Biology Reference
In-Depth Information
applied to systems to give them order, while at the same time pro-
claiming that these systems are spontaneously organised from the
elements composing them. This demonstrates that real organisation
phenomena are not self-organisation but hetero-organisation phe-
nomena. Holism and self-organisation are not valid, alternative,
theoretical contexts to replace genetic determinism.
Ontophylogenesis resolves the contradictions in genetic deter-
minism and holism because it fully acknowledges the non-specificity
of biological molecules and the intrinsically stochastic character
which that imposes on the living organism. It substitutes a histori-
cal explanation for the explanation involving levels of organisation.
In this concept, it is neither the molecular that determines the
macroscopic, nor the reverse. Ontogenesis is an extension of natural
selection in the internal environment of organisms. A living being is
the product of a history in which selective constraints and stochas-
tic molecular events have been integrated into a single process.
We have seen that, based on this conception, more accurate
models of cell differentiation and gene expression can be con-
structed, models which incorporate experimental facts and lead to
predictions that can be tested. Computer simulation also demon-
strates that this is a relevant general theoretical framework for
explaining the principal properties of embryogenesis. However, it is
obvious that this concept must not be considered to have produced
a perfect theory, and the conclusion of this topic therefore opens
up two main aspects that we can immediately see should be devel-
oped in the future.
The first consists of constructing a much wider research pro-
gramme, which will certainly be modified as the first experiments are
performed. We can nevertheless outline the strategic direction. The
variability of biological parameters is a general, undisputable phe-
nomenon that all experimental biologists acknowledge. However, this
variability is not recognised by itself as a biological parameter which
can have a causal role. In the action of cellular mechanisms, which
have always been considered as fundamentally deterministic, it is seen
as a margin of fluctuation. Present research programmes, influenced
by genetics and molecular biology, are seeking to analyse genetic
