Biology Reference
In-Depth Information
bilayer. In each case the rules applying to the cells were strictly
identical, the only differences being in the quantitative values of the
parameters. As we can see, there is gradual movement from a
totally disordered situation to the organised bilayer. There is no
discontinuous break corresponding to the appearance of a new
property which might qualitatively change the system. The order
corresponding to the bilayer is not, by nature, different from the other
disordered cell configurations. In addition, experiments simulating
carcinogenesis (Fig. 26) show that order is not irreversible as would
have to be the case if it corresponded to the emergence of a new prop-
erty. It only needs a minor quantitative modification of a parameter
for it to be destroyed. In fact, we are dealing here with a counter-
example which shows to what point the concept of emergence is a
trap: the simulation illustrates how a property we had not predicted
and which seems to appear spontaneously in tissues can be perfectly
explained and reduced to the rules regulating how cells function.
6.4.7
Is the body a cell ecosystem?
The simulation experiments that we have performed demonstrate
that the Darwinian model has essential properties that one would
expect of a theory of cell differentiation, such as the ability to create
an organised structure, finite growth and reproducibility. Without
demonstrating
per se
that real organisms comply with this model,
this proves that it is a relevant general theoretical context for
analysing embryogenesis and interpreting experimental data.
Simulations can also be used to evaluate the theory of the body
as a self-organised cell ecosystem, as suggested by Jim Michaelson
(1993) then considered by Pierre Sonigo in collaboration with
Isabelle Stengers (Sonigo and Stengers, 2003). According to
Michaelson, the relationships between the different types of cells of
an organism can be compared to the instances of prey/predator
equilibrium that are established in a self-organised ecosystem. An
imbalance in these relationships is consequently the source of the
diseases which may affect it. This theory should not be confused
with ontophylogenesis. For Michaelson, embryogenesis is indeed
