Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
Since the pioneering work conducted in the 1960s by the German physicist Manfred Eigen (“Self organization of matter and the evolution of biological macro molecules”, 1971), autocatalysis has been a prime candidate to explain how life could originate from random chemical reactions. Autocatalysis occurs when a substance A catalyzes the formation of a substance B that catalyzes the formation of a substance C that… eventually catalyzes the formation of A again. At the end of the loop there is still enough A to restart it. All the substances in this loop tend to grow, i.e. the loop as a whole tends to grow. Life could have originated precisely from such a loop, in which case the chances that the right combination of chemical reactions occurred at the right time is much higher.
An autocatalytic set is a group of proteins that reproduces itself.
The power of this hypothesis is that "autocatalytic cycles" exhibit properties usually associated with life: metabolism and reproduction. If two such cycles occur in the same "pond", they will compete for resources and natural selection will reward the "best" one.
The German patent lawyer Gunter Waechtershauser ("Before enzymes and templates: theory of surface metabolism", 1988) improved on that model by explaining how the first forms of life could have synthesized their own vital chemicals rather than absorbing them from the environment, i.e. how a metabolic cycle could have started. Unlike Miller, Waechtershauser speculates that prebiotic reactions occurred not in water but on the ground. At high temperatures, chemicals bound to a metallic surface are much more likely to mix and form the complex molecules which are needed for life. Particularly, iron sulfide (a very common mineral on the Earth) could have been a catalyst of chemical reactions that created the biochemistry of living cells. He proved that peptides (short protein chains) could be created out of a few given aminoacids. The next step in the chain would be the emergence of RNA, that he considers a predecessor to DNA. Waechtershauser's emphasis is on "autocatalysis" (in general, as a process that is fast enough for yielding dramatic consequences) and on the ability of minerals in particular to catalyze the right reactions. Life would be but the natural evolution of a primitive chemical cycle that originally arose on an iron-sulfur surface.
The US chemist Melvin Calvin was perhaps the first to suggest that "autocatalytic" processes can make life more likely by speeding up the manufacturing of the basic ingredients.
The US biologist Stuart Kauffman also advanced a theory of how life may have originated from autocatalysis. He refutes the theory that life started simple and became complex in favor of a scenario in which life started complex and whole due to a property of some complex chemical systems, the self-sustaining process of autocatalytic metabolism. When a system of simple chemicals reaches a certain level of complexity, it undergoes a phase transition: the molecules spontaneously combine in an autocatalytic chemical process to yield larger molecules of increasing complexity and catalytic capability. In other words, as the system gets more complex, the chances that it contains a component and its catalyzer increase rapidly. Even if the proteins are chosen randomly, when there are enough of them, there is a chance that some of them form an autocatalytic set. Self-replication arises out of a simple statistical fact. Life, according to Kauffman, is but a phase transition that occurs when the system becomes complex enough.
According to Kauffman, life is vastly more probable than traditionally assumed. And life began complex, not simple, with a metabolic web that was capable of capturing energy sources.
Self-organizing principles are inherent in our universe, and Kauffman views life as a direct consequence of self-organization. Therefore, both the origin of life and its subsequent evolution were inevitable.
The US scientist Michael Conrad ("The Fluctuon Model of Force, Life, and Computation", 1993) developed a unified model of Quantum Physics and General Relativity, the "fluctuon model", according to which Physics is inherently biased towards self-organizing processes. He argued that life-like features stem from Quantum Physics and General Relativity themselves, and that life is therefore a relatively trivial consequence of the evolution of the universe.
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