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.

Punctuated equilibrium as the default mode of evolution of large populations on fitness landscapes dominated by saddle points in the weak-mutation limit

“…Under this concept, major evolutionary transitions, such as, for instance, emergence of multicellular organisms, involve emergence of new levels of selection (new Darwinian individuals), in this case, selection affecting ensembles of multiple cells rather than individual cells. These evolutionary transitions resemble phase transitions in physics (14)and 4 appear to occur rapidly, compared to the intervals of evolution within the same level of selection. The concept of evolutionary transitions can be generalized to apply to the emergence of any complex feature (15).…”

“…This notion implies that major evolutionary transitions occur through narrow population bottlenecks. As formalized in our previous work, the evolutionary 'innovation potential' is inversely proportional to Ne (14). There are, however, multiple indications that drift cannot be the only mode of evolutionary innovation and that novelty often arises in large populations thanks to their high mutational diversity (45)(46)(47)(48).…”

Emergent Quantumness in Neural Networks

“…Using the "quantization" of the free energy (31) and the optimal value for the Planck constant (26), the wave function (20) can written as As an example, consider a grand potential which can be expressed as a sum of a fixed time-independent term and a time-dependent term, i.e.…”

“…Speaking more generally on the biological evolution, one should mention Ref. [26] where the question of what kind of physics would be needed to describe evolution is discussed. The key point is a coexistence of two levels (genotype and phenotype) which is essentially entangled in a very unusual way from the point of view of conventional statistical mechanics.…”

“…The other point of a great interest is a very controversial, but tempting, idea of "emergent quantumness", that is, some quantum-like behavior of systems which are difficult to believe to be quantum per se [24]. Some authors use quantumness just as a metaphor to describe cultural phenomena [25] or genotype-phenotype duality in biological evolution [26], while others suggest the relevance of the true quantum phenomena in human brains [27,28]. On a more practical level, this line of thinking may be related to a much more pragmatic and solid concept of "quantum annealing" [29][30][31][32][33][34].…”