Mark Kirschner and John Gerhart:
"The Plausibility of Life" (2005)

(Copyright © 2006 Piero Scaruffi | Legal restrictions - Termini d'uso )
The USA biologists Marc Kirschner and John Gerhart note that genetic variation might be random but phenotypic variation is not random: it has to fit the environment.

It is a well-known fact that minor differences in the genome can cause large differences in the phenotype. After all, the human genome is only six times larger than the genome of the bacterium E.coli. The same is true at a higher level of organization. People affected by microcephalus may have a brain one third the size of the normal brain but they exhibit 90% of normal faculties. There is no direct correlation between size and performance. This led them to believe that there must be processes at work that "facilitate" evolution towards meaningful forms.

They propose that variation is "facilitated" by "conserved core processes" that are not subject to change and are shared by all living organisms. These are the functions that allow the organism to survive phenotypic change. They are linked in a loose regulatory network, and they can reconfigure themselves to accommodate changes in non-core processes. For example, the same genes can yield a hand or an eye depending on which one and when and where gets "expressed". Those are factors that the core processes can alter by reconfiguring themselves. These core processes work as an insurance that random genetic mutations be channeled in the direction of phenotypic changes that are, if not useful, at least not harmful to the organism. Indirectly, they "facilitate" change. These processes reduce the requirement for simultaneity in the evolution of novelty.

They don't require any planning or "designer" because they are exploratory in nature (a "trial and error" kind of process). An assumption of this theory is that living organisms are not made of hard-wired parts but of weakly-connected parts. Loosely-coupled components allow to replace one with a new one without a complete collapse of function. They allow exploratory processes to work on them. Basically, an unstated postulate of this theory is that a system must be made of loosely-coupled components in order to be able to evolve, a general property that one should be able to apply to vastly different disciplines, from engineering to linguistics.

TM, ®, Copyright © 2006 Piero Scaruffi