Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
The German chemist Manfred Eigen†was awarded the Nobel Prize in 1967 for discovering that very short pulses of energy could trigger extremely fast chemical reactions. In the following years, he started looking for how very fast reactions could be used to create and sustain life.
Indirectly, he ended up studying the behavior of† biochemical systems far from equilibrium.
Eventually, Eigen†came up with the concept of† an "hypercycle". A hypercycle is a cyclic reaction network, i.e. a cycle of cycles of cycles (of chemical reactions). Then he argued that life can be viewed as the product of a hierarchy of such hypercycles.
A catalyst is a substance that favors a chemical reaction. When enough energy is provided, some catalytic reactions tend to combine to form networks, and such networks may contain closed loops, called catalytic cycles.
If even more energy is pumped in, the system moves even farther from equilibrium, and then catalytic cycles tend to combine to form closed loops of a higher level, or hypercycles, in which the enzymes produced by a cycle act as catalysts for the next cycle in the loop. Each link of the loop is now a catalytic cycle itself.
Eigen†showed that hypercycles are capable of self-replication, which may therefore have been a property of nature even before the invention of living organisms.
Hypercycles are capable of evolution through more and more complex stages. Hypercycles compete for natural resources and are therefore subject to natural selection.
The hypercycle falls short of being a living system because it defines no "boundary": the boundary is the container where the chemical reaction is occurring. A living system, on the other hand, has a boundary that is part of the living system (e.g., the skin).
Catalysis is the phenomenon by which a chemical reaction is sped up: without catalysis, all processes that give rise to life would take a lot longer, and probably would not be fast enough for life to happen. Then Eigen†shows that they can be organized† into an autocatalytic cycle, i.e. a cycle that is capable of self-reproducing: this is the fundamental requirement of life. A set of autocatalytic cycles gets, in turn, organized into a catalytic hypercycle. This catalytic hypercycle represents the basic form of life.
Formally: "hypercycles" are a class of nonlinear reaction networks. They can originate spontaneously within the population of a species through natural selection and then evolve to higher complexity by allowing for the coherent evolution of a set of functionally coupled self-replicating entities. A hypercycle is based on nonlinear autocatalysis, which is a chain of reproduction cycles, which are linked by cyclic catalysis, i.e. by another autocatalysis. A hypercycle is a cycle of cycles of cycles.
Eigenís model explains the simultaneous unity (due to the use of a universal genetic code) and diversity (due to the "trial and error" approach of natural selection) in evolution. This dual process started even before life was created.† Evolution of species was preceded by an analogous stepwise process of molecular evolution.
Evolution itself turns out to be inevitable: given a set of self-reproducing entities that feed on a common and limited source of energetic/material supply, evolution will spontaneously appear. Evolution is a direct consequence of the dynamics of self-reproducing systems.
That said, not all systems are suitable for becoming successful biological systems. Systems can be classified in four groups according to their stability with respect to fluctuations: stable systems (the fluctuations are self-regulating), indifferent systems (the fluctuations have no effect), unstable systems (self-amplification of the fluctuations) and variable systems (which can be in any of the previous states).† Only the last type is suitable for generation of biological information because it can play all the best tactics: indifference towards a broad mutant spectrum, stability towards selective advantages and instability towards unfavorable configurations. In other words, it can take the most efficient stance in the face of both favorable and adverse situations.
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