Biomedical Engineering Reference
In-Depth Information
environment, promotes stability, robustness, and adaptation. Evolution seems to
favor the building design of hierarchical order. The apparent advantages of a
multilevel pyramid (see Figure 2), with simple systems at the bottom and more
complex ones at the top, are the interfaces and linkages that are created by the
intermediates. The nature of these subsystems is dualistic: they behave as inte-
grating wholes to their respective parts and as parts to their respective higher
level wholes. The hierarchically organized benefit of this arrangement is inher-
ent in this modularity, whereby the decomposition into subsidiary parts does not
ruin or unbalance the entirety of evolutionary organization. Herbert Simon (13)
showed mathematically that complex systems evolve from simple systems with
greater rapidity if stable intermediate forms exist than if they do not.
All in all, evolution keeps the conserved biological (sub)systems in check
and thus robust to uncertainty in the local environment and to failure of the
component wholes. It would seem that reductionism, in its current incarnation, is
not likely to concatenate the fractionated parts together so as to make the selec-
tively disintegrated living organism whole again.
4.3. Heterarchy (Def: The Other, the Alien + to Reign, to Govern)
Organizational features embodied by heterarchical systems and the topo-
logic character of nested closed circuits, which were introduced nearly half a
century ago by the neurophysiologist and cybernetician Warren McCulloch (9),
can be considered a superset of the ordinary hierarchical forms. The concept of
heterarchy captures the essence of networked dynamic structures, in which the
center of control (authority) is redirected to whichever point is most relevant and
useful to accomplish the purposive activities. This form of organizational diver-
sity is particularly prevalent in brain function and autonomic function.
Today the network of relationships linking the human race to itself
and to the rest of the biosphere is so complex that all aspects affect
all others to an extraordinary degree. Someone should be studying
the whole system, however crudely that has to be done, because no
gluing together of partial studies of a complex nonlinear system can
give a good idea of the behavior of the whole.
—Murray Gell-Mann
The disintegration of a multilevel system can come about as a result of dys-
regulation in the level of communication (downward/upward causation). One
can argue that the abnormal growth of individual cells (certain types of cancers)
might be the result of loss of optimal amounts of communication (excessive,
