Biology Reference
In-Depth Information
The mechanisms activated in his theory are therefore deterministic
mechanisms with noise. This is particularly well illustrated by von
Foerster's example of the magnets from which he took his inspira-
tion. The laws of the interaction of magnets are deterministic.
Depending on their polarity, magnetised surfaces attract or repel
each other. Agitating the magnets (the noise) only serves to set off
a new dynamic which will end in another state of organisation. For
Atlan, similarly, in actual biological systems, genetic information is
still an essential notion and proteins are always bearers of informa-
tion arising from their three-dimensional structure (FTG pp. 25, 33).
Noise only intervenes through perturbing their effects and modify-
ing the way the networks they constitute function. Like other
self-organisation theorists, Atlan has never questioned stereospeci-
ficity and the deterministic functioning of genes, which ensues from
it. His theory is still situated therefore in the context of the princi-
ple of order from order, and as a result, his views conform to
conventional theories of embryogenesis. He believes that Turing's
reaction-diffusion mechanisms create the gradients of morphogenic
molecules that control genetic expression (FTG pp. 44-47).
5.3.6
Self-organisation according to Weiss
Renowned experimental biologists have also for a long time been
providing support for the idea of self-organisation based on their
own work, among them the embryologist Paul Weiss (1898-1989),
who played a prominent role. For Weiss, the organism is not con-
structed from the gene, but is produced from the multiplicity of
interactions between the various levels of organisation going in both
directions, from the organism to the gene and from the gene to the
organism (Weiss, 1973). Two forms of determinism may exist:
macro-determinism corresponding to descending causality (from the
organism towards the gene) and micro-determinism corresponding
to ascending causality (from the gene towards the organism).
Macro-determinism is said to predominate over micro-determinism
(SL pp. 10-13).
