Science in Christian Perspective

Letter to the Editor

Problems of Chemical Evolution Not Solved by Prigogine
Walter Bradley 
Department of Mechanical Engineering 
Texas A & M University
College Station, Texas 77843

From: JASA 31 (June 1979): 127-128.

I would like to respond briefly to Dr. Jerry D. Alberts' communication entitled "New Insights into Thermodynamics" (Journal ASA, September, 1979). Having carefully read Prigogine's and Nicolis' new book Self-Organization in Nonequilibrium Systems (1977) (which I highly recommend), 1 believe Albert has greatly exaggerated the degree to which Prigogine's work has resolved the thermodynamic difficulties in chemical evolution. Prigogine, Nicolis and Babloyantz (1972, 1977) in commenting on biological complexity have recently noted:

''All these features bring the scientist a wealth of new problems. In the first place one has systems that have evolved spontaneously to extremely organized and complex forms..."

Furthermore, Prigogine repeatedly has argued that one cannot simply dismiss the problems by some vague appeal to non-equilibrium thermodynamics as Albert and many others do. The mechanisms responsible for the emergence and maintenance of coherent states must be established.

Nicolis and Prigogine (1977) have shown that a chemical system whose kinetic description involves a set of nonlinear equations is inherently unstable. In such a system a small fluctuation from steady-state may continue to grow larger, causing the system to move further from equilibrium, with an associated increase in energy dissipation. Nicolis and Prigoginc suggest two models that would have the required nonlinearity, a highly improbable (by their own admission) trimolecular model and a series of chemical reactions which explicitly show autocatalytic activity. For the trimolecular model, if the relative reaction rates satisfy very specific criteria, the boundary conditions are tightly controlled and rapid removal of reaction products throughout the system occurs, one can show a spatial variation of concentration of two molecules that were initially homogeneous. This very low degree of spontaneous ordering in view of the number of constraints required on the system causes one to wonder whether a system capable of producing biologically significant complexity would not have so many constraints and conditions required that their simultaneous satisfaction would be a miracle in its own right.

While autocatalytic activity can and does give the required kinetic nonlinearity in some important chemical reactions in the metabolism of living systems, it remains so be demonstrated experimentally that these models have any real significance in the prebiotic condensation of protein and DNA. No significant autocatalytic activity has been noted in these systems. More importantly, however, these models in their current formulation predict at best higher yields in otherwise unfavorable chemical reactions without any mechanism to control the sequencing which is absolutely essential to function. Prigogine, Nicolis and Babloyantz have acknowledged the great gulf between their hypothetical models and prebiotically significant reactions by commenting at the end of an article in Physics Today, November, 1972,

"One is tempted to hope (emphasis added) that these aggregation phenomena will provide valuable indications of how higher organisms develop'' (a much more cautious statement than that attributed to them by Albert).

Prigogine's work has clearly opened the doors to a better understanding of irreversible processes in living systems and the role energy and mass flow play in sustaining such systems. His work does not, however, give any adequate answer to how such living systems came into existence.

That a seed can become a tree or an egg, a chicken is not surpris ing if sufficient mass and energy flow through a system with a mechanism for converting the energy into the required specific work. Living systems through DNA and enzymes contain such a mechanism. Apart from living systems, nature is not full of "processes that bring order from chaos." Our dismal failures in synthesizing either protein under prebiotie conditions or DNA under any conditions suggests that the required nonlinearity via autocatalytic activity is absent. Neither can one solve the problem by arguing by analogy to a system such as eunventiunuus heat conduction that does have the required instability. It is certainly significant that theory predicts and experiments (as well as daily experience) confirm the existence of convectiuness currents. This stands in sharp contrast to synthesis of DNA and protein where the autocatalytic activity required by theory remains at present unconfirmed experimentally and the synthesis of these molecules, unsuccessful.
I would urge Dr. Albert to read more completely Prigngine's work to avoid drawing exaggerated conclusions and then describing those who might disagree as being "unwary or uninformed."