Towards physical principles of biological evolution

Abstract

Biological systems reach organizational complexity that far exceeds the complexity of any known inanimate objects. Biological entities undoubtedly obey the laws of quantum physics and statistical mechanics. However, is modern physics sufficient to adequately describe, model and explain the evolution of biological complexity? Detailed parallels have been drawn between statistical thermodynamics and the population-genetic theory of biological evolution. Based on these parallels, we outline new perspectives on biological innovation and major transitions in evolution, and introduce a biological equivalent of thermodynamic potential that reflects the innovation propensity of an evolving population. Deep analogies have been suggested to also exist between the properties of biological entities and processes, and those of frustrated states in physics, such as glasses. Such systems are characterized by frustration whereby local state with minimal free energy conflict with the global minimum, resulting in "emergent phenomena". We extend such analogies by examining frustration-type phenomena, such as conflicts between different levels of selection, in biological evolution. These frustration effects appear to drive the evolution of biological complexity. We further address evolution in multidimensional fitness landscapes from the point of view of percolation theory and suggest that percolation at level above the critical threshold dictates the tree-like evolution of complex organisms. Taken together, these multiple connections between fundamental processes in physics and biology imply that construction of a meaningful physical theory of biological evolution might not be a futile effort. However, it is unrealistic to expect that such a theory can be created in one scoop; if it ever comes to being, this can only happen through integration of multiple physical models of evolutionary processes. Furthermore, the existing framework of theoretical physics is unlikely to suffice for adequate modeling of the biological level of complexity, and new developments within physics itself are likely to be required.2

Physical foundations of biological complexity

“…Here, we do not present the actual mathematical theory of frustration-driven evolution. It seems likely that physical and mathematical ideas and formalisms beyond those currently known are necessary to develop such a theory ( 141 ).…”

Holographic local quench and effective complexity

“…1 Introduction Complexity of a system, a state or a process is one of the most intuitively clear yet very elusive concepts in our perception of the reality [1]- [8]. It is unlikely that a unique, both universal and practically useful, definition of complexity might exist [2].…”

On the feasibility of saltational evolution

“…More generally, severe population bottlenecks that can be caused by environmental stress, and especially, catastrophic events, are known as times of evolutionary innovation when slightly or moderately deleterious mutations that are weeded out by purifying selection in larger populations can be fixed via genetic drift 12,[26][27][28] . The findings reported here show that the innovation potential 29 of population bottlenecks could be even higher than considered previously thanks to the possibility of abrupt major changes brought about my multi-mutational leaps. Such leaps can be one of the keys to the puzzle of the evolution of complex adaptations requiring multiple mutations that are adaptive all together whereas each is neutral or even slightly deleterious on its own 11,[30][31][32] .…”