchic structure of the bio-world. For instance, a population is a group of organisms, which, in turn, consist of cells. The cells consist of organelles and other complex supramolecular aggregates; in turn, these are constructed of macromolecules as well as low-molecular compounds. On this basis, one can derive the concept of a hierarchic thermodynamic system as one consisting of hierarchic subsystems (interrelated by way of structural or some other subordination, and transition from lower to higher levels) distinguishable in terms of their location in space and (or) the time period required to establish a' relaxation equilibrium in these systems. There is every reason to believe that any higher (j - th) hierarchic system appears due to self-assembly, i.e., thermodynamic self-organization of structures belonging to the lower (j-1 - th) hierarchy. It appears that the mean lifetime of the structural elements of any lower hierarchy in a bio-mass (bio-matter) is generally much shorter than the mean lifetime of structures of any higher hierarchy.
The law of temporal hierarchies. It can be assumed from basic considerations that a relationship exists between the thermodynamic stability of structures within hierarchies of the same or different types, and their lifetimes in natural biological systems. This relationship can only be understood intuitively.
However, observation of nature shows that the lifetimes of bio-molecules, supramolecular aggregates cells in many tissues of the majority of organisms, as well as organisms and populations, form a series of strong inequalities. For instance, the lifetimes of amino acid molecules in tissues (from the instant these molecules appear in the cell, until the instant they are involved in chemical transformations) are much shorter than those of protein macromolecules in the cells. In turn, the macromolecules exist in bio-tissue cells for only a short time, in comparison with the lifetimes of the cells. The cells (or there parts) generally live for a much shorter time than the organism itself lives, while the lifetimes of organisms are much shorter than those of the populations they form.
Clearly, the above regularity ensures the possibility of metabolism between different hierarchies in bio-systems. This regularity cannot be derived from any known principles. Hence it should be considered that the series written by the author
is a general law of nature. Here t – average lifetime of “free” molecules-metabolites (m), supramolecular structures (im), organells (organell), cells in the tissue (cel); organisms (org); populations (pop); societies (soc).
As a matter of fact, the series (1) is an expression of the regularity that hierarchic structures have essentially different lifetimes. However, these
structural types are not general for all bio-systems. For instance, it is possible that certain cells (nerve cells, heart muscle cells) are not renewed throughout the human life. These cells are, as if, not cells in the usual sense; in this case, should be removed from the series (1). A similar phenomenon is observed for the fruit fly: no cell in the fly adult body undergoes division. Likewise, the proteins of the animal eye lens are almost never renewed. In this case, the lifetimes of these macromolecules do not fit the series (1) either. The space hierarchy does not match the temporal hierarchy in the above examples. In such a case, the corresponding lifetimes of the structures are as though involved in the next temporal hierarchy.
It can be easily shown that the existence of series (1) allows one to distinguish a set of structures of a certain temporal hierarchy as a subsystem, and to consider this subsystem as a quasi-closed system. Such a system can certainly be studied using quasi-equilibrium hierarchic thermodynamic methods. For example, since the majority of cell types live for a much a shorter time than the organism, it can be considered that the medium of the organism (organ) remains virtually unchanged throughout the lifetime of the cell. This medium plays the role of a thermostat (in a broad meaning of the term) for the quasi-equilibrium, kinetically quasi-closed organism subsystem, i.e., cells.
The above law represented by series (1) can also be worded as follows: "Any thermodynamic living system of any temporal hierarchic level in a normal state has a thermostat, i.e., a surrounding medium characterized by only insignificant changes in the mean thermodynamic parameters."
This statement is consistent with the metabolism (the exchange of matter) phenomena in the higher hierarchic bio-matter structures. The lower hierarchic level structures are repeatedly reproduced within the environment of the higher hierarchic level structures during the lifetime of the latter. Thus, we have:
where - average lifetime of structures of lower hierarchical level, - average lifetime of structures of higher hierarchical level.
The existence of low (1-2) allows us to use quasi-closed thermodynamic models to investigate living systems.
It should be remembered that every species of living beings (like certain tissue types) has its own characteristic lifetime of elements belonging to different hierarchic structures. However, the law (1-2), sometimes referred to as Gladyshev's Law, is valid for all lower hierarchic systems involved in a higher hierarchy (e.g., supramolecular aggregate, cell, organism, population, and so forth). For example, this law is valid for bacteria whose life span is close to 20 minutes. It is valid for a moth who lives for one day, for a fly living for about one month, for a mouse living for about three years, for a dog, living about 20 years, for a human, living about 100 years, etc.
Thus, a series of the type (1) in many cases can be characterized by the geometric series where is the mean lifetime of temporal structures of the n-th hierarchies in a particular hierarchic series of structures; and b are constants for the particular series; n = 1. 2. 3..... n.
The second law of thermodynamics is one of the general laws of nature that defines direction and completeness (degree of transformation or extent of a process) of real thermodynamic processes.
The second law states that for a simple isolated system (a system with constant internal energy and volume, in which no work or only work of expansion is carried out), that spontaneous (irreversible) processes increase system entropy, S. In this case the entropy grows towards the maximum value. An ideal gas is an example of such system. It should be stressed that in a system exchanging heat and work with its surroundings processes are possible that are accompanied by a growth or a reduction in the entropy of the system.
