(Copyright © 2000 Piero Scaruffi | Legal restrictions - Termini d'uso )
Darwin's vision of natural selection as a creator of order is not sufficient
to explain all the spontaneous order exhibited by both the living and the
At every level of science the spontaneous emergence of order, or
self-organization of complex systems, is a common theme.
Living organisms happen to be mere accidents in this universal process. Natural selection and self-organization complement each other: they create complex systems poised at the edge between order and chaos, which are fit to evolve in a complex environment. The target of selection is a type of adaptive system at the edge between chaos and order. This is one of the three types of behaviors that are possible for large networks of elements (besides chaotic and ordered). This applies at all levels of organization, from living organisms to ecosystems.
Kauffman's mathematical model involves "fitness landscapes". A fitness landscape is a distribution of fitness values over the space of genotypes. Adaptive evolution can be represented as a local hill climbing search converging via fitter mutants toward some local or global optimum. Adaptive evolution occurs on rugged (multipeaked) fitness landscapes. The very structure of these landscapes implies that radiation and stasis are inherent features of adaptation. The Cambrian explosion and the Permian extinction may be the natural consequences of inherent properties of rugged landscapes.
Kauffman also advances his theory of how life may have originated. When a system of simple chemicals reaches a certain level of complexity, it undergoes a phase transition. The molecules spontaneously combine to yield larger molecules of increasing complexity and catalytic capability. Such autocatalytic chemical processes may have formed the basis for early life. Life began complex, with a metabolic web which was capable of capturing energy sources.
Arrays of interacting genes do not evolve randomly but converge toward a relatively small number of patterns, or "attractors". This ordering principle may have played a larger role than did natural selection in guiding the evolution of life.
Principles of self-organization also drive the genetic program which drives morphogenesis. A few behaviors at the cell level (e.g., differentiation) are actually unavoidable consequences of the properties of self-organization. They are not the product of selection, but rather of the properties of the systems that selection acts upon. Laws of form complement selection. In any event, the genetic program is not a sequence of instructions but rather a regulatory network that behaves, again, like a self-organizing system.
Kauffman is searching for the fundamental force that counteracts the universal drift towards disorder required by the second law of thermodynamics.