Biology Reference
In-Depth Information
However, despite these notable exceptions, embryogenesis and phys-
iology have always been dominated by deterministic theories.
Our theory goes further. Not only do we suggest that the fun-
damental mechanism of ontogenesis is conceptually analogous to
natural selection because it combines molecular chance and cell
selection, but we also think that this mechanism is a true extension,
within cell populations which make up the internal environment of
living organisms (Bernard), of natural selection that produces the
evolution of species (Darwin).
This is what we shall discuss in this chapter, in which we shall
see how our theory resolves the contradiction in genetic determinism
by uniting ontogenesis and phylogenesis. We will start from the more
abstract principles and progress gradually towards the more specific
mechanisms explaining cell differentiation and gene expression.
6.1
Ontogenesis and phylogenesis are but one process
The non-specificity of molecules has an inevitable consequence
which must be taken into account in understanding ontogenesis: it
introduces randomness into interactions between proteins. The
great number of interactions possible from a set of molecules gives
rise to numerous potential structures, not just a single one as in self-
assembly or self-organisation. Each structure is an occurrence of a
set of possibilities which each has only a certain probability of being
produced. Consequently, the unique adult individual which results
from embryogenesis is not produced by a simple mechanism of
spontaneous assembly of molecules. Another mechanism must be
applied to the potential combinations of interactions between mol-
ecules to restrict them and only select one of the structures possi-
ble, which will relate to the unique adult individual (Kupiec, 1983,
1996, 1999). Living beings are the result of such a process in which
the very many interactions between non-specific molecules are sub-
jected to natural selection. It can be illustrated by a thought exper-
iment that is not intended to be realistic but explains this principle,
diagrammatically.
