Piero Scaruffi

These are excerpts and elaborations from my book "The Nature of Consciousness"

The Irreversibility of Life Not everybody agrees with Prigogine’s view of living systems as dissipative structures and with Schroedinger's view of life as "negentropic". A law known as “Dollo's law” states the irreversibility of biological evolution: evolution never repeats itself. Darwin's natural selection does not necessarily prescribe progress or regression, does not imply a direction of evolution in time, it only states an environmental constraint. Indirectly, Dollo's law does: it prescribes a trend towards more and more complex, and more and more ordered, living structures. Dollo's law expresses the visible fact that reproduction, ontogeny and phylogeny are biological organizations whose behavior is irreversible: both during growth and during evolution. Entropy of biological information constantly increases. We evolved from bacteria to humans, we grew from children to adults. The goal of the unified theory of evolution put forth in the 1980s by the Canadian biologist Daniel Brooks and the US ecologist Edward Wiley is to integrate this law with natural selection. Unlike Prigogine, Wiley and Brooks believe that biological systems are inherently different from dissipative structures. Biological systems, unlike physical systems, owe their order and organization to their genetic information, which is peculiar in that it is encoded and hereditary. Dissipation in biological systems is not limited to energy but also involves information, because of the genetic code, which is transmitted to subsequent generations. Organisms simply live and die, they don’t evolve. What evolves is the historic sequence of organisms, which depends on genetic code. The genetic code must therefore be placed at the center of any theory of evolution. Unlike most theories of information, that use information to denote the degree to which external forces create structure within a system, Brooks-Wiley's information resides within the system and is material, it has a physical interpretation. It resides in molecular structure as potential for specifying both homeostatic and ontogenetic processes (processes for, respectively, maintaining internal equilibrium and growing). As the organism absorbs energy from the environment, this potential is actualized and is "converted" into structure.  What they set out to prove (following Lotka's original intuition) is that evolution is a particular case of the second law of Thermodynamics, that Dollo's law is the biological manifestation of that second law. Biological order is simply a direct consequence of that law.  The creation of new species is made necessary by the second law and is a "sudden" phenomenon similar to phase changes in Physics.  Phylogenetic branching (the creation of new species) is an inevitable increase in informational entropy.  In this scenario, the interaction between species and the environment is not as important in molding evolution: natural selection mainly acts as a pruning factor. Over short time intervals, biological systems do behave like dissipative structures. But over longer time intervals, they behave like expanding phase space systems (as proved by Layzer). Their relevant phase space is genetic, an ever increasing genetic phase space. The Brooks-Wiley theory is Darwinian in nature, as it subscribes to the basic tenet that evolution is due to variation and selection, but, in addition, it also allows the possibility for evolution to occur without any environmental pressure.   Back to the beginning of the chapter "The Physics Of Life" | Back to the index of all chapters