For systems of other types, the second law has equivalent forms (in mathematical respects) involving other state functions. For example, the criterion of spontaneous processes occurring in simple closed systems at a constant temperature and pressure is given by the variation of the Gibbs function (the Gibbs free energy) of the simple system, G, which leans (decreases) towards the minimum value. The criterion of spontaneous processes in simple closed systems at a constant temperature and volume is given by the variation of the Helmholtz function of the simple system, F, which also leans towards the minimum value. It should be noted that closed complex thermodynamic systems, i.e. systems in which not only work of expansion but also other types of work are carried out, are studied using the Gibbs function (), Helmholtz function (), and others, the variation of which characterizes the evolutionary changes in these complex systems.
As noted above, the existence of the law of temporal hierarchies in the bio-world allows us to consider a certain hierarchy of an open bio-system (at virtually all hierarchic levels) as a thermodynamic system existing in a thermostat (a medium with constant parameters). Self-assembly processes (thermodynamic self-organization) are observed in such open systems. Over certain time periods, this system can be regarded as kinetically quasi-closed, tending to increase the thermodynamic stability of its superstructure, which appears due to the interaction (self-assembly) of its constituent elementary structures. In this case, the second law states that at constant temperature, pressure and other thermostat parameters (which fluctuate within relatively narrow limits of possible adaptation of the living structure), the specific Gibbs function of the formation of the system structure under consideration, (or ) leans (goes for) towards the minimum value.
It should be noted once again, that depending on the type of thermodynamic system under consideration, the second law in classic thermodynamics is formulated in terms of variation of different state functions. Clearly, the formulation of this general law of nature from the viewpoint of entropy variation corresponds only to a particular (and rather rare) case for real systems, and hence it is of quite limited value This is often forgotten by many authors, resulting in incredible confusion and serious misunderstanding.
Life and the Role of Solar Energy
The compounds that were thermodynamically stable under the conditions of the primordial earth were transformed into diverse products, i.e., energy-rich chemical compounds, upon exposure to solar and other types of energy; the same process occurs today. Subsequently, these products undergo spontaneous "dark reactions" to give various compounds in accordance with the laws of chemical thermodynamics. The selection of these compounds for building supramolecular structures of living organism tissues occurs in dynamic systems in accordance with the laws of supramolecular thermodynamics. It is now generally believed that the formation of these supramolecular structures occurs under nearly equilibrium conditions. As a matter of fact, these processes are first order phase transitions occurring in nearly equilibrium systems. Obviously, these transitions are observed in the "linear range" where the laws of classic thermodynamics (thermostatics) are applicable.
At present, solar energy is utilized on the earth by green plants and certain bacteria to form the aforementioned energy-rich organic compounds
(M. Calvin, Lord Porter). These processes, called photosynthesis, occur with participation of pigments, e.g., chlorophyll. It should be noted that photosynthesis involves light and dark stages.
During photosynthesis, electrons are transferred from the donors, such as H20 and H2S, to the acceptor – CO2. These transformations result in carbohydrates and oxygen (if H2O is the electron donor), or sulfur (if H2S is the electron donor). Other reactions that can be the basis of photosynthesis are also known.
It is believed that oxygen appeared in earth atmosphere some three billion years ago. Oxygen became available for food oxidation; this eventually produced the highly organized organisms and higher hierarchies of the bio-world.
The basic photosynthesis reaction is usually expressed as:
where n is a carbohydrate, e.g., sugar (or cellulose). The change in the standard Gibbs energy (Gibbs free energy) for this reaction is = 480 kJ/mole, the standard reaction enthalpy change is = 470 kJ/mole, and the standard reaction entropy change is = -30 J/(K. mole).
Thus, exposure to solar energy results in the transformation of thermodynamically stable compounds (CO2, H20, and others) to give energy-rich compounds, while the chemical component of the Gibbs function of the system increases (> 0). The scheme presented in Figure I (The Summery of Technologies, no. 2, p. 61, 2000) demonstrates this statement, which is a generally accepted fact. As noted above, the photosynthesis products undergo subsequent spontaneous "dark reactions" ( < 0) to give diverse compounds. The latter spontaneously form supramolecular (im) structures ( < 0), the most stable of which are accumulated in the tissues of living organisms. It will be shown below that the selection of these structures occurs in accordance with the laws of supramolecular thermodynamics in quasi-closed dynamic systems (both in thermodynamic and kinetic respects).
As follows from the scheme, the lower hierarchy structures subsequently undergo self-assembly to give higher hierarchy structures. This structure formation can be understood easily from the equilibrium (quasi-equilibrium) hierarchic thermodynamic viewpoint.
It is thus evident that, from the viewpoint of the external energy source, the sun is the primary energy source and the driving force of non-spontaneous processes of matter circulation on earth (although other energy sources exist as well, such as atmospheric discharges, volcanic activity, etc.).
