Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
The Origin of Variation
The debate on natural selection is mirrored by an equivalent debate on variation. It is not clear how genetic mutations (mutations in the DNA of an animal) result in phenotypic change (variations in the “body” of an animal). The issue, ultimately, relates to the problem of how a limited number of genes and a limited number of gene mutations can give rise to the very sophisticated complexity of living organisms. It also relates to the fact that “change” to a phenotype would seem more likely to harm than benefit the organism. Genetic mutation must be somehow directed for the odds of producing non-lethal phenotypic variation to be reasonable. Randomness alone would be too dangerous. It appears that evolutionary change would just not be feasible without that guiding hand.
The US biologists Marc Kirschner and John Gerhart proposed 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.
The theory of facilitated variation still does not explain its own premise: how did facilitated variation arise in the first place among living organisms.
The Israeli biologist Merav Parter (“Facilitated Variation”, 2008) proposed that facilitated variation is a natural occurrence in environments that change in a systematic way, by maintaining the same set of subgoals although organized in different combinations. In other words, the microscopic evolution of core biological processes would recapitulate the macroscopic evolution of the environment.
Facilitated variation might help explain “mosaic” evolution, a concept introduced by the British biologist Gavin de Beer in 1954 (“Archaeopteryx and evolution”) when he noticed that different traits evolve at different rates. He viewed an organism as a mosaic whose pieces could evolve separately. This might indeed be a key feature of any evolving system: to consist of parts that are so loosely coupled that each can evolved separately from the others without causing a collapse of the system as a whole.
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