Jeffrey S. Wicken

Evolution in thermodynamic perspective: An ecological approach

Recognition that biological systems are stabilized far from equilibrium by self-organizing, informed, autocatalytic cycles and structures that dissipate unusable energy and matter has led to recent attempts to reformulate evolutionary theory. We hold that such insights are consistent with the broad development of the Darwinian Tradition and with the concept of natural selection. Biological systems are selected that re not only more efficient than competitors but also enhance the integrity of the web of energetic relations in which they are embedded. But the expansion of the informational phase space, upon which selection acts, is also guaranteed by the properties of open informational-energetic systems. This provides a directionality and irreversibility to evolutionary processes that are not reflected in current theory.For this thermodynamically-based program to progress, we believe that biological information should not be treated in isolation from energy flows, and that the ecological perspective must be given descriptive and explanatory primacy. Levels of the ecological hierarchy are relational parts of ecological systems in which there are stable, informed patterns of energy flow and entropic dissipation. Isomorphies between developmental patterns and ecological succession are revealing because they suggest that much of the encoded metabolic information in biological systems is internalized ecological information. The geneological hierarchy, to the extent that its information content reflects internalized ecological information, can therefore be redescribed as an ecological hierarchy.This thermodynamic approach to evolution frees evolutionary theory from dependence on a crypto-Newtonian language more appropriate to closed equilibrial systems than to biological systems. It grounds biology non-reductively in physical law, and drives a conceptual wedge between functions of artifacts and functions of natural systems. This countenances legitimate use of teleology grounded in natural, teleomatic laws.

The generation of complexity in evolution: A thermodynamic and information-theoretical discussion

Abstract It is argued that the evolutionary tendency toward complexity derives from the Second Law of thermodynamics and the set of physicochemical constraints provided by the biosphere. Complexity-generating processes provide the means by which thermodynamic information resulting from solar energy influxes can be dissipated. In particular, reductions in energetic information promote the growth of molecular size, and reductions in configurational information promote aperiodicity in molecular sequences. Natural selection converts the sequence entropy generated in these processes into molecular information.

A thermodynamic theory of evolution

Abstract As a closed thermodynamic system subject to an essentially constant free energy gradient, the biosphere must evolve toward a stationary state of maximum structuring and minimum dissipation with respect to this applied gradient. Since biological evolution occurs opportunistically through chance and selection, rather than as a direct response to the free energy gradient, the conformance of this phase of evolution with thermodynamics requires that natural selection, and the particular adaptive strategies employed by species of organisms, be related to the principles of increasing structuring and decreasing dissipation. In this paper, some general features of this relationship are proposed.

Information transformations in molecular evolution.

Abstract The prebiotic evolution of chemical systems is characterized by their development of increasingly complex levels of molecular organization. This development is dependent upon the capacity of these systems to acquire and transform chemical information. The informational content of a chemical system can be divided into configurational, energetic, and thermal contributions. The thermal information is specifically related to the number of molecules in the system, and is therefore a function of molecular size or complexity. The molecular complexity of a chemical system can be increased through reactions in which reductions in configurational or energetic information are coupled to increases in thermal information, as limited by the second law of thermodynamics.

On quantifying hierarchical connections in ecology

Introduction Natural selection is not just an antecedental accumulator of ecological success. It also has predictive power in the sense that some strategies for surviving and leaving offspring work better than others in the ecological arena . Adaptive strategies involve the effective utilization of resources, which brings thermodynamic considerations to bear on selection . The idea that selection has a predictive basis in thermodynamics was first explicitly articulated by Lotka (1922), who argued that those organisms would tend to be selected that were most effective in channelling energy flows through themselves and, at the same time, in increasing total flow through their ecosystems . The importance of this conception is that it suggested that natural selection operated hierarchically-on individuals, populations and the higher-order flow patterns in which they participated . This theme has been elaborated in recent years by H . T. Odum (1971). Another general trend in developing ecosystems has been toward increased efficiencies, as measured by biomass/throughput ratios (Margalef, 1968) or specific entropy production . Specialization of flow patterns also increases with ecosystem maturation, as measured by reductions of parallel pathways for processing energy (Ulanowicz, 1980) . These trends in ecosystem development suggest systems level principles for their explanation . In a much referenced paper, E . P. Odum (1969) has advanced 24 empirical indices of ecosystem development . These indices can be divided into two general categories . One involves macroscopic trends (e.g . toward increased biomass and closure of mineral cycles); the other involves mesoscopic shifts in typical adaptive strategies at the level of populations (e .g . from r selection to K selection) . A coherent theory of selection must connect the two trends . Before indicating the grounds on which we are suggesting this connection be made, let us note that ecology is occasionally criticized as a discipline that settles for less than rigorous scientific explanations (Ghiselin, 1974; Peters, 1976) . Ghiselin argues that ecology excessively resorts to functional explanations for selection (i .e . what the

Evolutionary self-organization and entropic dissipation in biological and socioeconomic systems

This paper considers some of the thermodynamic principles that underlie, and conceptually connect, self-organizing phenomena in both the biological and socioeconomic realms. The general thesis is that all evolutionary and development processes can be understood as proceeding within certain ‘economies’, established by prevailing energy gradients and kinetic mechanisms for their utilization. Of particular concern will be the ingredients in the relationship between organization and entropic dissipation, the global trends these ingredients impose on evolutionary processes, and the manner in which information is generated through the competition of thermodynamic flow patterns.