Biomedical Engineering Reference
In-Depth Information
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Are complex organisms better (more) adapted (adaptive)
than simple organisms? i.e., is biology a relational science
(not merely a complex system)- throwing away the physics
and keeping the organization; or as Robert Rosen noted
" throwing away the polypeptide and keeping the active
site " (19).
It is noteworthy that living systems are not known to be structurally stable
(e.g., during morphogenesis and evolution); they are not highly ordered, i.e., the
order is not great but it is special; they are not program-driven or state-variable
determined, i.e., they are execution-driven; they are not digital-computational,
and equally surprising is that they are not far removed informationally from 1/f
noise communication (6,14).
An intriguing example of a subsystem assimilation challenge arises when a
new organ (heart, kidney, liver, lung, tissue, cells) is transplanted to a recipient
host. The explanatory model of the newly emergent functional order attributable
to graft-host interaction may benefit by evoking organizing principles of coevo-
lution. The heart as an autonomous organ system is endowed with an adaptive
plasticity (genotypic/phenotypic memory) and capacity to assimilate ("fitness
capacity") within the host and in the process modify the environment, determin-
ing the fate of the body system as a whole. The principles by which emergent
properties and the functional order of a self-organizing system, such as the heart,
achieve homeodynamic stability provide a non-reductionist framework for un-
derstanding how biological systems adapt to the imposed internal and external
stresses (e.g., organ/tissue replacement). The newly emergent dynamics arising
after an organ (heart) transplantation may represent a more stable, versatile, and
adaptive bipartite whole. The law of requisite variety, originally conceived by
Ross Ashby (7), dictates that the variety in the control system must be equal to
or larger than the variety of the perturbations in the local (body) environment,
i.e., the larger the variety of actions available to a control system, the larger the
variety of perturbations it is able to compensate/regulate.
The integrative collective behavior of living organisms cannot be reconsti-
tuted using the traditional reductionist approach, i.e., a mere assembly of parts or
their subunits. The whole emanates/evolves relationally from the emergent in-
ternal requirements of the constitutive whole-part subsystem organization
(3,11). A case in point is the dynamic rhythm patterns that evolve after cardiac
transplantation. Over time, the generated patterns resulting from the reunifica-
tion that takes place within the milieu of the recipient are not specified in the
equations of motion (5,12). The behavior of living systems must be treated as a
special case in which the description and representation must be inferred directly
from the system in question, much like general complex systems. This, of
course, implies that no identifiable single mathematical theory of complex sys-
tems exists that begs for completely new scientific methodologies and experi-
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