Biology Reference
In-Depth Information
3.1. From self-organization to NTSM
We now want to address the relation between SO and complexity. Ordinary
forms of SO - those which can appear in relatively simple conditions, be they in
natural ones, like thunderstorms, or in artificial ones, like Belousov-Zhabotinsky
reactions - may show in certain cases significant degrees of robustness, but
they seem unable to achieve further increases in complexity. Let us take the
example of the so-called dissipative structures. A Dissipative Structure (DS) is
a phenomenon by which a set of nonlinear microscopic processes generates a
macroscopic-collective pattern in a situation of distance from thermodynamic
equilibrium
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maintained by the continuous action of a group of constraints, one
of which is the very pattern generated by the global dynamics. Now, although
in classical DSs (either physical or chemical) the emergent pattern may be
very complicated, its contribution to the maintenance of the process is always
'simple', in the sense that such global pattern cannot exert a variety of selective
local constraints on the microscopic dynamics. In Bénard's Convection Cells,
for example, the pattern only makes a molecule turn to the left or the right. Thus,
the generation of new complexity is only possible if the dissipative organization
of the system develops a remarkable degree of internal plasticity, so that certain
elements (and/or patterns) will be recruited to serve different roles in the system,
thus producing a new form of SM. But how?
The answer is a SM organization that produces local and selective constraints
(instead of only one or few global patterns). In other words, it has to be a
chemical organization, for physical systems in general do not have the capacity
to create a wide enough variety of dynamical constraints. On the contrary,
the chemical domain is based on relations among elements that generate new
elements, and these new elements may in turn give rise to different interactions,
which may produce new elements, and so on, bringing about a potentially
unlimited set. From the thermodynamic perspective, chemical systems are a
special kind of organization in which the construction of new molecular variety
through dissipative processes creates new conservative constraints (molecular
shapes), which in turn can modify the whole organization, and so on. A chemical
organization creates many local, selective constraints (new components) and its
global maintenance relies on many of them. Interestingly, some elements - called
catalysts - can modify the relations among elements, and therefore a chemical
system is potentially a domain where components can become rules and vice
versa.
In other words, the jump from physics to chemistry seems necessary for mate-
rial systems to reach a diverse enough spectrum of dynamic, constructive, and
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Unlike the case of self-assembling structures, which keep their order in thermodynamic equilibrium.