From the viewpoint of "dark" spontaneous processes, the "thermodynamic forces" are the driving force of the self-assembly and evolution of bio-structures at all hierarchic levels. These thermodynamic forces manifest themselves in ontogenesis, in phylogenesis, and throughout the entire evolution of bio-matter (as well as inorganic components and structures) on earth.
The scheme in Figure I also demonstrates that, due to the action of solar energy, bio-systems are continuously "fed" by energy-rich compounds synthesized in non-spontaneous processes. From this viewpoint, bio-systems do not spontaneously "move away" from some "vague equilibrium", as is generally accepted, but rather exist in a stationary state of matter circulation. In this relative circulation, the thermodynamically unstable compounds are continuously generated upon exposure to an external energy source.
The second part of the circle – the relative matter circulation - manifests itself as the tendency of living systems to the corresponding equilibria. These equilibria can be characterized using the thermodynamic evolution potentials introduced by the author. The Gibbs chemical potential is a particular case of the evolution potential. Clearly, the Gibbs approach can be expanded for the self-assembly processes (thermodynamic self-organization) in all hierarchic structures of the bio-world.
Spontaneous degradation of bio-molecules results in the "recovery" of compounds that are thermodynamically stable (under earth conditions) into the matter exchange cycle.
The Roles of Genetics and Environment
The evolutionary changes in tissues and organisms, both in the ontogenesis and in phylogenesis, are determined by two common factors. Separation of these factors is possible due to the fact that they manifest themselves over significantly different time periods.
The first (genetic or hereditary) factor manifests itself in the natural selection and long-term adaptation of the human organism to the conditions of life. The genetic features are generally fixed over long time periods, during the lifetime of many hundreds and thousands of generations. The second factor is related to environmental conditions, which are determined by climate specifics, type of food, and the optimum level of physical exercise and so on. This factor manifests itself through the adaptation mechanisms, and the results are observed over short time periods, usually much shorter than human life.
It is generally agreed that the human life span and health are primarily a function of genetic factors, the role of which is estimated at about 60-65%. The contribution of the environment, first of all food, is believed to be 35-40%.
As yet, the genetics of a particular human or animal can only be affected to a limited extent. On the other hand, as follows from the thermodynamic theory of aging, it is now already possible to stretch healthy human life by 15-20 years on average by using special diets and drugs. These foods and drugs can be selected by determining a quantitative indicator specifically, GPG, the gerontologic value of foodstuffs and various substances. The determination of this indicator is based on measuring the specific Gibbs function of the formation of various supramolecular structures in products of biological origin. In these cases, the supramolecular thermodynamic methods play the key role in the development of practical recommendations on keeping a human being healthy and young.
Facts and Practical Recommendations
It has been shown recently that understanding of the evolution of the composition and structure of living beings can be based on the thermodynamic study of hierarchic structures of different levels. As noted above, this approach makes it possible to reveal the driving force of the evolution and aging of living beings within the scope of the general laws of nature mentioned above, without using concepts of dynamic self-organization and dissipating structures, as well as some supposedly still unknown, laws of nature.
The calculations made using the supramolecular thermodynamic equations (Gibbs-Helmholtz equations, correlation equations by the author) make it possible to estimate the physiological (biological) age of the organism's tissues, and to provide a number of practical recommendations. One can introduce a concept of the gerontologic (anti-aging) value of foodstuffs.
The gerontologic value of a food, cosmetic, other natural product or compound (in accordance with one of the author's patents) is the quality of the product (substance) expressed in GPG units (or points), which characterizes its ability to support the organism's youthfulness and health, to rejuvenate its tissue and to beneficially affect the duration and quality life. It is noteworthy that gerontologically pure water one of the most gerontologically valuable products.
Based on thermodynamic calculations, it is easy, to formulate the general recommendations regard anti-aging diets, and drugs that hinder aging. Such diets and drugs can favor prophylaxis and treatment including the diseases of middle age.
The following can be said about diets. Diets that include "evolutionary-youthful" products of plant and animal origin favor longevity and improve the quality of human life.
The thermodynamic theory of aging explains the real (but not so large as was considered before) phenomenon of long-lived mountain dwellers, known in the centuries-old experience of mankind. As noted above, this phenomenon is primarily related to two general factors. The first is the genetic factor; the second concerns environmental conditions, namely the character of the food.
From the viewpoint of the thermodynamic theory of aging, the products of mountains and cold areas are the symbol of youthfulness.
All conclusions of the thermodynamic theory of aging are in good qualitative agreement with the centuries-old experience of mankind, and in particular, with Chinese medicine, Chinese and Japanese dietology, and with other reliable facts.
It can be hoped that, at the onset of the 21st century, a thermodynamic theory should soon allow us, I believe, to "postpone" aging by 15-20 years on average, and benefit the preservation of youthfulness and health in people o any age. The latter fact is quite important from a social viewpoint, since improving the health of middle-aged people would prolong their period of activity, and thus mitigate the unfavorable consequences of the "population explosion" on earth.
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* G.G. Komissarov noted the possible importance of H2O2 in the photosynthesis process (Chem. Phys., 1995, v. 14, No. 11, pp. 20-28) (in Russian).