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These are excerpts and elaborations from my book "The Nature of Consciousness"
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Autocatalysis 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, Waechtershauserspeculates 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 Calvinwas 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
Kauffmanalso 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 Kauffmanviews 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. Back to the beginning of the chapter "The Evolution of Life: Of Designers and Design" | Back to the index of all chapters |
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