Does Entropy Play a Role in Biology?

Evgenii Rudnyi
Presented in the Embryo Physics Course, April 3, 2013


I worked in chemical thermodynamics for more than 15 years and I know how the thermodynamic entropy is used to solve practical problems.  On the other hand, in biology the term “entropy” is often associated with information and evolution. The goal of the talk is to make a short introduction to thermodynamics in order to show what is the original meaning of the thermodynamic entropy and how it is employed by chemists to compute equilibrium composition. After that, I discuss the relationship between the thermodynamic entropy and information and show that there is no information as such in the thermodynamic entropy. Finally, I discuss non-equilibrium thermodynamics and if there could be a connection between the entropy and evolution.







3 responses to “Does Entropy Play a Role in Biology?”

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  1. Accumulation of errors (mutations) in the genome is often considered as increase of “entropy”, simitar to the 2nd law of thermodynamics. For example, John Oller considers entropy in any kind of communication (including genome) as degradation of true narrative representations (“The Antithesis of Entropy: Biosemiotic Communication…”, Entropy 2010, 12, 631-705). Dr. Oller is a well-known creationist, he opposed teaching evolutionary theory at schools in Louisiana and wrote anti-evolutionary papers. One-directional change is consistent with religious idea that everything originates from one source (god). Entropy is used in the same context by other religious writers (Corrington, R.S. 2004. A Semiotic Theory of Theology and Philosophy). I consider this as a worrying trend. In particular, this view implies the existence of a true genotype, whose distortion is ‘entropy’. Then, whose genotype is “true”? This may lead to racism. I think that thermodynamic models are not relevant for living systems (they are not closed, not stable, and autopoietic). Instead, I prefer to focus on functionality. In particular, genome changes should be evaluated not by the number of nucleotide substitutions but by the change in living functions and by success in survival and reproduction.

  2. My goal was to introduce the thermodynamic entropy. In my personal view, it is unrelated to the information entropy.

    The entropies you have mentioned, I guess, closer to the information entropy.

  3. Georgi says:

    Origin of life and its evolution are the result of action of laws of hierarchical thermodynamics.
    Thermodynamics investigates systems which can be characterized by state functions. The separation of biological systems into individual hierarchies of structures allows us to study the processes in them independently of the processes that take place in other hierarchical structures.

    Criterion of evolution
    The approval about the reduction of the entropy of living systems as a result of biological evolution is incorrect. The criterion of evolution of living system is the change (during evolution) of the specific free energy (Gibbs function, G) of this living system. The evolution of living system takes place against the background of flows of energy (e.g., light, energy of physical fields) from the environment. It increases its specific free energy. At the same time, the specific free energy of this living system is decreased as a result of spontaneous processes in this system.
    Thus, the total change in the specific free energy of a living system is composed of two parts: 1. The change of free energy due to the inflow of external energy (G1> 0) and 2. The change of free energy due to spontaneous transformations in the system (G2 < 0) . The evolving system constantly adapts to a changing environment. The principle of substance stability contributes to this adaptation.
    Thermodynamics of evolution obeys the generalized equation of Gibbs (that is the generalized equation of the first and second laws of thermodynamics)*. Biological evolution and the processes of origin of life are well described by the hierarchical thermodynamics, established on the firm foundation of theory of JW Gibbs. Our theory created without the notion on dissipative structures of I. Prigogine and negentropy of L. Boltzmann and E. Schrodinger.
    “Thermodynamics serves as a basis for optimal solutions of the tasks of physiology, which are solved by organisms in the characteristic process of life: evolution, development, homeostasis, and adaptation. It is stated that the quasi-equilibrium thermodynamics of quasi-closed complex systems serves as an impetus of evolution, functions, and activities of all levels of biological systems’ organization. This fact predetermines the use of Gibbs’ methods and leads to a hierarchical thermodynamics in all spheres of physiology. The interaction of structurally related levels and sub-levels of biological systems is determined by the thermodynamic principle of substance stability. Thus, life is accompanied by a thermodynamic optimization of physiological functions of biological systems. Living matter, while functioning and evolving, seeks the minimum of specific Gibbs free energy of structure formation at all levels. The spontaneous search of this minimum takes place with participation of not only spontaneous, but also non-spontaneous processes, initiated by the surrounding environment.”
    Works of the author:

    Georgi Gladyshev
    Professor of Physical Chemistry

    *) The generalized equation of Gibbs (See: )

    P.S. Lastly, it is important to take into account, from the viewpoint of hierarchical thermodynamics, that anti-aging diets and many drugs can be used for the prophylaxis and treatment of cardiovascular diseases, cancer, and for numerous other illnesses.