International Encyclopedia of Systems and Cybernetics

The set of historically acquired conditions that guides further evolution within some defined limits.

C. WADDINGTON, who was a biologist, proposed this concept and commented: "The process starts there in a single valley, but this later branches into two or more, and these branches split up again and again, until they have formed a number of separate valleys corresponding to the separate parts of the adult animal" (1977, p.141).

"Valley" should be understood in the topological meaning of "basin".

St. BEER, in turn, writes: "The genetic process, with its random mutations, is nonetheless conditioned by the prior history of the species" (1968, p.367). This is also true for the development of any individual living system and for any human organization or artefact.

What is not yet quite clear is why and how this potential capacity for branching into a fully organized system becomes actualized.

However, the following quotation about St. KAUFFMAN's understanding of epigenesis (by W. Mc CULLOCH, 1974, p.14) throws some light upon this point: "Interpreting each state cycle - a stable mode of behavior of the model genetic net – as a distinct cell type, he modeled the epigenetic landscape as flow among the "cell types" induced by random minimal perturbations to a running system. He found that such systems "flow" down an epigenetic landscape to a subset of cell types, and remain trapped among them… Simulation proved him right in model genetic nets of anything up to 8.000 components, beyond which computer memory balks" (1967).

MARUYAMA's model of deviation-amplification processes clearly shows how the process closes on itself and how the system "becomes trapped".

Anyhow any evolution can be understood as a "funnel" open in the direction of the future: anything remains possible, but then only within the conditioning limits of the already stabilized forms of organization.

There is seemingly an organizational closure at the mega-evolution level.